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Hydrosphere protection
hydrosphere pollutant eco-protective
Water is one of the most important substances on Earth, on which the state of the animal and plant world depends. It is the most common inorganic component of living matter. In humans, water makes up 63% of body weight, in fungi - 80%, in jellyfish - 98%, and plants contain up to 95% of water. Seeds of plants, in which the water content does not exceed 10%, are forms of slow life. The same phenomenon - anhydrobiosis - is observed in some species of invertebrates, which, under adverse external conditions, can lose most of the water from their tissues and remain viable.
Water in nature is in a continuous cycle - it is constantly consumed and renewed.
The role of water
Water plays an essential role in both biological and climatic processes. Water is the universal solvent of chemicals. The significant role of water on the planet is due to its physical properties.
Water has a high heat capacity of 4.18 J/g K (the heat capacity of air is 1.009 J/g K). Under natural conditions, water slowly cools and slowly heats up, being the temperature regulator on Earth.
The density of water is maximum at 3.98°C and is 1.0 g/cm3. The density of water decreases with both increase and decrease in temperature. This anomaly determines the possibility of life in water bodies that freeze in winter. Since ice is lighter than water (its density is lower), it settles on the surface and protects the underlying layers of water from freezing. With a further decrease in temperature, the thickness of the ice layer increases, but the temperature of the water under the ice remains at the level of ~4°C, which allows aquatic organisms to survive.
Main sources of hydrosphere pollution
Water pollution is manifested in a change in physical and organoleptic properties, an increase in the content of sulfates, chlorides, nitrates, toxic heavy metals, a reduction in oxygen dissolved in water, the appearance of radioactive elements, pathogenic bacteria and other pollutants. It is estimated that more than 420 km3 of wastewater is dumped annually in the world.
The main sources of pollution of the hydrosphere are:
industrial waste water;
domestic waste water;
drainage water from irrigated lands;
agricultural fields and large livestock complexes;
All wastewater pollutants are divided into three groups:
biological pollutants: microorganisms - viruses, bacteria; plants - algae; yeast, molds;
chemical pollutants: the most common pollutants are oil and oil products, surfactants, pesticides, heavy metals, dioxins, phenols, ammonium and nitrite nitrogen, etc.;
physical pollutants: radioactive elements, suspended solids, sludge, sand, silt, heat, etc.
Types of water pollution
Chemical pollution can be organic (phenols, pesticides), inorganic (salts, acids, alkalis), toxic (mercury, arsenic, cadmium, lead), non-toxic. Eutrophication is a phenomenon associated with the entry into water bodies of a large number of biogenic elements (nitrogen and phosphorus compounds) in the form of fertilizers, detergents, and animal waste.
In Russia, the concentrations of pollutants exceed the MPC in many water bodies. When deposited on the bottom of water bodies, harmful substances are sorbed by rock particles, oxidized - reduced, precipitated. However, as a rule, complete self-cleaning does not occur.
Bacterial pollution is expressed in the appearance of pathogenic bacteria, viruses, protozoa, fungi, etc. in the water.
Physical pollution can be radioactive, mechanical, thermal.
The content of radioactive substances in water, even in small concentrations, is very dangerous. Radioactive elements get into surface water bodies when radioactive waste is dumped into them, waste is buried, etc. Radioactive elements enter groundwater as a result of their fallout with precipitation to the surface of the earth and subsequent seepage into the depths of the earth, or as a result of the interaction of groundwater with radioactive rocks.
Mechanical pollution is characterized by the ingress of various mechanical impurities (sludge, sand, silt, etc.) into the water, which can significantly worsen organoleptic characteristics.
Thermal pollution is associated with an increase in the temperature of natural waters as a result of their mixing with process waters. The temperature of wastewater from thermal power plants, nuclear power plants is higher than the temperature of surrounding water bodies by 10ºC. When the temperature rises, the gas and chemical composition in the waters changes, which leads to the multiplication of anaerobic bacteria, the release of toxic gases - H2S, CH4. There is a flowering of water, accelerated development of microflora and microfauna.
Environmental protection measures
To protect surface waters from pollution, the following environmental protection measures are envisaged.
The development of non-waste and waterless technologies, the introduction of water recycling systems - the creation of a closed cycle for the use of industrial and domestic wastewater, when wastewater is always in circulation, and their entry into surface water bodies is excluded.
Cleaning of drains.
Purification and disinfection of surface waters used for water supply and other purposes.
The main pollutant of surface waters is sewage, so the development and implementation of effective wastewater treatment methods is an urgent and environmentally important task.
Wastewater treatment methods
mechanical cleaning
Physico-chemical cleaning
Biological treatment
mechanical cleaning
Used to remove suspended solids (sand, clay particles, fibers, etc.) from wastewater. Mechanical cleaning is based on four processes:
straining,
upholding,
processing in the field of action of centrifugal forces,
filtration.
Straining is carried out in gratings and fiber traps. They are used to remove large and fibrous inclusions from wastewater (wastewater from the pulp and paper and textile industries). The width of the gaps is 10-20 mm.
Sedimentation is based on the free settling of impurities with a density c > c of water or the ascent of impurities with c< с воды. Процесс реализуется в песколовках, отстойниках, жироуловителях.
Sand traps are used to treat wastewater from metal and sand particles larger than 250 microns.
Settlers are used to treat wastewater from smaller suspended particles or fatty substances, oil products.
Wastewater treatment in the field of action of centrifugal forces is carried out in hydrocyclones and centrifuges. The mechanism of action is similar to that of gas cleaning cyclones.
Filtration is used to purify wastewater from fine impurities with a low concentration. Basically, two types of filters are used: granular - quartz sand, crushed slag, gravel, sulfo coal, etc. are used as filter material; fabric - filtering partitions are made of cotton materials, woolen, ceramic.
Physico- chemical methods cleaning
They are used to remove soluble impurities from wastewater, and in some cases - to remove suspended solids.
Flotation consists in enveloping impurity particles (oil products, fine suspensions) with small air bubbles supplied to waste water and raising them to the surface, where a foam layer is formed. In the case of electroflotation, gas bubbles are formed as a result of the electrolysis of water by passing an electric current (hydrogen, oxygen).
Coagulation is a physicochemical process of enlargement of the smallest colloidal and dispersed particles under the action of forces of molecular attraction. Aluminum sulfate and iron chloride are used as coagulants. If aluminum or iron ions necessary for coagulation are obtained by electrochemical means (electrolysis), then this process is called electrocoagulation.
The reagent method consists in the fact that wastewater treatment is carried out with chemicals - reagents, which, entering into a chemical reaction with dissolved toxic impurities, form non-toxic or insoluble precipitates. For example, calcium hydroxide and calcium chloride are used to purify fluorine-containing waters. As a result of a chemical reaction with toxic fluorine compounds, poorly soluble calcium fluoride CaF2 is formed, which can be removed from water by settling.
Neutralization - a kind of reagent method, designed to reduce the concentration of free H + or OH - ions to the established values, corresponding to pH = 6.5-8.5. Neutralization of acidic wastewater is carried out by adding soluble alkalis NaOH, Ca (OH) 2, Mg (OH) 2, and alkaline - by adding acids (hydrochloric, sulfuric).
Extraction is based on the redistribution of sewage impurities in a mixture of two mutually insoluble liquids (waste water and organic liquid). Used to isolate phenols, fatty acids, non-ferrous metals - copper, nickel, zinc, cadmium, etc.
Ion-exchange treatment consists in passing wastewater through ion-exchange resins that contain mobile and exchangeable ions - cations (often H+) or anions (often OH-). When waste water passes through resins, the mobile ions of the resin are replaced by ions of toxic impurities of the corresponding sign.
AT last years New effective wastewater treatment methods are being actively developed:
ozonation,
membrane purification processes (ultrafiltration, electrodialysis),
electric discharge methods of water treatment,
magnetic processing, etc.
Biological treatment
Biological wastewater treatment is based on the ability of microorganisms to use dissolved and colloidal organic and some inorganic compounds (H2S, NH3, nitrites, etc.) as a source of nutrition in their life processes. In this case, organic compounds are oxidized to water and carbon dioxide. Biological treatment is carried out in natural conditions (irrigation fields, filtration fields, biological ponds) or in special artificial structures - aerotanks, biofilters.
Aerotanks are open tanks through which sewage mixed with activated sludge slowly flows.
Biofilter - a structure filled with loading material (slag, crushed stone, expanded clay, gravel, etc.), on the surface of which a biological film of microorganisms develops.
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Surface waters are protected from clogging, pollution and depletion. To prevent clogging, measures are taken to prevent the ingress of various solid wastes and other objects into surface water bodies and rivers. The depletion of surface water is prevented by strictly controlling the minimum allowable runoff of water.
The most important and most difficult problem is the protection of surface waters from pollution, for which the following environmental protection measures are envisaged:
Development of non-waste and waterless technologies and water recycling systems;
Wastewater treatment (industrial, municipal, etc.);
Injection of sewage into deep aquifers;
Purification and disinfection of surface waters used for water supply and other purposes.
The main pollutant of surface waters is sewage, therefore, it is an environmentally very important task to develop and implement effective wastewater treatment methods. Most in an efficient way protection of surface waters from pollution by sewage are anhydrous and wasteless technologies. At the initial stage, it is created recycling water supply. Its system includes a number of treatment facilities and installations, which creates a closed cycle for the use of wastewater, which, with this method, is always in circulation and does not enter surface water bodies.
Due to the huge variety of composition of wastewater, there are various ways their purification: mechanical, physico-chemical, chemical, biological and thermal.
Treatment can be carried out by any one or combined methods, with the treatment of sludge (or excess biomass) and the disinfection of wastewater before discharging them into a reservoir.
At mechanical cleaning up to 90% of insoluble mechanical impurities are removed from industrial wastes by straining, settling and filtering: sand, clay particles, scale, etc., and up to 60% from domestic wastewater. To the main chemical methods refer neutralization, oxidation, ozonation and chlorination. At physical and chemical cleaning of wastewater removes fine suspended particles, mineral and organic substances. Coagulation, sorption, flotation, extraction and other methods are used. Biological the method is based on the ability of microorganisms to use for their nutrition many organic and inorganic compounds from wastewater (hydrogen sulfide, ammonia, nitrites, etc.). To thermal methods are used in the treatment of industrial wastewater containing mainly highly toxic organic components.
With all methods of wastewater treatment, from an environmental point of view, the treatment and disposal of the resulting sludge and sediments is very important (especially when treating toxic industrial wastewater). For this purpose, they are stored in special landfills, processed in biological facilities, processed with the help of plants (hyacinths, reeds, etc.) or burned in special furnaces.
One of the promising ways to reduce surface water pollution is download wastewater into deep aquifers through a system of absorption wells (underground disposal). With this method, there is no need for expensive treatment and disposal of wastewater and for the construction of treatment facilities.
Increasingly important in the protection of surface waters from pollution and clogging are agroforestry and hydrotechnical measures. FROM they can be used to prevent eutrophication of lakes, reservoirs and small rivers, the occurrence of erosion, landslides, bank collapse, and reduce polluted surface runoff.
Main activities for groundwater protection are to prevent the depletion of groundwater resources and protect them from pollution. As for surface waters, this is a big and complex problem that can be successfully solved only in close connection with the protection of the entire natural environment.
To combat the depletion of fresh drinking groundwater reserves, various measures are envisaged: regulation of the groundwater intake regime; rational placement of water intakes over the area; determination of the value of operational reserves as the limit of their rational use; introduction of a crane mode of operation of self-flowing artesian wells, etc.
Control measuresWith pollution of groundwater is divided into: 1) preventive and 2) special. The task of special measures is to localize or eliminate the source of pollution.
The most important measure to prevent pollution of groundwater in areas of water intakes is the arrangement around them sanitary protection zones (ZSO). These are territories around sources of centralized drinking water supply, created to exclude the possibility of groundwater pollution. They consist of three belts.
Special Events for the protection of groundwater from pollution are aimed at isolating sources of pollution from the rest of the aquifer. To eliminate local sources of pollution, long-term pumping of contaminated groundwater is carried out.
The fundamentals of water legislation prohibit the design, construction and commissioning of enterprises that are not provided with water treatment devices. Discharge of waste water is allowed only with the permission of the authorities that control water quality.
It provides for liability for violation of the rules for the use of waters (criminal, administrative, civil law and compensation for losses).
3. Protection of the lithosphere
Soil protection from progressive degradation and unreasonable losses - the most acute environmental problem in agriculture, which is still far from being solved. The main links in the ecological protection of soils include:
Soil protection from water and wind erosion;
Organization of crop rotation and tillage systems;
Land reclamation measures (combating waterlogging, soil salinization, etc.);
Reclamation of disturbed soil cover;
Protection of soils from pollution, and beneficial flora and fauna from destruction;
Prevention of unjustified withdrawal of land from agricultural circulation.
