Requirements for reservoirs of fisheries. Rationing of water quality in water bodies and streams. background composition and water properties of the reservoir in places of wastewater discharge

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RULES OF PROTECTION OF SURFACE WATER (TYPICAL PROVISIONS) (approved by the State Committee on Nature of the USSR 21-02-91) (2017) Actual in 2017

2. Rationing of water quality in water bodies and streams

2.1. Rationing of water quality consists in establishing for the water of a water object a set of permissible values of indicators of its composition and properties, within which the health of the population, favorable conditions for water use and the ecological well-being of the water body are reliably ensured.

These Rules establish the standards for the quality of water in reservoirs and watercourses for the conditions of household, drinking, communal, domestic and fishery water use.

Note. As development and approval of environmental requirements and standards for the state of water bodies, as well as special requirements for the protection of waters used for agricultural purposes, these requirements will be taken into account, and the Rules will be supplemented by the relevant sections at the next revision.

2.1.1. The use of water bodies or their plots as a source of drinking water supply, as well as for water supply of food industry enterprises, is related to household water use.

To communal - domestic water use is the use of water bodies for swimming, sports and recreation of the population. The requirements for water quality established for municipal water use apply to all sections of water bodies located within the boundaries of populated areas, regardless of the type of use.

2.1.2. The use of water bodies for habitat, reproduction and migration of fish and other aquatic organisms refers to fisheries water use.

Fishery water bodies or their areas can fall into one of three categories:

the highest category includes locations of spawning grounds, mass feeding and wintering pits of especially valuable and valuable species of fish and other commercial aquatic organisms, as well as protected zones of farms of any type for artificial breeding and rearing of fish, other aquatic animals and plants;

2.1.3. The types of water use at a water body within the region (krai), union (autonomous) republic are determined by the State Committee together with the state sanitary inspection and subject to approval by the oblast (kray) executive committees of the Councils of People's Deputies or the Councils of the Union (autonomous) republics.

At the border between territorially - administrative units of water bodies, the type of water use is established by joint decision of the relevant authorities.

2.2. Water quality standards for water bodies include:

General requirements for the composition and properties of water in watercourses and reservoirs for various types of water use (Appendix 1);

The list of maximum permissible concentrations (MPC) of rationed substances in the water of water bodies used for drinking and household needs of the population (Appendix 2);

The list of maximum permissible concentrations (MPC) of standardized substances in the water of water bodies used for fisheries purposes (Appendix 3).

Notes. 1. The lists of maximum allowable concentrations should include: the full name of the substance and its synonyms (if they exist), a limiting sign of hazard, a hazard class, a standard numerical value with an indication of the unit of measure. In the absence of MAC for substances contained in wastewater of enterprises being designed or under construction, at the preventive control stage, the estimated allowable levels (TACs) of these substances in water are established, developed on the basis of calculated and express - experimental toxicity prediction methods.

2. Lists of rationed substances and their maximum allowable concentrations in the water of water bodies used for household, drinking and household needs of the population are approved by the Ministry of Health of the USSR, for fisheries purposes by the Ministry of Fishery of the USSR.

The lists of normalized substances and the values of their MPCs as they are developed and refined are issued as addenda to these Rules.

Methods for analyzing the content of substances in surface and return (waste) waters are developed by competent organizations, approved and recommended for use by the USSR State Committee for Nature Protection.

2.3. For all rationed substances for fishery water use and for substances belonging to hazard classes 1 and 2 for household and cultural water use, when several substances enter the water bodies with the same limiting sign of harmfulness and taking into account impurities entering the water body from of the upstream sources, the sum of the concentration ratios (C1, C2 ... Сn) of each of the substances in the control section to the corresponding MPCs should not exceed one:

С1 / ПДК1 + С2 / ПДК2 + ... + Сn / ПДКn<= 1.

2.4. When discharging return (waste) water or other types of economic activity affecting the state of water bodies used for drinking and household purposes, the water quality standards of water bodies and watercourses or its natural composition and properties should these be exceeded. in water courses at a site one kilometer above the point of water use nearest to it (water intake for drinking water supply, bathing, organized recreation, the territory of the settlement, etc.), and in reservoirs - in the waters within a radius of one kilometer from the point of water use.

When dumping return (waste) water or other types of economic activity affecting the state of the fishery watercourses and reservoirs, the water quality standards in water bodies or its natural composition and properties should these be exceeded within the entire fishery area, starting with the control of the site, determined in each case by the republican (oblast) Councils of People’s Deputies upon the submission of the State Committee bodies, but not more than 500 m from the place of discharge of waste water or provisions of other sources of impurities that affect the quality of water (places of mining, production work on water bodies, etc.).

Note. In reservoirs and in the downstream of a hydroelectric dam operating in a dramatically variable mode, it is necessary to take into account the possibility of an impact on the water use points of the reverse flow during an abrupt change in the mode of operation of the power plant or the cessation of its operation.

2.5. The water body or its site is considered polluted if the water quality standards in the water body are not complied with at the water use sites. In the case of simultaneous use of a water body or its site for various needs of the population and the national economy, the most stringent among the established ones are imposed on the composition and properties of water.

2.6. If in a water body, the maximum permissible concentration for individual substances is exceeded by MPC, then for these water bodies the USSR State Committee for Nature together with the USSR Ministry of Health and / or USSR Ministry of Fishery may establish regional water quality standards in accordance with natural background concentrations. Information on regional water quality standards is published as supplements to these Rules.