To combat soil erosion, a set of measures is needed: land management, agrotechnical, forest reclamation and hydraulic engineering. At the same time, it is taken into account that hydrotechnical measures stop the development of erosion in a certain area immediately after their installation, agrotechnical measures - after a few years, and forest reclamation - 10-20 years after their implementation.
For prevention of secondary soil salinization it is necessary to arrange drainage, regulate water supply, apply sprinkler irrigation, use drip and root irrigation, perform waterproofing of irrigation canals, etc.
For soil pollution prevention pesticides and other harmful substances, they use ecological methods of plant protection (biological, agrotechnical, etc.), increase the natural ability of soils to self-purify, do not use especially dangerous and persistent insecticidal preparations, etc.
When carrying out construction and other works related to mechanical disturbance of the soil cover, it is envisaged to remove, preserve and apply the fertile soil layer on the disturbed lands. The fertile layer is taken out and stored in special temporary dumps (piles). Reclamation (restoration) of disturbed lands is carried out sequentially, in stages.
Subsoil is subject to protection from depletion of mineral resources and pollution. It is also necessary to prevent the harmful impact of the subsoil on the environment during their development. According to the current legislation, in order to prevent environmental damage to subsoil, in particular, it is necessary:
Most fully extract from the bowels and rationally use the reserves of the main minerals and associated components;
To not allow harmful influence mining operations for the safety of mineral reserves;
Protect deposits from flooding, flooding, fires, etc.;
Prevent pollution of subsoil during underground storage of oil, gas and other substances, disposal of hazardous substances and production waste.
To prevent possible depletion of natural resources and preserve subsoil reserves, it is especially important to observe the principle the most complete extraction from the bowels of the main and associated minerals. This will reduce the scale of unjustified penetration into the earth's interior, which will significantly reduce waste from mining enterprises and improve the environmental situation.
One of the important problems associated with the protection and rational use of subsoil is integrated use of mineral raw materials, including the problem of waste disposal. The main directions of waste disposal and improvement of the environmental situation are their use as raw materials, in industry and construction, for backfilling goaf and for the production of fertilizers. Liquid waste after treatment is mainly used for water supply and irrigation, gaseous - for heating and gas supply.
4 . Protection of biotic communities
To preserve the abundance and population-species composition of biotic communities, a set of environmental measures is being implemented, which include:
Fighting forest fires;
Protection of plants from pests and diseases;
Field-protective afforestation;
Improving the efficiency of using forest resources;
Protection of individual plant species and plant communities
Major efforts in the fight with forest fires should be used for fire prevention. The cause of forest fires, causing irreparable environmental damage and huge economic losses, is, as a rule, the human factor. In this regard, explanatory work among the population is of paramount importance. People visiting the forest must know and strictly follow the rules of fire safety in forests. Failure to comply with these rules will result in administrative penalty, and intentional damage or arson of the forest are serious crimes.
Among the methods plant protection from diseases and pests. Give the best results preventive measures namely: supervision, quarantine service and various forestry activities.
The protection and exploitation of game animals, marine animals and commercial fish is carried out on the basis of the principles of scientific management of populations, conservation of species diversity and the gene pool. Under exploitation wild animals understand their use for obtaining valuable products and raw materials (meat, fur, fluff, antlers and other products) and their use for scientific, cultural, educational and other purposes.
Security and operation hunting animals should provide for reasonable prey, but not their extermination. If the removal of individual individuals from the population is biologically justified, then it contributes to the mobilization of the population of its ecological reserve, which is understood as the possibility of increasing productivity by increasing the offspring and its survival. If these principles are observed, fishing and hunting become an effective, active form of animal protection and contribute to the improvement of their populations.
The population-species approach to the protection and exploitation of game animals has taken root in our country since the early 1950s. and is currently dominant. Security and operation commercial fish and sea animals It is also based on the observance of the population-species principle.
Information about rare, endangered or endangered species of plants, animals and other organisms is contained in the Red Book. There are several versions of the Red Books: international, federal and republican (regional).
Every year, changes are made to the Red Books and new species that need special care. In 1996, a new edition of the International Red Book was published, which includes 5205 endangered animal species: 1096 species of mammals, 1107 birds, 253 reptiles, 124 amphibians, 734 fish, 1891 invertebrates (butterflies, beetles , bumblebees, etc.).
Land, water surface and airspace, which, due to their special environmental and other significance, are completely or partially withdrawn from economic use and for which a special protection regime has been established, are called specially protected natural areas (SPNA). Their main task is to preserve biological diversity in order to maintain the sustainability of natural ecosystems.
According to the Law on Protected Areas, adopted by the Duma on February 15, 1995, the following main categories of the natural reserve fund are distinguished: a) state nature reserves, including biospheric ones; b) national parks; c) natural parks; d) state nature reserves; e) monuments of nature; f) dendrological parks and botanical gardens
Introduction.
Water is one of the most amazing substances on our planet. We can see it in solid (snow, ice), liquid (rivers, seas) and gaseous (water vapor in the atmosphere) states. All wildlife cannot do without water, which is present in all metabolic processes. All substances absorbed by plants from the soil enter them only in a dissolved state. In general, water is an inert solvent, that is, a solvent that does not change under the influence of substances that it dissolves. It was in water that life on our planet once originated. Thanks to the oceans, thermoregulation takes place on our planet. Man cannot live without water. Finally, in the modern world, water is one of the most important factors determining the distribution of production forces, and very often the means of production. So, the importance of water and the hydrosphere - the water shell of the Earth, cannot be overestimated. Right now, when the growth rates of water consumption are enormous, when some countries are already experiencing an acute shortage of fresh water, the issue of reducing fresh water pollution is especially acute.
The basis of Russia's water resources is river runoff, which averages 4262 km3 in terms of water content of the year, of which 90% falls on the basins of the Arctic and Pacific oceans. to the basins of the Caspian and Seas of Azov, where more than 80% of the population of Russia lives and where its main industrial and agricultural potential is concentrated, less than 8% of the total annual volume of river flow falls.
The increase in water consumption by industry is associated not only with rapid growth the latter, but also with an increase in the water intensity of production, that is, an increase in water consumption per unit of production. So, for the production of 1 ton of cotton fabric, factories spend about 250 m3 of water, and for the production of 1 ton of synthetic fiber - 2590 - 5000 m3. A lot of water is required by the chemical industry and non-ferrous metallurgy: 1000 m3 of water is spent on the production of 1 ton of ammonia, 2000 m3 of synthetic rubber, and 4000 m3 of nickel. For comparison: 180 - 200 m3 of water is spent on smelting 1 ton of pig iron.
The use of water for economic purposes is one of the links in the water cycle in nature. But the anthropogenic link of the cycle differs from the natural one in that in the process of evaporation, only a small part of the water used by man returns to the desalinated atmosphere. The other part (about 90%) is discharged into rivers and reservoirs in the form of wastewater contaminated with industrial waste.
Of great importance is the satisfaction of the needs of the population in drinking water in their places of residence through centralized (priority) or non-centralized systems of drinking water supply. The sources of centralized water supply are surface waters, the share of which in the total volume of water intake is 68%, and groundwaters - 32%. In rural areas, the use of structures and devices of decentralized domestic and drinking water supply systems for drinking purposes prevails. Water from wells, springs and other sources of decentralized water supply is not protected from pollution and therefore poses a high epidemiological hazard.
Almost all surface water sources have been exposed to harmful anthropogenic pollution in recent years, especially such rivers as the Volga, Don, Northern Dvina, Ural, Ufa, Tobol, Tom, as well as other rivers of Siberia and the Far East. 70% of surface waters and 30% of underground waters have lost their drinking value and moved into the categories of pollution - "conditionally clean" and "dirty". Nearly 70% of the population Russian Federation uses water that does not comply with GOST "Drinking Water". A particularly difficult situation with pollution of surface water sources has developed in the Astrakhan, Kemerovo, Kaliningrad, Tomsk, Tyumen, Yaroslavl regions, and Primorsky Krai. There is an increase in pollution of groundwater used for water supply, including oil products, heavy metals, pesticides and other harmful substances that enter aquifers with wastewater.
Sources of water pollution. Sources of pollution are recognized as objects from which the discharge or other entry into water bodies of harmful substances is carried out, which worsens the quality of surface waters, limits their use, and also negatively affects the state of the bottom and coastal water bodies.
The protection of water bodies from pollution is carried out by regulating the activities of both stationary and other sources of pollution.
Federal executive authorities and executive authorities of the constituent entities of the Russian Federation protect water bodies from all types of pollution, including diffuse (pollution through the earth's surface and air).
Accidental pollution of water bodies occurs when hazardous substances are discharged into surface water bodies in a burst, which causes harm or creates a threat of harm to public health, the normal conduct of economic and other activities, the state of the natural environment, as well as biological diversity. Measures to prevent harmful effects on water bodies are determined by the water legislation of the Russian Federation.
On the territory of Russia, almost all water bodies are subject to anthropogenic influence. The quality of water in most of them does not meet regulatory requirements. Long-term observations of the dynamics of surface water quality have revealed a trend towards an increase in their pollution. The number of cases of high levels of water pollution (more than 10 MPC) and cases of extremely high pollution of water bodies (more than 100 MPC) is increasing.
The main sources of water pollution are enterprises of ferrous and non-ferrous metallurgy, chemical and petrochemical, pulp and paper, and light industries.
Ferrous metallurgy. The volume of wastewater discharged is about 12 billion m3, the discharge of polluted wastewater has reached 850 million m3. Enterprises in Magnitogorsk, Lipetsk, Yekaterinburg, Chelyabinsk, Cherepovets, Novokuznetsk do not provide standard wastewater treatment.
Non-ferrous metallurgy. The volume of polluted wastewater discharges exceeded 537.6 million m3. Wastewater is contaminated with minerals, fletoreagents (cyanises, xanthates), salts of heavy metals (copper, lead, zinc, nickel, mercury, and others), arsenic, chlorides, and other substances.
Woodworking and pulp and paper industry. The main source of wastewater generation in the industry is pulp production based on sulphate and sulphite methods of wood pulping and bleaching.
Oil refining industry. Enterprises of the industry discharged 543.9 million m3 of wastewater into surface water bodies. As a result, oil products, sulfates, chlorides, nitrogen compounds, phenols, salts of heavy metals, etc., entered the water bodies in significant quantities.
Chemical and petrochemical industry. During the year, 2467.9 million m3 of wastewater was discharged into natural water bodies, along with which oil products, suspended solids, total nitrogen, ammonium nitrogen, nitrates, chlorides, sulfates, total phosphorus, cyanides, thiocyanates, cadmium, cobalt, manganese, copper, nickel, mercury, lead, chromium, zinc, hydrogen sulfide, carbon disulfide, alcohols, benzene, formaldehyde, furfural, phenols, surfactants, carbamides, pesticides, semi-finished products.
Mechanical engineering. The discharge of wastewater from pickling and galvanizing shops of enterprises in this industry, for example, in 1993 amounted to 2.03 billion m3, including polluted - 0.95 billion m3, primarily with oil products, sulfates, chlorides, suspended solids, cyanides, nitrogen compounds, salts of iron, copper, zinc, nickel, chromium, molybdenum, phosphorus, cadmium.
Light industry. The main pollution of water bodies comes from textile production and the process of tanning leather. Wastewater from the textile industry contains suspended solids, sulfates, chlorides, phosphorus and nitrogen compounds, nitrates, synthetic surfactants, iron, copper, zinc, nickel, chromium, lead, fluorine and others. The leather industry releases water with a high content of nitrogen compounds, phenols, synthetic surfactants, fats and oils, chromium, aluminum, hydrogen sulfide, methanol and phenol into water bodies.
Domestic wastewater is water from kitchens, toilets, showers, baths, laundries, canteens, hospitals, household premises of industrial enterprises, etc. In domestic wastewater, organic matter is 58%, mineral substances - 42%.
Wastewater from ships is divided into three groups: fan, or fecal; household, including drains from galleys, showers, laundries; podslanovye, or oil-containing. Fan wastewater is characterized by high bacterial and organic pollution (chemical oxygen demand reaches 1.5–2 g/l). The volume of these waters is relatively small - their daily runoff, for example, on all ships of the Volga basin does not exceed 5-6 thousand m3. Podslane waters are formed in engine rooms and are characterized by a high content of oil products. In recent years, reservoirs have received many, many thousands of units of a small fleet (boats, boats with outboard motors). The small fleet has become a serious pollutant of water bodies.
Land water pollution. Pollutants can be conditionally divided into several groups. According to the physical state, insoluble, colloidal and dissolved impurities are distinguished. In addition, pollution is divided into mineral, organic, bacterial and biological.
Mineral pollution is usually represented by sand, clay particles, ore particles, slag, mineral salts, soluble acids, alkalis and others. Organic pollution is divided by origin into plant and animal. Vegetable organic pollution is caused by the remains of plants, fruits, vegetables and cereals, vegetable oil. Contaminants of animal origin are physiological secretions of people and animals, animal tissue residues, adhesive substances.