2.7. For unique water bodies of ecological, scientific, historical or cultural value, special requirements for water quality may be established. Such water bodies can be given the status of a reserve or reserve in the manner prescribed by law.

2.8. Separate watercourses, reservoirs or their areas can be provided for separate water use for use primarily for certain economic purposes, for example, for fish farming, cooling of heated water (cooling ponds), creating forest stock bases and other purposes.

Provision of a water body to separate water use is carried out in the manner prescribed by law.

Surface Water Protection

The value of water in the life of living organisms. Water reserves on the globe. The distribution of water resources. Uneven distribution.

Water consumption by industry, agriculture. For drinking purposes. Irrational costs.

Sources of water pollution. What are the properties of surface water change when discharging wastewater.

Composition and properties of wastewater.

Self-purification of water bodies. The role of physical and biological factors in this process.

The processes of mixing and dilution of wastewater in the reservoir. The mixing ratio and the dilution ratio.

Water quality standards for sanitary and domestic water bodies.

Rules of sewage in water bodies. Maximum allowable discharges (PDS).

Accounting for the harmful effects of a number of substances while their presence in the water bodies of water. Conditions for the safety of water.

Wastewater treatment methods.

The main measures for the protection of water bodies.

one . The value of water in the life of living organisms. Water reserves on the globe. The distribution of water resources. Uneven distribution. The importance of water in the processes of vital activity is determined by the fact that it is the main medium in the cell, where metabolic processes take place, it is the most important initial, intermediate or final product of biochemical reactions. The special role of water for terrestrial organisms (especially plants) is the need to constantly replenish it due to evaporation losses. Therefore, the entire evolution of terrestrial organisms went in the direction of adaptation to the active extraction and economical use of moisture. Finally, for many species of plants, animals, fungi and microorganisms, water is their immediate habitat. 97.2% of the water on Earth belongs to the salty oceans, seas and saline underground water bodies. The remaining 2.8% is freshwater. On Earth, it is distributed as follows: - 2.15% of fresh water is frozen in mountain glaciers, icebergs and ice shells of Antarctica and the Arctic; - 0.001% of fresh water is contained in the atmosphere; - 0.65% is contained where people can take it: in rivers, fresh lakes and springs.

2. Water consumption by industry, agriculture. For drinking purposes. Irrational costs. Agriculture accounts for more than 2/3 of the world's water consumption, approximately 17% of the acreage worldwide is irrigated. Now in the world under the acreage occupied about 15 million. quad km Water consumption by industry has now reached enormous proportions. According to expert estimates, the irretrievable water consumption was about 150 cubic meters. km per year, that is 1% of the steady flow of fresh water. According to calculations, the need for water on Earth until 2000 will increase on average by 3.1% per year. Currently, people annually consume 3,000 km of fresh water. One of the main consumers of water is irrigated agriculture - 190 m3 / year. To grow 1 ton of cotton, 4-5 thousand m3 of fresh water is required, 1 ton of rice - 8 thousand m3. With irrigation, most of the water is spent forever. Water consumption for irrigation depends on three factors: irrigation areas, crop composition and irrigation techniques. Municipal household water consumption exceeds 20 km3 / year. The level of development of municipal water supply is determined by two indicators: the provision of the population with a centralized water supply and the specific water consumption. An important task is to reduce the consumption of tap water for technical needs. Water consumption in industry is high (about 90 km3 / year). For smelting 1 t. Steel, 200-250 m3 of water is required, 1 t. Of cellulose - 1300 m3, ... There are large reserves of water saving in the industry due to the introduction of progressive technological processes. For example, in old petrochemical plants for processing 1t. oil consumes 18-22 m3 of water, while in modern plants with circulating water supply and air-cooling systems - about 0.12 m3 / year. At present, the situation is aggravated by the fact that after the privatization of the main number of enterprises, including environmentally polluted enterprises, the new owners do not have enough money to build or upgrade sewage treatment plants.

3. Sources of water pollution. What are the properties of surface water change when discharging wastewater.The main sources of pollution and littering of water bodies are insufficiently treated wastewater from industrial and municipal enterprises, large livestock breeding complexes, production wastes in the development of ore minerals; the waters of mines, mines, processing and fusing timber; discharges of water and rail transport; flax preprocessing waste, pesticides, etc. Pollutants, entering natural reservoirs, lead to qualitative changes in water, which are mainly manifested in changes in the physical properties of water, in particular, the appearance of unpleasant odors, tastes, etc.); in changing the chemical composition of water, in particular, the appearance of harmful substances in it, in the presence of floating substances on the surface of the water and putting them at the bottom of reservoirs. Sewage is divided into three groups: sewage, or faecal; household, including drains from the galley, showers, laundries, etc .; submersible, or oily. As a result

the discharge of sewage changes the physical properties of water (increases

temperature, transparency decreases, coloring, tastes appear,

smells); on the surface of the reservoir appear floating substances, and at the bottom

a precipitate is formed; changes the chemical composition of water (increases

substances, oxygen content decreases, active reaction changes

environment, etc.); changes in qualitative and quantitative bacterial

composition, pathogenic bacteria appear. Contaminated reservoirs become

unsuitable for drinking, and often for technical water supply;

lose fishery value, etc.

4. Composition and properties of wastewater.Many chemical production waste waters, in addition to dissolved organic and inorganic substances, may contain colloidal impurities, as well as suspended (coarse and fine) substances whose density may be greater or less than the density of water. In some cases, wastewater contains dissolved gases (hydrogen sulfide, etc.). Most often, wastewaters are complex systems containing mixtures of various substances.

The degree of harmfulness of wastewater depends on the toxicity of pollutants. Impurities such as heavy metal salts, hydrogen sulfide, carcinogens, and others cause high toxicity. Wastewater may contain flammable and explosive substances. The presence of a large number of suspended solids that can polymerize in aqueous solution can lead to clogging of pipelines and collectors. Often wastewater contains substances that have a strong unpleasant odor (sulfides, hydrogen sulfide). Many wastewaters from chemical plants are colored due to contamination with dyes and other colourants. The ingress of domestic water in the production leads to biological pollution of the latter. The temperature of wastewater can vary in different ranges.

5. Self-purification of water bodies. The role of physical and biological factors in this process.Self-purification is a complex set of physical, physico-chemical, chemical and biochemical phenomena. Hydrodynamic processes of mixing runoff with the water of a reservoir largely determine the intensity of self-purification, since they lower the concentration of pollution. Among the physical factors of self-purification are also the processes of deposition of insoluble impurities entering the reservoir with wastewater. Physical deposition phenomena are closely related to the vital activity of hydrobionts - filter feeders and sedimentators. They remove huge amounts of suspended solids from water and discard undigested material in the form of fecal clumps, easily settling to the bottom. Even more important is the formation of pseudo-faeces by mollusks. Thus, hydrobionts accelerate precipitation processes, helping to purify water from suspended solids and precipitate them into bottom sediments. Pure chemical reactions of neutralization, hydrolysis, and oxidation proceed in the reservoir. For example, during self-purification from Fe, Mg, Al ions, the predominant process is the formation of hydroxides of these metals with their subsequent precipitation. Self-purification from heavy metal ions occurs due to a number of processes: coprecipitation of the above-mentioned metals with hydroxides, sorption of ions with organic colloids, formation of complex organometallic complexes with humic acids. The share of each of these processes in the removal of heavy metals depends on the pH, redox conditions in the reservoir, the concentration of metals. As a result, water is freed from heavy metals, and in bottom sediments they accumulate. A change in redox conditions in bottom sediments can lead to the transition of metal ions into the aqueous layer, i.e. to secondary water pollution

6. The processes of mixing and dilution of wastewater in the reservoir. The mixing ratio and the dilution ratio.Dilution of sewage - is the process of reducing the concentration of impurities in water bodies, caused by the mixing of wastewater with the aqueous medium into which they are released. The intensity of the dilution process is quantitatively characterized by the dilution factor "A".

For reservoirs with directional flow, the dilution ratio is determined by the formula:

m = (mQ in + Q v) / Q v,

where Q v - volumetric flow of wastewater discharged into the reservoir with a volumetric flow of water Q in;

m is the mixing ratio, showing how much of the water flow in the reservoir is involved in mixing.

The mixing ratio is determined by the formula:

where k = - coefficient characterizing the hydraulic mixing conditions;

y - coefficient characterizing the location of the release of wastewater (for coastal release y = 1, for release into the channel section y = 1,5);

j = L / Ln - channel curvature coefficient;

L is the length of the channel from the release section to the design section;

Ln is the distance between the same parallel sections in the normal direction;

D T - coefficient of turbulent diffusion, determined by the Karaushev formula:

D T = gHw x / Mc w,

where g is the acceleration of gravity;

H - the average depth of the channel along the length of mixing;

w x - average over the course of the channel the flow rate of the river at a distance L from the place of discharge of wastewater;

With W - 40 ... 44 m 0,5 / s - coefficient Chezy;

M - function of the Chezy coefficient, for water M = 22.3 m 0.5 / s.

7. Water quality standards for sanitary and domestic water bodies.

2.1. The standards for the composition and properties of water bodies of water bodies, which must be ensured when using them for various economic purposes, are established for each category of water use.

The first category is the use of a water body as a source of centralized or non-centralized drinking water supply, as well as for water supply of food industry enterprises.

2.2. The first and second category water points that are closest to possible sources of pollution are determined by the bodies and institutions of the sanitary and epidemiological service with obligatory account of official data on the prospects for using a water body for drinking water supply and the cultural and everyday needs of the population.

2.3. The composition and properties of water bodies of water bodies must meet the requirements at a site located on watercourses one kilometer above the nearest points of water use (water intake for domestic water, bathing, organized recreation, the territory of the settlement, etc.). water bodies and reservoirs - one kilometer to both sides of the water use point.

2.4. The composition and properties of water in a reservoir or watercourse at drinking and cultural and community water use points should not exceed the standards given in applications number 1 and 2 . By SanPiN  4630-88

8. Rules of sewage in water bodies. Maximum allowable discharges (PDS). In accordance with GOST 17. 1. 01. 77 (p. 39), under the maximum permissible discharge (MPD) of substances into a water body, the mass of a substance in wastewater is accepted, the maximum allowable for diversion of a water body at a given time per unit of time in order to ensure regulatory water quality in the control point.