Bacterial and biological pollution is introduced mainly by domestic wastewater and effluents from some industrial enterprises (slaughterhouses, tanneries, primary wool processing factories, fur production, biofactories, microbiological industries).
The production and widespread use of synthetic surfactants (surfactants), especially in the composition of detergents, led to their entry with wastewater into many water bodies, including sources of domestic and drinking water supply. Along with surfactants, pesticides are widespread chemical pollution of water bodies, which enter water bodies with rain and melt water, washing them off from plants and soil, during air and ground processing of agricultural land and forests, and with effluents from enterprises producing them.
The Volga, the largest river in Europe and one of the largest in the world, is in a difficult ecological situation. More than 60 million people live in its basin, more than 30% of the industrial and agricultural products of our country are produced here. Due to inept, unreasonable, environmentally illiterate management, a departmental approach to the use of natural resources, to the development of industrial and agricultural production, the ecological situation in the Volga region has become catastrophic. Many times the river is blocked by deaf dams - blood clots. Half a century ago, flood waters passed the riverbed from source to mouth in 40 days, now this path takes 500 days. The extension of the water exchange terms threatens the river, choking from pollution, with irreversible consequences.
The volume of polluted wastewater discharged into the Volga basin is 37% of the total volume generated in Russia. The content of oil products in water is high, especially in the waters of Rybinsk and Yaroslavl. Water exhibits mutagenic activity, which was confirmed by three different bioassays. In the Saratov reservoir, the copper content ranges from 5-12 to 10-21 MPC. In the Astrakhan region, the content of phenols, oil products, copper and zinc compounds ranges from 5 to 12 MPC. The reduction in water exchange and the simultaneous increase in the volume of wastewater from industrial enterprises and the agro-industrial complex created a difficult hydrochemical situation. There was a threat of destruction of ecosystems in the Volga delta, and damage was done to human health.
A no less dangerous situation is observed in the Moscow River and the Oka.
In 100% of the fish caught, serious genetic anomalies were identified. Most mutants come across in the waters around Serpukhov and Voskresensk. The fish here suffer not only from cirrhosis of the liver and obesity, but also from eye diseases: The eyes crawl out of their sockets and then fall off altogether. According to preliminary data, the content of toxins in the body of abnormal roach, bream, and fish of other species exceeds the norm by tens and hundreds of times.
Since 1996, the Decree of the Government of the Russian Federation “On priority measures to improve the environmental situation on the Volga River and its tributaries, restore and prevent the degradation of natural complexes of the Volga basin” has been in force. In 1997, the implementation of the Volga Revival program was launched, developed by the Nizhny Novgorod Architectural Institute, designed for 15 years.
The problems of cleaning water bodies are not only in Russia. Many problems have accumulated in the United States and Canada in connection with the pollution of the Great Lakes. According to the US National Research Council and the Royal Society of Canada, they accumulate a huge amount of toxic chemicals. Scientists say that it takes 150 years to drink lake water to get the dose of toxic substances that residents of coastal areas receive by tasting lake trout only once. Of the ten fish caught in the state of Michigan and tested in the laboratory, nine were found to be contaminated with toxic substances to such an extent that they were not suitable for food. Birds and 16 species of carnivores living in the region have been found to have reproductive failures that have led to population declines. In the early 1980s, a US-Canadian commission registered 42 "areas of concern." Previous burials of toxic substances have led here to the concentration of poisonous bottom sediments. Cleaning these vast areas in terms of technology proved to be very difficult.
Pollution and self-purification of the seas and oceans. The following forms of anthropogenic impact represent a real danger to the ecological balance in the ocean: pollution of water areas; violation of the mechanism of reproduction of marine organisms; exclusion of coastal and water area for economic purposes.
Rivers carry industrial waste, sewage, and agricultural fertilizers into the ocean. The water spaces of the seas and oceans are the final receptacles for the vast majority of waste. Sea waters are polluted as a result of the burial of various wastes, the removal of sewage and garbage from ships, during the study of the bottom of the seas and oceans, and especially as a result of various accidents. For example, about 9 million tons of waste are dumped into the Pacific Ocean annually, and over 30 million tons into the waters of the Atlantic.
In March 1995, the bodies of 324 dolphins and 8 whales were found in the Gulf of California (USA). According to experts, one of the main causes of the tragedy is the pollution of the water basin with petrochemical waste and other toxic substances discharged by the industry of the United States and Mexico.
In cities near the coastline, pathogenic microflora is often found in sea water. Pollution fields are formed in the coastal waters of large industrial centers and estuaries, as well as in areas of intensive shipping and oil production.
The degree of water pollution in the ocean is constantly increasing. The ability of water to self-purify is sometimes insufficient to cope with the ever-increasing amount of waste being dumped. Under the influence of currents, pollution mixes and spreads very quickly, having a harmful effect on areas rich in animals and vegetation, causing serious damage to the state of marine ecosystems and the economy as a whole.
Oil and oil products.
Oil and oil products are among the most harmful chemical contaminants. More than 10 million tons of oil enter the ocean every year. Tankers pollute the surface, oil leakage during underwater drilling also contributes to pollution. Between 1973-1984 in the United States, the Institute for the Protection of environment and energy sector, up to 12,000 cases of water pollution by oil have been noted. Between 1970 and 1982, there were 169 major tanker accidents and 17,000 minor oil spills worldwide.
Public concern about oil pollution is due to the steady increase in economic losses in fishing, tourism and other areas of activity. Only 1 ton of oil can cover up to 12 km2 of the sea surface. And the oil film disrupts all physical and chemical processes: the temperature of the surface layer of water rises, gas exchange worsens, fish leave or die, but oil that has settled to the bottom harms all living things for a long time. The exchange of the ocean with the atmosphere is disrupted: energy, gases, heat and moisture, as a result, plankton, the main food of marine life, ceases to multiply. The richest community of the most diverse organisms develops in the upper 5-10 cm of the water column. It is called neuston. Here is a "nursery" of juveniles of many species of fish and invertebrates, which, growing up, inhabit the water column and the bottom of the seas and the ocean. Substances-pollutants, including oil and oil products, accumulate on the surface.
Heavy metals. French researchers found that the bottom of the Atlantic Ocean is contaminated with lead from land at a distance of up to 160 km from the coast and at a depth of up to 1610 m. A higher concentration of this metal in the upper layer of bottom sediments than in deeper layers indicates that this the result of human economic activity, and not a consequence of a long natural process.
The owners of the Tisso chemical plant in the city of Minamata on the island of Kyushu (Japan) have been dumping wastewater saturated with mercury into the ocean for many years. Coastal waters and fish were poisoned, which led to the death of local residents. Hundreds of people got severe psychoparalytic diseases. The victims of this ecological catastrophe, united in groups, repeatedly filed cases against Tissot, the government and local authorities. Minamata has become Japan's true "industrial Hiroshima", and the term "Minamata disease" is used in medicine to refer to the poisoning of people with industrial waste.
Household waste. Liquid and solid domestic waste enter the seas and oceans through rivers, directly from land, as well as from ships and barges. Some of these pollutants settle in the coastal zone, while others are dispersed in different directions under the influence of sea currents and wind. Household wastes are dangerous not only because they are carriers of human diseases (mainly of the intestinal group - typhoid fever, dysentery, cholera), but also because they contain a significant amount of oxygen-absorbing substances. Oxygen supports life in the sea, it is a necessary element in the process of decomposition of organic substances entering the aquatic environment. Municipal waste entering the water in very large quantities can significantly reduce the content of dissolved oxygen.
In recent decades, plastic products (synthetic films and containers, plastic nets, etc.) have become a special type of solid waste polluting the oceans. These materials are lighter than water, and therefore float on the surface for a long time, pollute sea coast. Plastic waste poses a serious danger to shipping: entangling the propellers of ships, clogging the pipelines of the cooling system of marine engines, they often cause shipwrecks. In addition, cases of the death of large marine mammals due to mechanical blockage of the lungs with pieces of synthetic packaging are known.
In the North Sea, there is a real threat of the death of flora and fauna due to pollution by sewage carried from the mainland by rivers. Coastal areas of the sea are very shallow; ebbs and flows in it are insignificant, which also does not contribute to the self-purification of the sea. In addition, on its shores there are countries with a high population density and highly developed industry. The environmental situation is aggravated by the recent development of oil production.
The mismanagement, predatory attitude towards the riches of the World Ocean leads to a violation of the natural balance, the death of oceanic flora and fauna in some areas, and the poisoning of people with contaminated products of the sea.
radioactive contamination. The burial of liquid and solid radioactive waste in the sea in the 1950s and 1960s was carried out by many countries with a nuclear fleet. For Russia, this problem is becoming more and more acute both in terms of compliance with international radiation obligations and in connection with the need to ensure the country's environmental safety. It was established that radioactive waste burials were carried out in five areas of the Barents Sea, not far from the landfill on Novaya Zemlya, in ten areas of the Sea of Okhotsk, the Sea of Japan and in the open part of the Pacific Ocean. Great Britain flooded radioactive waste in the Irish Sea, and France - in the North Sea, from where pollution fell into the Barents Sea.
There is practically no control over the radiation situation directly in the disposal areas. It is very difficult to determine the state of the protective barriers of buried waste, the rate and extent of the release of radionuclides. According to rough estimates of experts, the activity of buried waste is quite high.
Issues related to the disposal of nuclear submarines, the management of radioactive waste and spent nuclear fuel at the facilities of the Russian Navy, and the activities of the nuclear icebreaker fleet remain relevant today. On the Kola Peninsula, it is planned to build dry docks, storage facilities for radioactive waste, and berths for decommissioned submarines.
By the beginning of 1995, 121 nuclear submarines (NS) had been decommissioned in Russia, and 42 nuclear submarines had unloaded their cores. Temporary storage facilities are being built for decommissioned nuclear submarines. 8 nuclear submarines were dismantled with the reactor compartment cut out, 9 nuclear submarines were prepared for long-term storage afloat, 13 nuclear submarines are in the process of dismantling and preparation for long-term storage at shipyards and naval bases. 91 decommissioned submarines are kept in places of permanent deployment in unsatisfactory technical condition: their average service life is 32-35 years, up to 40% of them have not been under repair for more than ten years, it is extremely difficult to keep them afloat.
Self-purification of the seas and oceans. Self-purification of seas and oceans is a complex process in which pollution components are destroyed and included in the general circulation of substances. The ability of the sea to process hydrocarbons and other types of pollution is not unlimited. At present, many water areas have already lost the ability to self-purify. Oil, accumulated in large quantities in bottom sediments, turned some bays and bays into practically dead zones.
There is a direct relationship between the number of oil-oxidizing bacteria and the intensity of oil pollution of sea water. Largest number microorganisms were isolated in areas of oil pollution, while the number of bacteria growing on oil reaches 106-107 per 1 liter of sea water. Along with the number of microorganisms, their species diversity. This, apparently, can be explained by the great complexity of the chemical composition of oil, the various components of which can be consumed only by certain types of microorganisms. Oil-oxidizing microorganisms can be considered as indicators of oil pollution of water.
Marine organisms that are involved in self-purification processes include molluscs. There are two groups of mollusks. The first includes mussels, oysters, scallops and some others. They are characterized by a double shell. Usually, the shell valves are slightly ajar, and it is clearly visible how two tubes - siphons - stick out from under the rainbow mantle. Through one siphon, sea water is sucked in with all particles suspended in it, which are deposited in a special apparatus of the mollusk, and through the other, purified sea water is returned to the sea. All edible particles are absorbed, and undigested large lumps are thrown out. A large mussel mollusk can pass through itself up to 70 liters of water per day and thus purify it from possible mechanical impurities and some organic compounds. Like mussels, other marine animals also feed - bryozoans, sponges, ascidians.
In mollusks of the second group, the shell is either twisted, oval-conical in shape (rapana, littorina), or resembles a cap (sea saucer). Crawling over stones, piles, piers, plants, the bottoms of ships, they clean the huge overgrown surfaces every day.
A truly record holder is the cardium mollusk, which is part of the fauna of the Caspian Sea. Despite its small size (about 2.5 cm), in the process of feeding, it manages to filter up to 15 liters of water per day. At the same time, the oil components dissolved in it, as substances unsuitable for food, are enveloped in mucus and thrown to the bottom in this “packaging”.
Scientists are striving to study the activity of marine organisms, including algae, in order to find new effective ways to combat pollution of water bodies, especially the fish-rich Caspian.
Hydraulic structures. The concept of "hydraulic structures" includes: dams, buildings of hydroelectric power plants, water collection, drainage and water outlet structures, tunnels, canals, pumping stations, shipping locks, ship lifts, structures designed to protect against floods and destruction of the banks of reservoirs, banks and bottom of rivers, dams , enclosing liquid waste storage facilities of industrial and agricultural organizations, as well as other devices and structures designed to use water resources and prevent the harmful effects of water and liquid waste.
Depreciation and aging of the fixed assets of the water sector, the liquidation of a number of governing bodies, the lack of proper supervision of safe operation make it more and more possible to break through the dams of reservoirs and wastewater reservoirs, which can lead to catastrophic consequences and threaten the natural basis of human life. The environmental threat from hydroelectric facilities is manifested through:
· changes in the temperature and ice regime of rivers, which cannot but affect wildlife;
· Flooding of hundreds of millions of hectares due to violation of land use rules and destruction of underground utilities, flooding of buildings and other engineering facilities (huge funds will be required for artificial dewatering);
· erosion of the banks of reservoirs and, consequently, the reduction of land;
· Deterioration of environmental management conditions in the lower banks of the reservoirs, reduction of fish and other types of economy;
· Deterioration of the quality of natural waters in reservoirs and additional costs for water treatment in the domestic and drinking water supply system;
· death of flora and fauna from volley (emergency and hidden) discharges of industrial waste from storage tanks;
· ongoing construction of small hydraulic structures (dams, dams, road embankments, surface and underwater crossings, etc.) throughout the country without sufficient engineering justification.
These negative phenomena are most pronounced in the basins of the Volga, Don, Northern Dvina, Belaya, Tom, Tobol, and Tura.
The Federal Law “On the Safety of Hydraulic Structures” regulates relations that arise in the course of carrying out activities to ensure safety in the design, construction, commissioning, restoration, conservation and liquidation of hydraulic structures; establishes the responsibilities of the authorities state power, owners of hydraulic structures, and operating organizations to ensure the safety of hydraulic structures.
The safety of hydraulic structures is the properties of hydraulic structures that allow protecting the life, health, and legitimate interests of people, the environment and economic facilities. Safety is ensured based on the following general requirements:
Compliance with the permissible level of risk of accidents of hydraulic structures;
drawing up a safety declaration - a document that defines measures to ensure safety, taking into account the class of a hydraulic structure;
Permitting procedure for the implementation of design, construction and operation;
Continuity of operation;
· formation of safety criteria, equipping with technical means of monitoring the state of hydraulic structures, sufficient qualification of service personnel;
timely implementation of a set of measures that minimize the risk of emergencies;
· Responsibility for actions (inaction), as a result of which the safety of hydraulic structures falls below an acceptable level.
Supervision and control in this area of the national economy is entrusted to the bodies of state supervision over the safety of hydraulic structures. Inspection commissions may be formed to control individual objects.
Water protection. In accordance with the Constitution of the Russian Federation, the water legislation of Russia is under the joint jurisdiction of the Russian Federation and the constituent entities of the Russian Federation. It consists of the Water Code of the Russian Federation and the federal laws and other regulatory legal acts adopted in accordance with it, as well as laws and regulatory legal acts of the constituent entities of the Russian Federation.
According to the Water Code of the Russian Federation, the use of water bodies for drinking and household water supply is a priority. For these purposes, surface and ground water bodies protected from pollution and clogging should be used. Their suitability for drinking and domestic water supply is determined by the sanitary and epidemiological surveillance authorities.
Centralized drinking and domestic water supply of the population is carried out by special organizations that have a license for water use.
According to the Water Code of the Russian Federation, water users are obliged to strive to reduce withdrawals and prevent water losses, prevent pollution, clogging and depletion of water bodies, ensure the conservation temperature regime water objects. Discharge of sewage and drainage waters into water bodies is prohibited:
classified as specially protected;
located in resort areas, in places of mass recreation of the population;
· located in spawning and wintering areas of valuable and specially protected species of fish, in habitats of valuable species of animals and plants listed in the Red Book.
Maintaining surface and groundwater in a state that meets environmental requirements is ensured by the establishment of standards for maximum permissible harmful effects on water bodies. These standards are set based on:
the maximum permissible value of anthropogenic load, the long-term impact of which will not lead to a change in the ecosystem water body;
· the maximum allowable mass of harmful substances that can enter the water body and its catchment area;
· standards for maximum permissible discharges of harmful substances into water bodies.
State accounting of surface and ground waters is a systematic determination and fixation in the prescribed manner of the quantity and quality of water resources available in a given territory. Such accounting is carried out in order to ensure current and future planning for the rational use of water resources, their restoration and protection. State accounting data characterize the state of surface and underground water bodies in terms of quantitative and qualitative indicators, the degree of their study and use. State accounting is carried out in the Russian Federation according to a unified system and is based on accounting data provided by water users, as well as on state monitoring data.
According to the Water Code of the Russian Federation, when placing, designing, reconstructing, commissioning economic and other facilities, as well as when introducing new technological processes, their impact on the state of water bodies and the environment should be taken into account. At the same time, it is also necessary to provide for the creation of closed systems of industrial water supply. Design and construction of direct-flow water supply systems, as a rule, is not allowed. It can be resolved in exceptional cases with a positive conclusion of the state expertise for pre-project and project documentation and the state environmental expertise. Commissioning is prohibited:
economic and other facilities, including filter tanks, waste disposal sites, urban and other landfills, not equipped with devices, treatment facilities that prevent pollution, clogging, resulting in the depletion of water bodies;
· catchment and waste facilities without fish protection devices and devices that provide accounting for the intake and discharge of water;
· livestock farms and other industrial complexes that do not have treatment facilities and sanitary protection zones;
· irrigation, water supply and drainage systems, reservoirs, dams, canals and other hydraulic structures before taking measures to prevent harmful effects on water;
· hydraulic structures without fish protection devices, as well as devices for the passage of flood waters and fish;
· water intake facilities associated with the use of groundwater, without equipping them with water control devices, water metering devices;
water intake and other hydraulic structures without establishing sanitary protection zones and creating observation points for indicators of the state of water bodies;
· Structures and devices for storage and transportation of petroleum, chemical and other substances without equipment to prevent pollution of water bodies and instrumentation to detect leakage of these products.
It is not allowed to commission wastewater irrigation facilities without creating observation points for indicators of the state of water bodies. Prior to the commissioning of reservoirs, measures should be taken to prepare their bed for flooding.
Standardization in the field of water protection. A systematic approach based on the methods of program-target planning and scientifically based forecasting made it possible to develop and improve a set of standards in the field of water protection for: 1) providing water users with water required quality and in sufficient quantities in accordance with established standards; 2) rational use of water; 3) preservation of unique water bodies and their ecosystems in a state closest to natural; 4) compliance with the conditions necessary to maintain the optimal level of reproduction of the biological resources of water, ensuring the possibility of their rational use. Standardization takes into account, first of all, indicators of water quality. The most important water protection measure is the regulation by state standards of the maximum permissible values of pollution indicators of the controlled environment. In particular, a number of standards have been developed that establish general technical requirements for instruments used in the analysis of natural waters. The organizational and methodological standard "Rules for monitoring the quality of water in reservoirs and streams" was approved, which establishes uniform rules for monitoring water quality in terms of physical, chemical and biological indicators.
Purification of domestic sewage. Wastewater treatment is the destruction or removal of certain substances from them, and disinfection is the removal of pathogenic microorganisms.
Sewerage is a complex of engineering structures and sanitary measures that ensure the collection and removal of polluted wastewater from populated areas and industrial enterprises, their purification, neutralization and disinfection. Cities and other settlements discharge 22 billion m3 of sewage per year through sewerage systems. Of these, 76% pass through treatment facilities, including 94% - facilities for complete biological treatment. Through municipal sewerage systems, 13.3 billion m3 of wastewater is annually discharged into surface water bodies, of which 8% of wastewater is treated at treatment facilities to the established standards, and the remaining 92% is discharged contaminated. Of these, 82% are discharged insufficiently purified and 18% without any purification. Most of the wastewater treatment plants are overloaded, and almost half require reconstruction.
Domestic wastewater treatment can be carried out by mechanical and biological methods. During mechanical treatment, wastewater is divided into liquid and solid substances: the liquid part is subjected to biological treatment, which can be natural or artificial. Natural biological treatment is carried out in the fields of filtration and irrigation, in biological ponds, and artificial - on special equipment (biofilters, aeration tanks). Sludge is processed on sludge sites or in digesters.
With a general sewerage system, all types of wastewater from urban areas, including surface runoff, are discharged through one pipeline network. The disadvantage of such a system is periodic discharges into water bodies through storm drains of some part of industrial and domestic wastewater. Currently, the most widely used in our country is the sewerage system, which provides for the construction of two networks of pipelines: through the industrial network, household and industrial wastewater is supplied to treatment facilities, and through the drain, as a rule, without treatment, to the nearest water body rain and melt water, as well as water generated during irrigation and washing of road surfaces are discharged. The most promising from the point of view of protecting water bodies from pollution by surface runoff from cities is a semi-separated sewerage system. With its help, all industrial and domestic waters of the city and most of the surface runoff generated on its territory are diverted for treatment. Over time, the treatment will also receive runoff from pavement washing, most of the meltwater and runoff from rain. Thus, only an insignificant part of melt and rain water will be discharged into water bodies without treatment. In the joint treatment of industrial and domestic wastewater, the content of suspended and floating substances, products that can destroy or clog communications, explosive and combustible substances, as well as temperature are regulated.
Some chemicals affect microorganisms, disrupting their vital functions. Thus, phenol, formaldehyde, ethers and ketones cause denaturation of protoplasmic proteins or destroy cell membranes. Particularly toxic salts of heavy metals, which in descending toxicity can be arranged in a row: mercury, antimony, lead, cesium, cadmium, cobalt, nickel, copper, iron.
For disinfection of wastewater, the dose of chlorine is selected so that the content of Escherichia coli in the water discharged into the reservoir does not exceed 1000 in 1 liter, and the level of residual chlorine is at least 1.5 mg/l with a 30-minute contact or 1 mg/l with 60 minutes of contact. Disinfection is carried out with liquid chlorine, bleach or sodium hypochlorite, obtained on site in electrolyzers. Chlorine management of sewage treatment facilities should allow increasing the estimated dose of chlorine by 1.5 times.
Purification of industrial sewage. Mechanical wastewater treatment ensures the removal of suspended coarse and fine (solid and liquid) impurities. Soluble inorganic compounds are removed from wastewater by reagent methods - neutralization with acids and alkalis, conversion of ions into poorly soluble forms, precipitation of mineral impurities with salts, oxidation and reduction of toxic impurities to slightly toxic ones. Water neutralization can be carried out by mixing acidic and alkaline wastewater. In some cases, chemical treatment can recover valuable compounds, reducing production losses. Often, after chemical treatment, wastewater is subjected to biological treatment.
Currently, wastewater is often re-treated for reuse in industrial water supply. The method of post-treatment of wastewater is selected depending on the specific residual water pollution. Thus, for the treatment of highly mineralized effluents, the thermal desalination method is used, in which the distillate obtained from effluents is used as demineralized water. Reuse of treated wastewater reduces the consumption of fresh water from sources by 20-25 times.
Scientists from Los Alamos National Laboratory (USA), together with researchers from Florida International University (Miami) and the University of Miami, are working on a way to destroy hazardous liquid waste using an electron accelerator. An experiment conducted at a municipal waste treatment plant in Dade County, Florida, showed that hazardous substances such as benzene, phenol and trichlorethylene can be destroyed by this method. The cost of electron beam treatment of 1000 liters of waste will be about $3, which is less than when cleaning liquid waste using activated carbon filters (including the cost of recovering contaminated filter material).
Monitoring of water bodies. As part of the protection of the hydrosphere, on March 14, 1997, the government of the Russian Federation approved the "Regulations on the introduction of state monitoring of water bodies." State monitoring of water bodies is carried out by the Ministry of Natural Resources, the Federal Service for Hydrometeorology and Environmental Monitoring (for surface water bodies) and other specially authorized state bodies in the field of environmental protection. State monitoring includes:
· Regular monitoring of the state of water bodies, quantitative and qualitative indicators of surface and groundwater;
collection, storage, replenishment and processing of observational data;
creation and maintenance of data banks;
· Assessment and forecasting of changes in the state of water bodies, quantitative indicators of surface and groundwater.
State monitoring of water bodies is an integral part of the state environmental monitoring system and consists of:
1. Monitoring of surface water bodies on land and seas;
2. Monitoring of underground water bodies;
3. Monitoring of water management systems and structures.
The order of location and the number of observation points, as well as the list of observed indicators and pollutants, the timing of observations are primarily determined by the level of development of industry and agriculture in the controlled area.
The schedule of water sampling at water bodies depends on the importance of the observation point for the national economy and the variability of the concentrations of analytes. In water bodies affected by enterprises, where the production cycle is relatively stable, the timing of observations depends mainly on the hydrological regime of the controlled object. If the work of the enterprise is seasonal, the frequency of control depends on the mode of production.