The PDS is established taking into account the maximum permissible concentrations of pollutants at water use sites and the assimilating capacity of the object. The values of the standards are determined in accordance with the water legislation of the Russian Federation and the current regulatory and procedural documents.

To develop a project Maximum permissible discharges (draft PDS)inventory of sources of discharges At this stage, methods for the discharge of wastewater from the territory, the presence of storm sewers and wastewater treatment plants, and the routes for disposal of domestic wastewater are determined. Water protection restrictions are identified in the area of the object under study (sanitary protection zone of drinking water supply sources, water protection zones of water bodies).

After artificial full or partial cleaning and disinfection of wastewater discharged into reservoirs. The water of the reservoirs contains a certain reserve of dissolved oxygen, which can contribute to the oxidation of organic matter in wastewater. These oxygen reserves, spent on biochemical oxidation of organic substances, are restored by absorbing it from the atmosphere by a water mirror (reaeration) and when carbon is absorbed by carbon from carbon dioxide. The smallest amounts of soluble oxygen in the water of reservoirs occur in the hot season, when the warm water loses oxygen, and in winter, in the absence of re-aeration due to ice cover of the reservoir mirror. Therefore, a powerful reservoir that has large amounts of water and oxygen reserves in it, has some self-cleaning ability.

Proper use of this ability of self-purification of water bodies for purification of organic pollution of wastewater makes it possible to reduce the degree of artificial wastewater treatment at sewage treatment plants before discharging into the water body and drastically reduce the cost of processing them without deteriorating the water quality of the water body.

Many enterprises lowered and some continue to discharge polluted wastewater without proper treatment, relying on the self-cleaning capacity (power) of the reservoir. As a result, the qualities of the natural properties of the water of many reservoirs have changed for the worse, and this has eliminated the possibility of their normal water use. In some cases, the descent of untreated wastewaters led to the poisoning of water in water bodies, clogging them with sludge deposits, oil products, dyes, which led to the death of fish.

In order to terminate the practice of water pollution, the Council of Ministers of the USSR by Resolution No. 425 of 22 / 1V-1960 “On Measures to Regulate the Use and Strengthening of the Protection of Water Resources of the USSR” prohibited the discharge of wastewater into water bodies without the consent of the State Sanitary Inspectorate.

In accordance with this Resolution, the Ministry of Health of the USSR No. 15 / VII-1961, under No. 372-61, introduced new elevated “Rules for the Protection of Surface Waters Against Pollution by Sewage Waters”. According to these rules, the extent and methods of wastewater treatment, and, consequently, the construction projects of the sewage system of enterprises and settlements should be coordinated with the republican authorities “Protection of surface and groundwater”.

9. Taking into account the harmful effects of a number of substances with their simultaneous presence in water bodies of water. Conditions for the safety of water. It is important to observe the principle of hygienic regulation with the simultaneous presence of several harmful substances in water. According to this principle, substances of a single PF exhibit an additive effect. This means that the total effect of two or several substances of one PF (each contained in the maximum permissible concentration) will be the same as if any of them, present in the water in the singular, were contained in two or more MACs. This provision in the Rules for the Protection of Surface Waters is fixed in the following form: when several substances with the same PFs enter the water body, the sum of the ratios of these concentrations of each of the substances in the calculated range to the corresponding MACs should not exceed unity, i.e.

The above-listed composition and water properties of water bodies used for household, drinking, cultural and domestic water use must comply with regulatory requirements at the site located on watercourses one kilometer above the water use point nearby (water intake for household water, bathing, organized recreation, item, etc.). Water safety indicatorschemical composition determined by chemicals that can adversely affect human health, causing the development of various diseases. They are divided into chemicals of natural origin; substances that are added to water as reagents; chemicals that enter the water due to industrial, agricultural, or domestic pollution of water sources.

10. Methods of wastewater treatment.Wastewater treatment - wastewater treatment to destroy or remove harmful substances from them. The release of wastewater from pollution is a complex production. In it, as in any other production, there are raw materials (wastewater) and finished products (purified water)

Methods of wastewater treatment can be divided into mechanical, chemical, physico-chemical and biological, and when they are used together, the method of treatment and neutralization of wastewater is called combined. The application of a method in each case is determined by the nature of the pollution and the degree of harmfulness of impurities.

The essence of the mechanical method is that mechanical impurities are removed from sewage by sedimentation and filtration. Depending on the size, coarse particles are trapped by grids, screens, sand traps, septic tanks, manure traps of various designs, and surface contaminants - by oil traps, gas oil separators, septic tanks, etc. Mechanical cleaning allows for the separation of insoluble impurities from domestic waste water, and from industrial up to 95%, many of which are valuable impurities, are used in production.

The chemical method is that various chemical reagents are added to the wastewater, which react with the pollutants and precipitate them as insoluble precipitates. Chemical cleaning is achieved by reducing insoluble impurities up to 95% and soluble up to 25%.

In the physico-chemical treatment method, finely dispersed and dissolved inorganic impurities are removed from wastewater and organic and poorly oxidizable substances are destroyed, most often coagulation, oxidation, sorption, extraction, etc. are used from physico-chemical methods. Electrolysis is also widely used. It consists in the destruction of organic matter in wastewater and the extraction of metals, acids and other inorganic substances. Electrolytic cleaning is carried out in special structures - electrolyzers. Wastewater treatment using electrolysis is effective in lead and copper enterprises, paint and varnish and some other industries.