It should be noted that traditional methods of observation and control have one fundamental drawback - they are not operational and, in addition, characterize the composition of pollution of environmental objects only at the time of sampling. What happens between sampling periods can only be guessed at. In addition, laboratory tests take considerable time. More effective is the control over water quality, carried out with the help of automatic devices. Electrical sensors continuously measure contaminant concentrations, enabling quick decision making in the event of adverse impacts on water sources. The automated station can measure and control water quality indicators (degree of acidity or alkalinity, electrical conductivity, temperature, turbidity, dissolved oxygen content), water level, as well as the presence of suspended solids and certain metal ions. Comparison of the analysis of water samples taken by several stations located along the river makes it possible to identify the direct culprit of pollution. This is especially important during salvo discharges of harmful substances, when timely Taken measures can localize or destroy pollution in a relatively short time.
For operational monitoring of water quality in those points where there is no automatic stations, mobile laboratories operate as part of the system.
Conclusion.
The logic of the development of life on Earth defines human activity as the main factor, and the biosphere can exist without a person, but a person cannot exist without the biosphere. Clean water is a factor in the existence of the biosphere. The next generations will not forgive us for depriving them of the opportunity to enjoy the pristine nature. Preserving the harmony of man and nature is the main task facing the present generation. This requires a change in many previously established ideas about the commensurability of human values. It is necessary to develop an “environmental consciousness” in every person, which will determine the choice of options for technologies, the construction of enterprises and the use of natural resources.
One of the main tasks of modern education is the formation of an ecological way of thinking. Thus, in 1991, the government of the Republic of Belarus approved the Republican program for education in the field of the environment. It defines the goals and principles of the organization environmental education in the field of environmental protection. An important point is the fact that the priority of environmental education, the mandatory introduction of environmental disciplines in all educational institutions enshrined in the laws of the Republic of Belarus "On Education" and "On Environmental Protection". From the slogan “Take everything from nature”, a transition to the slogan “Nature is our home” is necessary.
Bibliography
1. Yu. V. Novikov. Ecology, environment and man. Moscow, Fair, 1999.
2. A. O. Selivanov. Changeable hydrosphere of the Earth. Moscow, Knowledge, 1990.
3. O. A. Spangler. A word about water. Leningrad, Gidrometioizdat, 1980.
4. Environmental protection - a guide.
Properties of water and global water exchange.
The hydrosphere plays a crucial role in maintaining a relatively constant climate on the planet, since it performs the following essential functions:
§ acts as a global heat accumulator in the Earth's ecosystem (the heat capacity of water is 3300 times higher than that of air, therefore, surface ocean waters are the main accumulator and distributor of solar energy, ensuring the constancy of the average planetary temperature of the atmosphere);
§ Produces almost half of all atmospheric oxygen due to phytoplankton living in the World Ocean.
The aquatic environment is used by man for fishing and other seafood, collecting plants, extracting underwater deposits from ore (manganese, nickel, cobalt) and oil production on the shelf, transporting goods and passengers. In production and economic activities, a person uses water for cleaning, washing, cooling equipment and materials, watering plants, hydrotransportation, providing specific processes, for example, generating electricity, etc.
Natural waters are divided into two large classes: fresh and salty. Fresh water is called water, 1 kg of which contains no more than 1 g of salts. The rest of the natural waters are classified as saline, which account for 97.5% of the total world water supply.
The concentration of salts dissolved in water determines the degree of its salinity (hardness). In ocean waters, the concentration of dissolved substances is, on average, 175 times higher than that in the waters of rivers and lakes (it does not follow from this that there cannot be strongly desalinated sea waters and highly saline lake and even river waters).
Despite the huge reserves of natural waters on Earth, only a small part of them is available and suitable for practical use. First of all, it is fresh water. If we add another 300 tons of water to the annual human consumption of 60 tons of fresh water needed to meet other vital needs, then the annual consumption of fresh water per inhabitant of the planet will be 360 tons / year. It follows from this that the limited one-time fresh water reserves could be exhausted within 3-4 months. However, fresh water reserves on Earth are continuously replenished under the influence of natural forces and, above all, global water exchange.
Global water exchange includes both water exchange in the ocean-continent system, when water, evaporating from the ocean surface, is transported by winds to the continents and returns to the ocean with river runoff, and local water cycles in individual landscapes, when water evaporation leads to cloudiness and precipitation.
The solar energy spent on the evaporation of water, after precipitation, is converted into the kinetic energy of rivers and streams. This process consumes a very large amount of solar energy, according to some estimates, from 20% to a third of what the Earth receives from the Sun.
There is less precipitation over the World Ocean than over the continents, but for the planet as a whole, precipitation is balanced. The balance of water between continents and oceans is maintained mainly by runoff. At the same time, evaporation accounts for up to 65%, and surface runoff - up to 35% of the water involved in the circulation.
Evaporation of water is the most important process in its circulation. Water evaporates from the surface of both oceans and soil, as well as plant leaves after absorption by roots. The amount of water transpired by plants is significant. All terrestrial vegetation releases into the atmosphere from 27 to 30% of the total amount of moisture received by the land of the planet in the form of precipitation per year.
The development of civilization changes the natural cycle of water, primarily due to a change in the balance of transpired water, as well as the formation of such an intermediate link as technical water consumption. Special Role in this process belongs to irrigation - artificial moistening of the soil and plant surfaces by supplying water from a water source in order to provide plants with moisture, washing the soil and regulating their salt regime.
70% of fresh water consumed by people is used in agriculture. At the same time, 60% of the water used for irrigation does not reach the fields.
The total area of irrigated lands in the world is more than 230 million hectares. Irrigated land is at least twice as productive as non-irrigated land: accounting for one sixth of cultivated land, it produces one third of all crops.
It should be especially taken into account that the intensity of transpired moisture depends on the type of vegetation. Thus, during the growing season, wheat transpires 6,000 tons of water from 1 ha of irrigated land, rice - 4.6 times more, and cotton - 6.7 times.
To save water for irrigation, it is necessary to apply progressive methods. The most economical and efficient method of irrigation is subsoil drip, when water is supplied to the root system of plants through a system of special pipes laid in the soil.
Hydrosphere pollution
The most dangerous pollutants of the hydrosphere in terms of their impact on natural ecosystems are hydrocarbons (crude oil, oil products), toxic metals, chlorinated hydrocarbons (primarily pesticides), and radioactive substances. Of the other pollutants of the hydrosphere, it is necessary to mention detergents (detergents) and phenols.
Pollution of natural waters by oil and oil products. The most common and harmful pollutants include oil, the annual flow of which into the seas and oceans, according to the UN, reaches 6 ... 7 million tons. A further increase in oil pollution is expected due to the constant increase in its production, especially on the continental shelf.
Crude oil is a mixture of chemicals containing 200-300 components. Oil consists of 50-98% hydrocarbons, contains up to 4% sulfur, up to 1% nitrogen and oxygen. Petroleum hydrocarbons (petroleum products) are divided into three groups: alkanes (25%); cycloalkanes (naphthenes) (30-60%); aromatic and polyaromatic (PAH) (up to 5%). The most toxic part are PAHs. The biosphere contains several dozen PAHs (in total, this group contains more than 200 compounds). The most common and toxic is 3,4-benz(a)pyrene (BP) (besides anthracene, pyrene, chrysene, etc.). The background level of PAHs is 1 ng/l, in the Baltic Sea - 100 ng/l. The level of PAH content in bottom sediments is especially high.
The main sources of oil pollution of the marine environment: transportation; removal by rivers; industrial and municipal waste, waste from oil refineries. There are also natural sources of oil pollution. One of the main anthropogenic sources is maritime transport, primarily tanker transport. The world has a giant tanker fleet with a total capacity of more than 120 million gross register tons, which is over a third of the capacity of all marine vehicles. Now there are 230 ships with a carrying capacity of 200 to 700 thousand tons each. This poses a colossal potential danger to the waters of the oceans. According to known data, due to accidents on tankers, approximately 5% of all transported oil enters the seas and oceans. It has been calculated that if 200,000 tons of oil enters the Baltic Sea, it will be turned into a biological desert.
A huge amount of oil enters the sea as a result of the discharge of washing, ballast and bilge (hold) water from ships, as well as losses during loading and unloading of tankers. For these reasons, about 3 million tons of oil end up in the seas and oceans every year. At the same time, port territories, port water areas, coastal areas and areas of intensive navigation are mainly polluted.
At the beginning of the third millennium, underwater wells will produce 50% of the world's oil. During offshore oil production, pollution of the marine environment is possible due to accidents, as well as small oil leaks (estimated at 0.1 million tons annually). Obviously, this source represents a huge potential danger, and its role in the formation of oil pollution of the seas and oceans will increase over time.
The source of oil pollution of waters is the coastal industry, and primarily oil refineries. Although wastewater from industrial enterprises is being treated, complete purification of wastewater from oil and oil products cannot be achieved.
A large amount of oil products enters the ocean basins from the atmosphere. For example, internal combustion engines, which are equipped with various vehicles, emit more than 50 million tons of various hydrocarbons into the air per year.
As noted above, in addition to technogenic sources, there are also natural ones. Natural seepages of oil are formed in places where it seeps from oil-bearing layers through the earth's crust. Such exits are known off the coast of Southern California, in the Mexican and Persian Gulfs, and the Caribbean Sea. The rate of oil inflow from natural outlets is usually low, therefore, a relatively small amount of oil hydrocarbons enters the seas and oceans in this way, and the bulk of the pollution of the World Ocean (more than 90%) is supplied by sources of anthropogenic origin.
The fields of oil pollution, which form local zones, remain stable in time, so oceanic circulations play a huge role in their distribution. It is they who carry oil pollution to the cleanest regions of the World Ocean, including the Arctic Ocean.
Oil products entering the water are degraded as a result of chemical, photochemical and bacterial decomposition, as well as the activity of some marine organisms and higher plants. However, the "process" of natural neutralization of petroleum products is quite lengthy and can take from one to several months.
When mixed with water, oil forms an emulsion of two types: direct "oil in water" and reverse "water in oil". Direct emulsions, composed of oil droplets up to 0.5 µm in diameter, are less stable and are characteristic of oil containing surfactants. When volatile fractions are removed, oil forms viscous inverse emulsions, which can remain on the surface, be carried by the current, be washed ashore and settle to the bottom. The greatest danger in terms of their consequences is represented by oil films that form on the water surface and reduce the thermal conductivity and heat capacity of the upper water layer. The presence of an oil film strongly affects the evaporation process. So, on calm water, due to a thin layer of oil, evaporation decreases by 1.5 times, and at wind speeds up to 6 ... 8 m / s - by 60%, since the films serve as a barrier for water molecules and reduce the aerodynamic roughness of the water surface. It has been experimentally established that 45 tons of water evaporates from the surface of the ocean in one square mile in the presence of an oil film, while in the absence of a film - 97 tons. saturated with water vapor.
Under natural conditions, oxygen and carbon dioxide are continuously exchanged through the atmosphere-water surface interface, the intensity of which is greatly reduced in the presence of an oil film. Under certain conditions, oil films lower the temperature of the surface layer of water (not lower than +4°C), which leads to an increase in its density and, as a result, upper layer water sinks into the depths, bringing oil pollution there. In shallow basins, surface contaminated layers can sink to the bottom and form near-bottom waters containing a significant amount of oil. The formation of such polluted bottom layers is especially probable during the period of autumn water cooling.
Thus, oil films are the technogenic factor that affects the formation and course of hydrological and hydrochemical processes in the surface water layers of the seas and oceans.
Oil pollution also affects living organisms by shielding solar radiation and slowing down the renewal of oxygen in water. As a result, plankton, the main food of marine life, ceases to multiply. Thick oil films are often the cause of the death of seabirds. Oil adversely affects the physiological processes occurring in living organisms, causes pathological changes in tissues and organs, disrupts the functioning of the enzymatic apparatus and the nervous system.
Pollution of high-latitude waters is especially dangerous, where, due to low temperatures, oil products practically do not decompose and are, as it were, "preserved" by ice, so oil pollution can cause serious damage to the environment of the Arctic and Antarctic.
Pollution of natural waters with heavy metals. Under the conditions of active anthropogenic activity, the pollution of oceanic waters with heavy metals has become a particularly acute problem. The group of heavy metals with a density above 4.5 g/cm3 combines more than 30 elements of the periodic system. The most toxic metals include primarily Pb (lead), Hg (mercury), Cd (cadmium), As (arsenic), Zn (zinc), Se (selenium), as well as Fe, Al, Cu, Mn, Ni , Co, Sn, Ti, Bi, Mo, V, Ag, Cr, Te. They are widely used in various industrial productions, therefore, despite the treatment measures, the content of heavy metals and their compounds in industrial wastewater is quite high. Large masses of these compounds enter the ocean through the atmosphere.