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Literature

Protection of the hydrosphere. Rationing of water quality in reservoirs

Water quality is a characteristic of the composition and properties of water, which determines its suitability for specific types of water use.

Water use is understood as the order, conditions and forms of use of water resources. Rationing of the water quality of reservoirs is carried out in accordance with the “Rules for the Protection of Waters” (1991), which establish water quality standards for reservoirs for the conditions: drinking water, household water and fishery water use.

The use of water bodies or their plots as sources of drinking water supply, as well as for water supply of food industry enterprises is referred to as drinking water use.

The use of water bodies for bathing, playing sports and recreation of the population is referred to municipal water use. The requirements for water quality established for household water use apply to all sections of water bodies located within the boundaries of populated areas, regardless of the type of use.

The use of water bodies for habitat, reproduction and migration of fish and other aquatic organisms refers to fisheries water use.

Fishery water bodies or their areas can fall into one of three categories:

the highest category includes locations of spawning grounds, mass feeding of especially valuable and valuable species of fish and other commercial aquatic organisms, as well as protected areas of farms for their artificial breeding;

the first category includes water bodies used to preserve and reproduce valuable fish species that are highly sensitive to oxygen content;

the second category includes water bodies used for other fisheries purposes.

Quality standards for water bodies include:

general requirements for the composition and properties of water reservoirs for various types of water use, which include indicators such as: the presence of suspended solids, floating impurities, odor and taste, color, dissolved oxygen, pathogens, toxic substances, as well as water temperature, pH, water salinity, biochemical oxygen demand (BOD complete), (see Appendix G);

the list of maximum permissible concentrations (MPC) of standardized substances in the water of water bodies used for household, drinking and household needs of the population, which are approved by the Ministry of Health of the Russian Federation (see Appendix I);

the list of maximum permissible concentrations (MPC) of standardized substances in the water of water bodies used for fisheries purposes, which are approved by the Ministry of Fishery of the Russian Federation.

For water, maximum permissible concentrations of more than 960 chemical compounds have been established, which are grouped into three groups according to the following limiting hazard indicators (PEL): sanitary and toxicological (p. - t.); general sanitary (commonly); organoleptic (org.). The lists of maximum allowable concentrations should indicate the AP, hazard class, normative numerical value with indication of the unit of measure.

Under the organoleptic indicators are those that determine the appearance of water and are perceived by the senses (vision, smell). The description and definition of organoleptic properties is important for the sanitary characteristics of water: the presence of foreign odor and color indicates water pollution; muddy water is unpleasant in appearance and suspicious in bacterial terms; humic acids, which cause the color of water, can adversely affect mineral metabolism in the body, etc.

For all normalized substances in fisheries water use and for substances belonging to classes 1 and 2 of hazard for household and domestic water use, when several substances with the same AP come into the water bodies and taking into account impurities entering the water body from upstream sources , the condition must be met:

<=1, (4.1)

where C1, C2, C n is the concentration of each of the substances in the reference solution, mg / dm 3;

MPC1, MPC2 ,. MPC n - maximum permissible concentration of the same substances, mg / dm 3.

Note: Control target - cross section of flow, in which water quality is controlled.

For unique water bodies of ecological, scientific, historical or cultural value, special requirements for water quality may be established. Such water bodies can be given the status of a reserve or reserve in the manner prescribed by law.

The highest requirements are for drinking water. Sanitary standards for water used for drinking and in the food industry determine the organoleptic characteristics of water that are favorable for humans: taste, smell, color, transparency, as well as the harmlessness of its chemical composition and epidemiological safety. The same requirements apply to water from any source of water supply, regardless of how it is processed and the design of the water intake and water supply system. For drinking water, GOST 2874-82 establishes the following standards for organoleptic characteristics:

smell at 20 o С and at 60 o С no more than 2 points (weak, not attracting attention, but one that can be seen);

taste at 20 o С - no more than 2 points;

chromaticity - no more than 20 degrees; turbidity on a standard scale - not more than 1.5 mg / dm 3.

the presence of mineral impurities (mg / dm 3) should not exceed: chlorides (Cl -) - 350; sulfates (SO 2 - 4) - 500; iron (Fe 3+ + Fe 2+) - 0, 3; manganese (Mn 2+) - 0.1; copper (Cu 2+) - 1.0; dry residue-1000;

medium reaction pH 6, 5 - 8, 5.

Thus, water is suitable for drinking, if its mineralization does not exceed 1000 mg / dm 3. The very low mineralization of water (below 100 mg / dm 3) also impairs its taste, and the water, which is completely devoid of salts (distilled), is harmful to health, since its use disrupts digestion and the activity of the endocrine glands. The question of the quality of drinking water is solved by determining the number of E. coli in 1 dm 3 of water. E. coli is a microbe that constantly lives in the intestines of humans and animals and, therefore, is harmless. However, its presence in water indicates the presence of secretions of people or animals in it and the possibility of contamination of water with pathogenic bacteria. According to GOST, 1 dm 3 of drinking water may contain no more than three bacteria of the group of intestinal sticks (BGKP). This number is called the number index.

The general sanitary indicators of water bodies of water include: suspended solids (coarse impurities), dry residue, pH (pH), hardness, calcium, magnesium, chlorides, sulfates, ammonium salts, nitrates, nitrites, dissolved oxygen, hydrogen sulfide and some other inorganic and organic matter.