The main sources of pollution of natural waters with heavy metals are:
Industrial discharges;
Atmospheric precipitation, mainly rain (heavy metals enter the atmosphere as a result of fuel combustion and volcanic eruptions; the content of toxic elements of atmospheric origin can reach 25-100%);
Water transport (ship hulls are coated with paints containing Hg, As, Cu, Cr, Pb, Zn, Cd to prevent algae and marine organisms from fouling the hulls);
Leaching from soils into which heavy metals (HMs) enter from fertilizers and pesticides (inorganic fertilizers contain HMs as impurities).
A large percentage of HM is contained in sludge, which is one of the main organic fertilizers. Pesticides also contain HMs, which are often used as catalysts for their synthesis.
For marine biocenoses, mercury, lead and cadmium are the most dangerous, since they remain toxic indefinitely. For example, mercury-containing compounds (especially methylmercury) are the strongest poisons that act on nervous system pose a threat to the life of all living things. In the 50s–60s of the XX century. in the area of Minomata Bay (Japan), mass poisoning was registered, the victims of which were tens of thousands of people who ate infected fish. The cause of the contamination was an enterprise that dumped mercury into the water of the bay.
Up to 2 million tons of lead, up to 20 thousand tons of cadmium and up to 10 thousand tons of mercury enter the World Ocean annually. Coastal waters and inland seas have the highest pollution levels. The atmosphere also plays a significant role in the pollution of the oceans. Thus, up to 30% of all mercury and 50% of lead entering the ocean annually is transported through the atmosphere. Once in sea water, heavy metals are concentrated mainly in the surface film, in the bottom sediment and in biota, while in the water itself they remain only in relatively small concentrations. Here, the surface film is especially significant, which usually extends to a depth of 50–500 µm. It is in this region that all equilibrium processes of mass transfer between water and the atmosphere take place.
The activity of accumulation of various substances in living organisms from the environment is expressed by the corresponding coefficients. Thus, the ratio of the content of a substance in the tissues of hydrobionts (inhabitants of the aquatic environment) to its concentration in water is called the accumulation coefficient. For example, in daphnia, the accumulation coefficient of methylmercury is 4 thousand, in plankton the accumulation coefficient of lead is 12 thousand, cobalt is 16 thousand, and copper is 90 thousand. Researchers say that for any chemical element there is at least one type of plankton capable of concentrate it.
Large amounts of heavy metals are concentrated in bottom sediments. This is confirmed by the fact that the concentration of metals in sediment can be several orders of magnitude higher than in water.
Pollution of natural waters with pesticides and other chemical compounds. Pesticides are a class of synthesized organic substances that have toxic properties and are divided into groups according to their purpose:
Insecticides - to kill insects;
Herbicides - against weeds;
Fungicides - against fungi;
Specific - against rats, snails, etc.
The quantity of insecticides considerably exceeds the quantity of herbicides.
Based on the chemical composition of pesticides, 3 large groups can be distinguished:
Chlorinated hydrocarbons;
Phosphorus organic compounds;
The solubility and stability of pesticides in water are different. Despite the large removal of pesticides into the hydrosphere, their concentration is relatively low: ~10-7% in fresh and ~10-9% in ocean waters. However, even such low concentrations are dangerous for the life of living organisms.
The most common organochlorine pesticides are:
Aromatic: DDT and its metabolites - DDD and DDE;
Aliphatic and alicyclic - lindane or hexachlorocyclohexane, hexachloran;
Chlorinated products of diene synthesis.
All of these compounds are classified as insecticides; quite resistant to decomposition, and, therefore, accumulate in the environment and organisms (especially in molluscs, found in dolphins). Chlorinated hydrocarbons also include a very important class of compounds - polychlorinated biphenyls (PCBs). They are obtained by chlorination of biphenyls.
The analysis of chlorine-containing compounds showed that all of them contain thousandths of dioxins as impurities, i.e. the latter are formed as by-products of most chemical industries. These various derivatives of aromatic chlorinated ethers are supertoxicants. PCBs and dioxins suppress the immune system.
Phosphorus organic pesticides (OP) - esters of phosphoric, thiophosphoric and dithiophosphoric acids, belong to insecticides. Their advantage is low chemical resistance.
Detergents. These are detergents, the main components of which are surface-active substances (surfactants), (additives - enzymes, bleaches, fragrances, corrosion inhibitors, etc.).
In lightly polluted waters, the concentration of surfactants ranges from thousandths to hundredths of mg/l. Surfactants are concentrated in the surface film, forming a monolayer. Surfactants do not belong to highly toxic substances, their MPC is ~ 0.5-2 mg/l. At the same time, they are extremely common due to their widespread use in everyday life and industry. They can enhance the adverse effects of other pollutants that are toxicants: increase their solubility in water, form stable emulsions, for example; oil products.
Phenols. Compounds of this class are usually divided into:
Volatile with steam (phenol, cresols, xylenols, etc.;
Non-volatile (polyatomic, such as resorcinol, pyrogallol, etc.). Sources of phenols can be of natural origin - metabolism of aquatic organisms, degradation of organic matter, and anthropogenic, for example, antiseptics. The content of phenols in waters usually does not exceed 20 µg/l.
It is often more convenient to group the numerous sources of pollution of the World Ocean mentioned above according to the “environmental” principle, in which the sources are divided into three large groups:
§ marine - ships for various purposes (including warships) and other installations and devices operated in the marine environment; pipelines, installations and devices used in the exploration and development of natural resources of the seabed and its subsoil;
§ terrestrial - rivers and other water systems communicating with the seas, where pollutants enter as a result of discharges of waste and heated waters by industrial enterprises, or with groundwater contaminated from burials of especially harmful substances (including radioactive waste), as well as various onshore facilities discharging into the sea;
§ Atmospheric - various industrial enterprises, vehicles and other objects that emit harmful gaseous waste into the atmosphere, a large amount of which from the atmosphere enters the ocean basins.
It has been established that the natural possibilities of neutralizing pollution in the ocean are practically exhausted today. The overall assessment of the state of the ocean is more alarming than the assessment of the state of the atmosphere. To maintain the ecological balance of the marine spaces of our planet, international cooperation is very important, including for the development of the norms of modern international law. The natural environment is one and indivisible; changes in its state cannot be limited to any particular space. No state, no matter how economic and scientific and technical potential it may have, can solve all the problems associated with the preservation and improvement of the state of the environment. International specialization and coordination in science and technology can accelerate the creation of low-waste processes and effective anti-pollution devices.
Depletion of continental waters.
In general, inland waters are usually divided as follows:
surface,
soil,
Underground.
Fresh waters are distributed on the Earth's surface extremely unevenly. Thus, in Europe and Asia, where 70% of the world's population lives, only 39% of the world's river waters are concentrated. On the territory of Russia, 82% of the river flow falls on the northern regions of the country, which, due to climatic conditions, are unsuitable for the development of agriculture and are significantly less populated than the southern regions, which are economically more developed, but are experiencing a shortage of fresh water.
The uneven distribution of precipitation and the ever-increasing pollution of the hydrosphere have led to the fact that in many countries there is a shortage of fresh water.
There is a depletion of the most valuable sources of fresh water available to man - groundwater. The depletion of the upper horizons of groundwater is observed in the USA, Germany, Great Britain, the Netherlands, and Japan. Depletion of the artesian basin under the Kuban Plain was reported. The level of artesian waters near Krasnodar is decreasing every year.
The most serious concern is the state of small rivers. The uncontrolled use of water, the destruction of water protection forest belts and the drainage of raised bogs led to the massive death of small rivers. According to estimates by German biologists, half of the geographic Maps the country of streams and ponds dried up; 90% of springs and swamps with springs gushing into them no longer exist.
However, the most tangible blow to fresh water was dealt modern technologies, as under their influence the pollution of rivers and lakes with industrial and domestic waste, toxic substances is growing. Only the industry annually discharges into the rivers more than 160 km3 of industrial effluents - untreated or insufficiently treated. They pollute over 4 thousand km3 of river waters, i.e. about 10% of the total river runoff. In industrialized countries, this figure reaches 30% or more.
At present, most of the world's rivers in their channels no longer carry fresh water suitable for water supply to the population, but diluted wastewater from cities, industrial enterprises, livestock farms, etc. In the rivers, instead of pure water, there are complex solutions and suspensions of harmful chemicals and bacteria.
The ill-considered use of water, which exceeds the possibilities of its restoration, as well as its intense pollution, lead to the transformation into deserts of large areas of the continents. The once full-flowing clean rivers and lakes become shallow all the time, blue-green algae multiply in them, and the water becomes unsuitable for drinking or for the life of fish and other aquatic organisms.
According to the World Health Organization, up to 80% of all diseases associated with the quality of the environment are the result of the consumption of dirty water by the population.
Almost 2.5 billion people on the planet suffer from dysentery, hepatitis, diarrhea and other diseases associated with water pollution.
Use of fresh water
All sectors of the national economy that use water resources are divided into two categories:
Water users are industries that use water bodies for various purposes, but do not take irretrievable water. These include hydropower, water transport, fisheries, utility services for household and drinking supplies.
Water consumers are industries that take water from reservoirs, and part of it is used irrevocably. The largest water consumers are thermal power engineering (especially nuclear power plants), Agriculture, and from the industry - chemical and metallurgical.
A modern city with a population of 1 million people consumes 300 thousand m3 of water per day, of which 75 ... 80% turn into wastewater.
There is the following classification of fresh water according to its intended purpose:
Drinking water - water in which bacteriological, organoleptic indicators and indicators of toxic chemicals are within the limits of drinking water supply norms;
Mineral water - water, the composition of which meets the medical requirements;
Thermal energy water - thermal water, the thermal energy resources of which can be used in any sector of the national economy;
Industrial water - water, the component composition and resources of which are sufficient to extract these components on an industrial scale;
Technical water - any water, except for the above, suitable for use in the national economy.
At the same time, the following types of industrial water are distinguished:
Domestic water - water used for domestic and sanitary purposes by the population, as well as laundries, baths, canteens, hospitals, etc.;
Irrigation water - water used to irrigate land and irrigate agricultural plants;
Process water - water that is in direct contact with products and products and is subdivided, in turn, into medium-forming, washing and reaction water (medium-forming water is used for dissolution and formation of pulps, in the enrichment and processing of ores, hydrotransport of products and production wastes; washing water - for washing gaseous (absorption), liquid (extraction) and solid products and products, and reactionary - as part of reagents, during distillation and similar processes);
Energy water is water used to produce steam and heat rooms, equipment and environments, as well as to cool liquid and gaseous products in heat exchangers, and solids directly.
Energy water can be recycled and make-up (additional). Water is often used to cool liquid and gaseous products in heat exchangers. Energy water does not come into contact with material flows and is not polluted, but only heated. In industry, 65...80% of the water consumption is consumed for cooling.
Water quality
This characteristic of the composition and properties of water determines its suitability for specific uses. The following water indicators are distinguished, regulated by the relevant documents:
Organoleptic;
Hydrochemical;
Microbiological;
Determination of organoleptic indicators is mandatory for any study of water. These include color, smell, taste and aftertaste, turbidity and foaminess.
Hydrochemical indicators occupy a significant place in the totality of data on the state of a water body, while they can be determined by field or laboratory methods. For field methods in Russia, a wide range of test kits is produced that allow performing a unified analysis directly at the water body. Hydrochemical indicators of water quality determined by field methods include: pH value (pH), dissolved oxygen, mineralization (carbonates and hydrocarbonates, sulfates, chlorides, dry residue, total hardness, calcium and magnesium, sodium and potassium cations), biogenic elements (nitrates, phosphates, ammonium, nitrites), fluorides, total iron.
pH value- one of the most informative characteristics. The pH value in natural waters is determined by the quantitative ratio of CO 2 dissolved in water, bicarbonate and carbonate ions; processes of photosynthesis (consumption of CO 2 by aquatic vegetation) and decay of organic substances; dissociation of substances of humic nature (marsh waters have low pH); hydrolysis of aqua-ions of metals. The pH value fluctuates: in river waters in the range of 6.5-8.5, in atmospheric precipitation - 4.6-6.1; in swamps - 5.5-6.0; in ocean waters - 7.9-8.3; in mines and mines - ~ 1; in soda lakes - ~ 10. The pH value has a significant impact on the form of existence of substances in aquatic ecosystems.
An integral assessment of water quality is usually carried out according to hydrochemical indicators, if they are sufficient, and can be carried out in several ways.
In the general case, if there is data on several estimated indicators, it is possible to calculate the sum of the reduced concentrations of parameters to the MPC (principle of summation of effects). In this case, the criterion of water quality is the value
where FROM f i- the actual concentration of the i-th substance in the water of the reservoir.
If data on a sufficient number of indicators are available, it is possible to estimate the water pollution index (WPI), which is calculated as the sum of the actual values of quality indicators reduced to MPC for 6 main water pollutants:
(3.2)
where C i- the average value of the determined indicator for the observation period (for hydrochemical monitoring, this is the average value for the year); MPCi – maximum allowable concentration of a pollutant; 6 - strictly limited (limited) number of indicators used for calculation.
As an integral characteristic of surface water pollution, water quality classes are used, which are established depending on the WPI value (see Table P.2 of Appendix 2).
When calculating the WPI, six indicators necessarily include the concentration of DO (dissolved oxygen) and the value of BOD5, as well as 4 more indicators that are the most unfavorable for a given reservoir (water), i.e. having the highest relative concentrations (ratio C i/ MPC i).
Dissolved oxygen is always contained in natural water. In principle, all gases contained in the atmosphere: O 2 , H 2 S, N 2 CO 2 and others are present in the hydrosphere. Gas exchange (phase equilibrium) is carried out through the surface film. The main sources of dissolved oxygen (usual content ~ 14 mg/l) are the atmosphere, photosynthetic activity, rain and snow water supersaturated with oxygen.
Biochemical oxygen demand (BOD) gives a relative idea of the content of easily oxidizable organic substances and can characterize the amount of organic waste or water quality. To assess this parameter, the oxygen dissolved in the sample is determined, then it is incubated for at least 5 days in a special bottle in the dark. As a result of the vital activity of bacteria, oxygen is spent on the oxidation of organic compounds present in the water. The loss of dissolved oxygen over a certain period of time characterizes the BOD.
Determining the content of chemical toxins (pesticides, petroleum products, heavy metals, surfactants, etc.) improves the quality of the assessment, but it is fraught with difficulties, since the analysis requires special laboratory equipment, complex methods or instruments, highly qualified personnel, etc. However, the assessment water quality for this group of indicators or for some of them, in some cases, is possible if you use the results of water analyzes obtained by special services - environmental, sanitary, fisheries, etc.
General characteristics of wastewater pollution. The term "wastewater" combines waters of different origin, composition and properties, which, after human use, received additional pollution and changed their quality.
By their nature, wastewater pollution is divided into organic, inorganic and biological. According to the classification of L.A. Kulsky, all sewage impurities, regardless of their nature, are divided into four groups (Table 3.1).
Table 3.1
The main groups of impurities according to the phase-dispersion state
|
Gouppa |
Main characteristic |
Nature of impurities |
impact |
|
Water-insoluble coarse impurities that form suspensions and emulsions. Form heterogeneous kinetically unstable systems with water |
Insoluble impurities of organic and inorganic nature; microorganisms |
Separation from water under the influence of gravitational or centrifugal forces |
|
|
Colloidal degree of dispersion with a particle size of not more than 10-6cm. hydrophilic and hydrophobic colloidal impurities of this group form a heterogeneous system with water with special molecular kinetic properties |
colloidal systems; macromolecular compounds; from microorganisms - viruses |
Destruction of the Aggregative Stability of Impurities |
|
|
Molecular degree of dispersion with a particle size of not more than 10-7cm. Form homogeneous systems in water |
Diverse in composition; indicators are largely determined by: smell, color, MIC and COD |
Biological and physico-chemical methods |
|
|
Ionic degree of dispersion with a particle size of not more than 10-8 cm |
Bases, acids and their salts |
Complex physicochemical methods: ion exchange, membrane separation |
On fig. 3.1 shows the main methods of wastewater treatment, effective use which allows for the protection of the hydrosphere.
Mechanical cleaning methods. The separation of insoluble impurities is based on two different principles:
1) under the action of gravity and / or centrifugal forces (depending on the size and specific gravity of the particles). Centrifugal forces increase separation. Preliminary (coarse) wastewater treatment is based on this principle. The degree of purification is from 40% to 70% (with preliminary reagent treatment, the efficiency of removing impurities increases to 90%);
Rice. 3.1.
2) filtering and straining, when water containing impurities is passed through a filter material that is permeable to liquid and impermeable to solid particles. This method is used for deep treatment (treatment) of wastewater. The degree of purification reaches 99%. The process is accompanied by high energy costs.
Independently mechanical cleaning methods can be used if the volume of wastewater is much less than the volume of the reservoir, or when, according to production requirements, purified mechanically industrial waters can be used in technological processes at the enterprise (factory or workshop water circulation). On fig. 3.2 shows the main devices that are used for mechanical wastewater treatment.
1. Settling is the simplest, least energy-intensive and cheap method of separating suspended solids from wastewater with a density different from that of water. For successful separation, it is necessary to create a laminar flow regime in the treatment plant. Under the action of gravity, particles of pollution settle to the bottom of the structure or float to its surface. The use of hydrocyclones and centrifuges increases separation efficiency.
Rice. 3.2.
For the treatment of domestic wastewater, sedimentation tanks are usually placed in front of:
- gratings and sieves, which are designed to trap large contaminants, mainly of organic origin;
- sand traps, which serve to trap impurities of mineral origin, mainly sand. Detain particles with a diameter of more than 0.25 mm.
Sand traps must be designed with a throughput capacity of treatment facilities over 100 m 3 /day.
Vertical settlers - these are, as a rule, cylindrical (or square in plan) tanks with a conical bottom with a diameter of up to 10 m and a capacity of up to 3000 m 3 /day. The movement of clarified water in the settling tanks occurs in the vertical direction - from the bottom up. Suspended particles settle in the upward flow of water. Estimated upstream velocity should not exceed 0.5-0.6 mm/s; the height of the sedimentation zone is usually 4-5 m. The collection of clarified water is carried out using peripheral or radial gutters through the weir. The sediment that has fallen into the silt part of the sump is removed through the silt pipe. The volume of the silt part is calculated for a two-day volume of sediment. The slope of the conical part of the bottom of the sump is assumed to be at least 45-50° to ensure the sliding of the sediment.
Dignity vertical settling tanks is the simplicity of their design and ease of use, disadvantage - large depth of structures, which limits their maximum diameter of 9 m, low efficiency of clarification.
The efficiency of wastewater clarification in vertical settling tanks is low (usually does not exceed 40% in terms of suspended solids removal), which is 10-20% lower than in horizontal and radial settling tanks.
Vertical settling tanks are used as primary in general plant treatment facilities.
Horizontal sedimentation tanks - rectangular tanks with a depth of the sedimentation zone (H) equal to 1.5-4.0 m, a length of 8-12 N (sometimes up to 20 N), with a corridor width of 3-6 m. The sediment is removed from them hydraulically or by moving scrapers . Uniform distribution of waste water across the width of the sump is carried out using a transverse tray with a weir or a perforated partition. To retain floating substances, a partition is installed at the outlet of the sump, immersed in water by 0.25 m.
The horizontal speed of water movement in the sump usually does not exceed 10-12 mm/s, and for wastewater containing flakes of aluminum and iron hydroxides, it is 3-5 mm/s; the duration of water settling is 1-3 hours. During coagulation wastewater treatment, these sedimentation tanks are equipped with built-in flocculation chambers.
Virtues horizontal clarifiers are their relatively high volume utilization (TO = 0.5) and the achieved clarification effect is 50-60%, as well as the possibility of their compact placement with other treatment facilities. disadvantages are: unsatisfactory reliability of the mechanisms used in them for raking sediments of the trolley or chain type, especially in winter; capital costs for the construction of horizontal sedimentation tanks are higher than for radial ones, due to the higher (by 30-40%) consumption of reinforced concrete per unit of construction volume.
Radial settling tanks - these are usually round reservoirs with a diameter of up to 60 m (sometimes more than 100 m), in which water moves along the radius from the center to the periphery. The speed of water movement is variable: in the center - maximum, and on the periphery - minimum. Waste water enters the sump through a central separation device, and clarified water is collected in a circular peripheral chute. Radial settling tanks are equipped with movable farms with a central or peripheral drive. The depth of the flowing part of the sump is 1.5-5 m, and the ratio of diameter to depth is from 6 to 30 m. The residence time of waste water in the sump is 1.5-2 hours. The clarification efficiency is 50-55%. They have quite a lot of productivity.
Advantages radial settling tanks - a round shape that allows you to reduce the required thickness of wall panels through the use of high-strength prestressed reinforcement, which reduces their specific material consumption. The rotating farm provides simplicity of their operation. Significant drawback radial clarifiers - increased speed in the water outlet zone, which leads to inefficient use of a significant part of the clarifier volume. This disadvantage is largely eliminated in radial sedimentation tanks with a peripheral supply of waste water. The collection of clarified water is carried out using an annular tray located in the center of the sump. This design of the sump allows 1.3-1.5 times to increase its throughput.
Thin layer settling tanks characterized by a shallow depth of sedimentation. The use of thin-layer settling tanks can make it possible to increase the water consumption in proportion to the number of elementary clarifiers (number of tiers), or to proportionally reduce the dimensions of the original clarifier.
According to the scheme of movement of water and sediment, thin-layer settling tanks are divided into settling tanks:
- with cross pattern- the separated sediment moves perpendicular to the movement of the clarified water flow (the most rational design);
- countercurrent circuit- the selected precipitate is removed in the direction opposite to the movement of the clarified water flow;
- once-through scheme- the separated precipitate is removed in the direction coinciding with the direction of the clarified water flow. By design, thin-layer sedimentation tanks are divided into
tubular and plate. The working element of the tubular sump is a tube with a diameter of 2.5-5 cm, a length of 60-100 cm. The slope of the tubes is from 5 to 60°. Apparatuses with a small inclination of the pipe operate in a periodic mode, and with a large inclination - in a continuous mode. Water is supplied from the bottom up. The uniformity of the supply and distribution of waste water over the cross section of the tubes and the laminar flow of water in the tubes determine the efficiency of clarification of waste water in tubular thin-layer sedimentation tanks. The sediment slides down the inclined planes and is removed. Tubular settling tanks are used with a capacity of up to 170 thousand m 3 /day.
Lamellar thin-layer settling tanks consist of a number of inclined plates installed in parallel. The water in the sump moves parallel to the plates. Such settling tanks are promising for use as secondary brighteners.
Dignity thin-layer clarifiers lies in their efficiency due to the small volume and the possibility of using plastics, which simplifies their manufacture, reduces weight and reduces cost. The possibility of retrofitting existing settling tanks by installing tubular or plate tanks is also an important advantage. Flaws- demanding on the uniformity of the supply of waste water, it is difficult to remove sediment from the shelves.
2. Separation in the field of centrifugal forces. To release suspended solids in the field of centrifugal forces, open, pressure, multi-tiered hydrocyclones and centrifuges can be used. A significant advantage of open hydrocyclones over pressure ones is their high productivity and small head losses, usually not exceeding 0.5 m. less than 200 m 3 / h per unit. Such wastewater includes scaling wastewater from rolling mills. Water is fed tangentially into the cylindrical part of the apparatus.
Open hydrocyclones often work in conjunction with other facilities for the mechanical treatment of industrial wastewater, being its first stage.
In a pressure hydrocyclone, the jet of the treated liquid enters the cylindrical part through a tangential nozzle and receives a rotational motion. The design dimensions of pressure hydrocyclones are selected depending on the flow rate of wastewater, the concentration and properties of impurities contained in it. If a deeper purification of wastewater is required, sequential operation of hydrocyclones of various sizes is used.
To separate wastewater consisting of two or more phases, suspensions (liquid - solid), emulsions (liquid - liquid) and aerosols (gas - solid or gas - liquid), the centrifugation method is used. The process of separation of systems occurs under the action of centrifugal forces and allows you to get any degree of separation.
The degree of purification from suspended solids reaches 70-90%, and with the use of high-molecular electrolytes, the efficiency of centrifugation is 85-99%.
3. Filtering. When filtered, wastewater passes through a porous material that retains solids and does not retain liquid (filtrate).
Water filtration occurs under the action of a pressure difference at the inlet to the filter and at the outlet of it and can proceed at atmospheric pressure, at elevated pressure (pressure filtration) and under vacuum.
Physical and chemical cleaning methods. The main methods of physical and chemical treatment of industrial wastewater are neutralization, chemical precipitation, reduction, oxidation, coagulation, flotation.
- 1. Neutralization. The following neutralization methods are used:
- mutual neutralization of acidic and alkaline wastewater;
- neutralization with reagents (solutions of acids, quicklime, slaked lime, soda ash, caustic soda, ammonia);
- filtration through neutralizing materials (lime, limestone, dolomite, magnesite, burnt magnesite, chalk).
- 2. chemical precipitation. Chemical precipitation is reduced to the binding of ions into poorly soluble compounds. The choice of precipitant depends on the product of the solubility of the compounds formed (minimum value), the cost and availability of the reagent. The cheapest way is the transfer of heavy metal ions to the hydroxides of the corresponding metals by liming, usually a 5% solution of milk of lime is used. The use of sodium sulfide leads to the formation of more sparingly soluble compounds than hydroxides.
When the pH is exceeded above the optimum, the dissolution of hydroxides can occur, this is especially true for zinc hydroxides. With the successive use of sodium bicarbonate and sodium hydroxide, sparingly soluble compounds of zinc ZnC0 3 Zn (OH) 2 H 2 0 or copper Cu (0H) 2 C0 3 are formed.