Hazardous substances with sanitary toxicological PPV include inorganic substances: beryllium, arsenic, mercury, rhodanides, selenium, cyanides, lead, molybdenum, fluorides and others, organic substances: benzene, benzo (a) pyrene, aniline, DDT, formaldehyde , methanol, polyacrylamide and others.

General requirements for the composition and properties of water of water bodies used for drinking and cultural and domestic purposes are given in Appendix G, and the MPC of some harmful substances in the aquatic environment in Appendix I.

Protection of water bodies in the discharge of wastewater

Classificationwastewaterwaters

In accordance with the “Rules for the Protection of Water”, water that is organized and returned by technical facilities and equipment from the economic component of the water cycle to natural units (oceans, lakes, rivers, lithosphere) is called return water - this is the generalized name of wastewater discharged into the water body, drainage water.

Waste water is a type of return water; includes household wastewater of populated areas, rainwater (snow) wastewater flowing from built-up areas, industrial wastewater.

Waste water - irrigation and irrigation water discharged respectively from irrigated farmland and built-up areas; a kind of return water.

Drainage water is groundwater discharged from irrigated and drained land tracts.

When dumping return (waste) water into reservoirs, the standard water quality in the control sections should not be disturbed.

In accordance with the "Rules for the Protection of Waters" it is prohibited to dump into water bodies:

return (waste) water containing substances for which no maximum allowable concentration (MPC) or TAC (estimated allowable levels) are established, as well as substances for which analytical control methods are not available, with the exception of those contained in the water of the reservoir;

return (waste) water, which, taking into account their properties and local conditions, can be directed to the circulating water supply systems, for reuse, for irrigation in agriculture while observing sanitary requirements or for other purposes;

industrial, domestic wastewater, rainwater and meltwater discharged from the territories of industrial sites and populated areas, not cleared to the established requirements;

wastewater that has a toxic effect on living organisms (according to the results of biotesting);

return (waste) water within the zones of sanitary protection of drinking water supply sources, to water bodies used for medicinal purposes, in spawning grounds, artificial breeding of fish and other aquatic organisms, to protected reservoirs;

return (waste) water containing causative agents of infectious diseases, as well as substances whose concentrations exceed the MPC and their background values in the reservoir, if they do not set the standards for maximum allowable discharge (MPD) specified in the permission to discharge return (waste) water;

the discharge into water bodies, on the surface of the ice cover and catchment, as well as in the sewage systems of sediments formed during the treatment of wastewater, including those containing radionuclides, technological and household waste is prohibited;

leaks into water bodies from oil and product pipelines, oil fields, as well as dumping of waste, untreated sewage, ballast water, as well as dumping of other substances from floating water craft are not allowed;

it is not allowed to wash vehicles in the reservoir and on their banks, as well as to carry out any work that may be a source of water pollution.

The discharge of return water (wastewater) into water bodies is one of the types of special water use and is carried out on the basis of permits issued in the prescribed manner by the State Committee on Ecology in coordination with the authorities of the State Sanitary and Epidemiological Supervision and taking into account the requirements of the fisheries. The conditions for diverting return (waste) water into water bodies are determined taking into account:

the degree of mixing of return (waste) water with water of a water body at a distance from the place of their release to the nearest control station for water use;

background composition and water properties of the reservoir in the field of wastewater.

Based on the calculation, the maximum permissible discharges (MPD) of substances are established for each wastewater discharge, compliance with which should ensure the standard water quality in the control points of the reservoir or the non-deterioration of the composition and properties of water under the influence of natural factors that are worse than the standard.

The PDS is set for each controlled indicator, taking into account the background concentration, water use category, water quality standards in the reservoir, its assimilative capacity and optimal distribution among water users of the mass of substances discharged with wastewater. It is advisable to calculate the MPD simultaneously for all water users of the river basin with consideration of the mutual influence of wastewater discharges.

Notes Assimilating ability of a water body - the ability of a water body to take a certain mass of substances per unit of time without violating the water quality standards in the water use control chamber;

Background concentration - the concentration of a substance in water, calculated for a given source of impurities in the background of a water body under calculated hydrological conditions, taking into account the influence of all sources of impurities except this source;

Background target is a cross section of flow, in which the background concentration of substances in water is determined.

The place of discharge of the sewage of the settlement should be located below its boundary along the river at a distance that excludes the influence of surges and surges.

Types of pollution and control of wastewater composition

Wastewater is a complex heterogeneous system polluted with substances that can be in all states - dissolved, colloidal and undissolved. Colloidal and undissolved substances form coarse - and finely dispersed suspensions, emulsions, foam.

Both organic and inorganic pollution components are always present in wastewater.

Organic substances in household wastewater are in the form of proteins, carbohydrates, fats, products of physiological processing. In addition, household wastewater contains large impurities - rags, paper, organic waste, as well as synthetic surfactants. Of the inorganic components in this category, effluent is always present in the form of potassium, sodium, calcium, magnesium, chlorine, carbonates, sulfates. Thus, the presence of all the main nutrients in them is typical for domestic wastewaters: C, N, P, S, K.

Household wastewater, in addition, necessarily contain biological contaminants, which are represented by bacteria, mainly isolated from the human intestine, helminth eggs, yeast and mold fungi, small algae, viruses, and therefore, these drains pose a significant epidemiological hazard to human, animal, plant, and also for natural communities in general.

The composition of industrial wastewater is very diverse and individual, depending on the type of product, type of process equipment, raw materials and materials used and many other factors.

In the water of domestic and industrial water supply, color, odor, transparency, acidity, alkalinity, dry residue, pH, nitrogen content, oxidability, biochemical oxygen demand (BOD), dissolved oxygen, chlorides, free chlorine (in the case of disinfection of waste water) are normalized. chlorine), phosphates, fluorides, iron, nitrates, nitrites, hardness and other components. All of these components are controlled in industrial wastewater. However, they also determine specific components characteristic of specific samples, related to the characteristics of production, for example, in petrochemical wastewater, most engineering and metallurgical industries determine the content of petroleum products; in the effluent of production using electrolysis and galvanization - the content of metals, cyanides.

To characterize the composition of wastewater used a large number of different types of analyzes - chemical, physico-chemical, sanitary-bacteriological, as well as the determination of the organoleptic properties of water using the senses of the researcher.

Difficulties in determining specific impurities in the wastewater of various industries are due to the inconstancy of the composition of the effluent, low concentrations of the components, the simultaneous presence of many different types of substances that interfere with and impede the selective determination. To solve this complex problem, modern physicochemical research methods are widely used - photocolorimetry, spectrophotometry, spectral, chromatographic and polarographic analysis methods.

Systematic analysis of the composition of wastewater discharged by industrial enterprises and utilities, is needed to verify the effectiveness of wastewater treatment plants, assess the impact of discharged wastewater on reservoirs, develop measures to improve the treatment facilities and to implement additional measures for the protection of reservoirs.

Cleaning of drains

The methods used for wastewater treatment can be divided into three groups:

1. Mechanical;

2. Physico-chemical;

3. Biological.

Disinfection (disinfection) is used to eliminate bacterial contamination of wastewater.

Domestic Wastewater Treatment

Through the numerous underground arteries, domestic and municipal wastewater flows day and night.

Domestic (faecal) wastewater includes drains entering the sewage system from kitchens and toilet rooms, baths, laundries, after washing floors, and also from household premises of industrial enterprises.

The methods of domestic wastewater treatment are divided into mechanical and biological.

A complex multi-stage path of purification and regeneration of water at a sewage treatment plant begins with a receiving chamber, then various mechanical structures filter it, freeing it from dirt, debris and harmful impurities. During mechanical sewage treatment, their liquid and solid phases are separated. For this purpose, gratings, gratings, crushers, sand traps, various septic tanks, etc. are used. Mechanical cleaning serves as a preliminary stage before biological cleaning, since, cleaning the water, all these grids, sand traps and other mechanisms cannot revive it. This water is dead, it has no salts, no microorganisms, or other necessary components.

Water is returned to life by microorganisms that are familiar to us from a school textbook of zoology - ciliates, shoes, rotifers, etc., the so-called “activated sludge”, which contains all these microorganisms and which is the main mechanism of biological treatment of the liquid part of wastewater. oxidation or reduction of organic substances in the waste water in the form of thin suspensions, colloids and in solution, and which are a source of food for microorganisms, results and the wastewater is treated by organic impurities.

Biological treatment facilities can be divided into two types:

Structures in which the purification takes place in conditions close to natural (natural biological purification);

Structures in which the purification takes place in artificially created conditions (artificial biological purification).

Natural biological wastewater treatment is carried out in the filtration fields, irrigation fields, in biological ponds, etc., (see Figure D.4).

Special facilities are used for artificial biological treatment: aerotanks, biofilters, and aero filters. In these structures, purification proceeds more intensively than in the irrigation fields, filtration fields, and ponds, because artificially, the best conditions are created for the active life of microorganisms.

Biological filters are structures in which wastewater is filtered through a feed material coated with a biological film formed by colonies of microorganisms. Gravel, expanded clay, slag, coarse sand, crushed stone, as well as gratings, rings, and packages made of polymeric materials are used as a loading material. Flowing through the loading of the biofilter, the wastewater leaves on it undissolved impurities that have not settled in the primary sedimentation tanks, as well as colloidal and dissolved organic substances, which are sorbed by the biological film. Biofilm has the appearance of mucous fouling with a thickness of 1 - 3 mm or more. Its color changes with changes in the composition of wastewater from grayish-yellow to dark brown. The microorganisms densely populating the biofilm oxidize organic matter, and from there they draw energy for their vital activity. Some organic substances are used by microorganisms to increase their biomass. Thus, organic matter is removed from the wastewater and, at the same time, the mass of the active biological film in the body of the biofilter increases. The spent and dead film is washed off with flowing waste water and removed from the body of the biofilter. The necessary oxygen for the biochemical process enters the strata of the charge by natural and artificial ventilation of the filter.

Aerotanks are long reinforced concrete tanks of rectangular cross section, in which a mixture of activated sludge and waste water is slowly moving. For the normal life of microorganisms in the aeration tank continuously enters the air, which is not only a source of oxygen, but also maintains activated sludge in suspension. The water here is black from silt flakes, rapidly "boils" saturated with oxygen from the blower station. It seems even dirtier and blacker than it was in the receiving chamber, but it is here, in the aeration tanks, that a revival metamorphosis occurs. Visible only in the microscope creatures, for the life of which oxygen is needed, decompose harmful impurities, eat up everything that could not be removed from the water during mechanical cleaning.