3. Oxidation: chlorination, ozonation, hydrogen peroxide, photochemistry.
Chlorination. When introduced into water, chlorine hydrolyzes, forming hypochlorous and hydrochloric acid:
C1 2 + H 2 0NOS1 + HC1.
At a pH of more than 4, hypochlorous acid dissociates into a hypochlorite ion (OHG) and a hydrogen ion, the maximum amount of hypochlorite is formed in an alkaline environment at a pH of more than 9. For example, in an alkaline environment, hypochlorite oxidizes toxic cyanides (СЫ _) into cyanates (CNO -):
CNT + OSG -> CNO" + SG.
Chlorination is the main way to purify drinking water. Ozonation- the method is expensive, requiring a significant amount of electricity. It causes corrosion of metal, so the apparatus must be made of stainless steel and aluminum. Ozone and its water compounds destroy steel, cast iron, copper, rubber, ebonite.
However, ozone can destroy pollution that is not subject to biochemical oxidation. Ozone is effective in wastewater treatment from organic compounds, cyanides, hydrogen sulfide, sulfur compounds, oil products, manganese, hydrocarbons. The process is simple in hardware design, full automation of the process is possible, the oxidation products are non-toxic. The advantages of ozonation include: the formation of a small amount of sediment, the absence of the formation of additional impurities in the treated water, the production of the oxidizer on site, the possibility of full automation.
Oxidation with air, hydrogen peroxide. Technical oxygen, atmospheric oxygen and hydrogen peroxide can also be used to oxidize phenols, cyanides, thiocyanates, hydrogen sulfide and other impurities. In particular, for the oxidation of sulphide wastewater from cellulose, oil refineries and petrochemical plants, oxygen is used more widely than chlorine-containing reagents.
4. Coagulation. The presence of finely dispersed contaminants makes it difficult to separate the solid phase from the liquid, for example, during settling. The process of destabilization of finely dispersed systems with the use of salts of polyvalent metals and the formation of flakes is called coagulation. The coagulation process is accompanied by the sorption of pollutants on the surface of coagulant flakes, which have a minimum isokinetic potential.
The following types of coagulation are used.
Mutual coagulation of the sol by adjusting the neutralization mode. This method can be used to treat wastewater contaminated with metal ions with a high valence (> 3), which are capable of changing the magnitude and sign of the charge with a change in the pH value. Acid waste water is divided into two equal streams, one of which is neutralized to pH = 3.8-4.5 with the formation of positively charged metal hydroxides, the other to pH = 10-12 with the formation of negatively charged hydroxides. With the subsequent mixing of these streams, mutual coagulation of the sol occurs, and the rate of their deposition increases; neutral water is obtained with a pH of no more than 5. In this case, metal hydroxides with a valence below three are precipitated together. This method can be used to treat acidic mine waters contaminated with iron and aluminum ions.
Coagulation using reagents. The process of aggregation with the use of reagents - coagulants has found wide application for wastewater treatment.
The following reagents are used as coagulants:
- A1 2 (S0 4) 3 18Н 2 0 - aluminum sulfate;
- A1 2 (OH) 5 C1 6H 2 0 - aluminum oxychloride;
- NaA10 2 - sodium aluminate, is a white pieces, commercial product contains 55% A1 2 0 3 ;
- FeS0 4 2H 2 0 - iron sulfate II (iron sulfate);
- Fe 2 (S0 4) 3 2H 2 0 - iron sulfate III (iron sulfate);
- FeCl 3 - ferric chloride.
When aluminum and iron salts are introduced into water, as a result of the hydrolysis reaction, iron and aluminum hydroxides, which are slightly soluble in water, are formed.
Efficient coagulation requires the formation of insoluble, electrically minimally charged hydroxides and coagulant flakes, which, in turn, should form large solid flakes when coagulated in a free volume of water.
electrochemical coagulation. The aluminum or iron ions required for coagulation can be produced electrochemically. For this, non-pressure containers are used - electrolyzers (electrocoagulators), in which plate or cylindrical electrodes made of aluminum or steel are lowered. The electrolyzer is connected, as a rule, to a direct current network. In the process of anodic dissolution of the metal, A1 +3 or Fe +2 ions enter the water. Since ferrous ions are released with steel electrodes, it is oxidized with compressed air or chlorine to Fe +3.
It is advisable to use electrochemical production of coagulant at low flow rates of treated water.
5. Flotation. The method is based on the ability of hydrophobic particles to adhere to air bubbles and be carried into the foam product. Flotation separation of pollutants from wastewater can be a promising method due to the speed of the process - no more than 30 minutes. Apply pressure head, foam and column flotation (Fig. 3.3).
Rice. 3.3.
Foam separators are used to remove fine suspensions, fine impurities. Pressure flotation is used to remove oil products and suspended solids.
Without the use of reagents, the degree of purification does not exceed 20%; the use of reagents makes it possible to increase the degree of purification up to 93%. Natural suspended solids tend to have a negative charge, bubbles also carry a negative charge, so the likelihood of contact between suspended solids and a bubble is low. For example, for wastewater treatment from non-ferrous metal ions, the same set of collectors is used as collectors as for flotation of the corresponding type of ore. The use of water-soluble high-molecular polymers intensifies the flotation process. Coagulants are used.
The nature of the bubble saturation may vary depending on the design of the downcomer and the air supply system. The following schemes are distinguished: once-through, when all the purified water passes through the saturation system, and then enters the flotation machine; recirculation, when 20-50% of clarified water passes through the saturator; partially direct-flow, when 30-70% of the raw water passes through the saturator, and the rest is fed directly into the flotation cell.
Electroflotation. The electroflotation method is applicable for purification from non-ferrous metal ions in the form of hydroxides and basic carbonic salts, fine impurities, oils, oil products and surfactants. Electroflotation (electrochemical flotation) is a combination of two methods - electrocoagulation and foam flotation. The essence of the method lies in the fact that electrodes connected to a power source are placed in the purified water. On the anode (for example, graphite) and the cathode (nickel, iron, etc.), oxygen and hydrogen are released in the form of microbubbles, respectively. The flotationable or ready-to-float particles adhere to the bubbles and are carried into the froth bed (froth flotation). In the case of a soluble anode (eg iron, aluminium, copper, etc.) the metal ions will move towards the cathode; this phenomenon is accompanied by the formation of metal hydroxides, which are good coagulants.
It is advisable to use electroflotation for the treatment of wastewater containing a total concentration of metals not more than 200-300 mg/dm 3 , otherwise the concentration of sediments in the foam product is reduced. At higher concentrations, precipitation is used, and for post-treatment, electroflotation is used.
6. Sorption methods. Sorption is one of the effective methods of deep wastewater treatment. The efficiency of sorption is primarily due to the fact that sorbents are able to extract many inorganic and organic compounds from water, including biologically rigid ones that cannot be removed from it by other methods.
All finely dispersed substances with a developed surface can be used as sorbents - sawdust, ash, peat, clay, etc. The most commonly used synthetic ion exchange resins, carbons, activated inorganic materials.
The mechanism of sorption depends on the nature of the sorbent: activated carbons molecular (physical) sorption prevails, on ion exchangers - ion-exchange substitution reaction; on inorganic sorbents - molecular sorption and chemisorption. The sorption process can proceed in static and dynamic conditions. Sorption under static conditions is used if the sorbent is a finely dispersed substance.
Sorption on activated carbons makes it possible to achieve deep water purification up to MPC standards, which is especially effective for treating low-concentration wastewater and for extracting valuable components (gold, uranium, molybdenum, rhenium, etc.) from wastewater.
Typically, sorption on active carbons is used in combination with other methods, such as microbiological purification and ozonation.
Sorption on inorganic materials. For industrial treatment of large volumes of wastewater, quartz, talc, dolomite and limestone are most often used (flow rate 500-1000 mg / dm 3), slag from electric furnaces of metallurgical plants (flow rate 75-200 mg / dm 3). Clays, vermiculite, CHP ash and zeolites are also used.
Application of ion exchange technologies. Wastewater treatment using ion-exchange technologies is a promising but expensive method.
The use of ion exchange is limited by the degree of salinity of wastewater. Salt content should not exceed 2 g/l, the content of extractable ions in total should not exceed 1 g/l.
Sorption technologies are used to soften circulating water, desalination of waste and circulating water. The criterion for the use of sorption purification should be the ratio between the required depth of water purification and the cost of organizing purification, which includes the processing of eluates.
7. Biological methods. Biological methods are based on the ability of microorganisms to oxidize complex organic substances to end products - carbon dioxide and water.
Biological methods are widely used for wastewater treatment of various industries due to low energy consumption, high energy recovery potential (gas release during fermentation), the absence of secondary water pollution, the ability to provide strict discharge standards, and relatively low operating costs.
For biological treatment, wastewater must have a pH in the range of 6.5-8.5 and a temperature of at least 20 ° C, therefore, it is necessary to provide heating of bioreactors in the cold season in the climatic zone of Russia. The feasibility of using biological methods for the treatment of industrial wastewater can be judged by the BOD / COD ratio: this ratio should be at least 0.67 (for domestic wastewater, BOD p (pn / COD = = 0.86). The ratio is optimal for the treatment process BOD: N: P = 100: 5: 1. Accidental intake of heavy metals (copper, chromium VI, cadmium) even in small quantities (0.1 mg/l) can disrupt the activity of bacteria.Low concentrated wastewater - BOD 500 mg/l .
Biodegradable substances include cellulose, coal dust, lignin, tannin, sawdust, etc.
Microorganisms need proportional nutrition. The formula C |06 H 18() 0 45 N, 6 P characterizes the general chemical composition biomass cells. Industrial wastewater is often deficient in nitrogen and phosphorus.
Figure 3.4 shows the classification of the main apparatus for the implementation of biological cleaning methods.
Rice. 3. 4 .
Aerobic cleaning It is carried out by organisms that need free oxygen in the air, and occurs both in natural conditions (reservoirs, oxidation ponds, irrigation fields) and in artificial treatment facilities (in aerotanks of various systems, air filters, biofilters). Most often, aerobic treatment is carried out in aerotanks - open flow-type pools with forced aeration, containing activated sludge. There is a huge amount of bacteria and protozoa in the sludge. The sludge mixture (waste water and activated sludge) is subjected to intense aeration, the duration of which depends on the concentration of impurities in the waste water and the desired degree of purification.
The process is influenced by: the adequacy of the nutrient medium, temperature, toxic elements, the degree of aeration. The norm of dissolved oxygen is not less than 2 mg/l.
Factory ponds are a special case of aerobic treatment and are used for post-treatment at many metallurgical enterprises and concentrators. The disadvantage of this method of organizing biological treatment is the death of flora and fauna during salvo discharges of wastewater. The degree of purification lies in the range of 95-99%.
Anaerobic cleaning, i.e. cleaning without access to atmospheric oxygen takes place in menatens - closed-type tanks containing anaerobic sludge, which includes various groups of microorganisms that carry out fermentation processes. Complex organic compounds are converted into methane and carbon dioxide. The first bacterial community, consisting of acid-forming bacteria, converts complex organic compounds into simpler organic substances (acetic, propionic and butyric acids), which serve as a food source for the second community of methane-forming bacteria - they are the main organisms of anaerobic digestion, they are strict anaerobes and very sensitive to temperature and change in the pH of the medium: Eh 2 systems range from -0.2 to +0.3 volts.
Anaerobic treatment is carried out in the temperature range of 30-60 °C.
The advantages of the anaerobic method include: the possibility of treating very polluted wastewater without prior dilution and relatively low operating costs, since there is no need for air supply, and the moisture content of the sludge and its growth are many times less than in the aerobic process; in the process of fermentation, a significant amount of methane is formed, which can be used for energy needs.
Disadvantages of the process: low speed of the process, biological resistance of some organic compounds to decomposition, high sensitivity of anaerobic processes to temperature and concentration of substances, explosiveness of gases formed during fermentation).
Conclusion. Based on the above methods of wastewater treatment, the following layout technological solutions for the removal of pollutants can be recommended, depending on the type of wastewater before they are discharged into surface water bodies.
Industrial waste water.
Collector - wastewater equalizer => primary treatment facilities (settlers, flotation tanks) => reactor (mixers, flocculation chambers, separation devices) => post-treatment (sorption, filtration, membrane technologies => discharge.
Domestic waste water.
Screens => sand trap => primary settling tanks => bioreactor => secondary settling tanks => sludge dehydration unit => post-treatment unit => decontamination unit => outlet.
Surface wastewater.
Sand traps => settling tanks => release to surface sources.
In table. 3.2 shows the comparative cost of some cleaning methods.
Table 3.2
Comparative cost data for some cleaning methods
Thus, the protection of the hydrosphere is carried out by organizing effective schemes for the treatment of sources of wastewater generation and reducing the load on the natural mechanisms of self-purification of water bodies.