After aeration tanks or biofilters, the wastewater purified from organic impurities goes to secondary settling tanks, which serve to retain the activated sludge or biological film that comes along with the drains.

In the secondary sedimentation tanks, sludge flakes easily settle, clean living water runs into the river, and the sludge is sent back to work.

The concentration of various substances in wastewater is constantly changing, which makes it difficult to acclimatize microorganisms. Some harmful substances activated sludge is not able to decompose at all, and they transit to the reservoir. And in the case of salvo discharge into the sewage system of a large amount of toxic impurities, the microorganisms may even die, and the biological treatment station will fail for several months.

That is why, in order not to ruin the biological treatment, not to create emergency situations in the work of the city sewage system, special standards for the content of harmful substances in wastewater have been developed for industrial enterprises. Specific pollution should be collected at the local wastewater treatment plants of enterprises, and the city sewers should receive wastewater that meets the above standards.

Due to the fact that the wastewater of any settlement contains pathogenic microbes, they must be disinfected in all cases of using artificial biological treatment. In the practice of sewage treatment, disinfection (disinfection) is carried out by the same methods and means as in the treatment of natural waters. The most commonly used water chlorination or ozonation. Chlorination of waste liquid is carried out in special contact tanks arranged according to the type of horizontal and vertical clarifiers. The duration of the contact of chlorine with a liquid is at least 30 minutes. If the waste liquid contains at least 1.5 mg / dm3 of residual active chlorine, then it can be considered as decontaminated.

During sewage treatment, sediment is formed due to precipitation of undissolved substances in the primary sedimentation tanks. In addition, as a result of biological treatment, a large amount of sediment is formed, which is released in the secondary settling tanks. The precipitate consists of solids, strongly diluted with water. In the raw state during the treatment of domestic wastewater, this sediment has an unpleasant odor and is dangerous in terms of health, as it contains a huge number of bacteria, including disease causing bacteria. To reduce organic matter in the sediment and to give it the best sanitary indicators, the sediment is exposed to anaerobic microorganisms (fermentation) and aerobic stabilization of sludge in the corresponding structures. Anaerobic structures include bunk sedimentation tanks clarifiers - rotators, digesters. Aerobic stabilization can be carried out simultaneously for a mixture of sediment from the primary clarifier and excess activated sludge. The efficiency of the process is determined by its duration, temperature, intensity of aeration, and also depends on the composition and properties of the oxidized sludge. The stabilized sediment is subjected to coagulation, using iron, aluminum, ferric chloride, and lime sulphates as coagulants. This process of changing the structure of the sludge and improving its water withdrawal properties is called conditioning, which can also be carried out using heat treatment, freezing followed by thawing, and electrocoagulation. The moisture content of the conditioned sludge decreases from 92 - 94 to 70 - 75%, further dewatering of the sediments is carried out on sludge beds - plots of land on all sides.

water quality wastewater treatment

Dehydrated sewage sludge can be used as organic fertilizer if it does not contain heavy metals or other toxic substances.

The general scheme of a domestic wastewater treatment plant is shown in Figure D.5.

Industrial wastewater treatment

A significant proportion of the water reserves of industrialized countries is used for technical needs. The main direction in solving the problem of water reservoir protection is the maximum reduction of the amount of industrial wastewater, as well as the maximum reduction of waste, loss of raw materials and finished products discharged into the sewage system. Losses can be reduced by improving technological processes and regenerating valuable substances entering sewage.

The amount of wastewater discharged into the sewage system can be reduced by reusing the waste water in the same production operations where it was formed or using such water for other technological needs, where it is possible to use water of lower quality than the main water supply.

A significant reduction in water consumption is provided by the introduction of a circulating water supply system, when once taken from a reservoir water is no longer excluded from the system "water supply - sewage - treatment facilities - industrial water supply". Of course, there is a loss of water from a closed system due to evaporation, leaks in various parts of the system and extraction with sludge generated during sewage treatment, which are replenished by fresh water intake, but recycled water supply reduces fresh water consumption and prevents pollution of water bodies. At modern oil refineries and metallurgical plants, the water turnover has been increased to 97%.

Along with the circulating water systems of individual enterprises, industrial water systems are being created on the scale of industrial hubs and areas. Wastewater is treated at wastewater treatment plants, and then further processed at the city (district) treatment facilities and re-directed to consumers via technical water supply systems. At the same time, on the scale of an industrial hub, the task of introducing a waste-free, non-drainage technology is being solved, water withdrawal from reservoirs is sharply reduced, and the discharge of sewage completely stops there.

At industrial enterprises, as a rule, it is necessary to divert three main types of wastewater:

production, representing water, spent in the technological process of production or obtained in the extraction of minerals (for example, water from coal mines, mines, produced water from oil fields, etc.);

household - from sanitary facilities of administrative and industrial buildings, from washing floors in these buildings, as well as from shower installations located in production workshops;

atmospheric - rain and melting snow.

The amount, composition and concentration of industrial wastewater pollution depends on many factors: the type of raw materials being processed, the production process, the quality of water consumed for production purposes, waste water reuse systems and a number of other factors.

The type of processed raw materials has a significant impact on the composition of industrial waste; Often the constituent parts of the raw material are an integral component of the pollution of wastewater. For example, coal particles are the main pollutant of coal preparation plants; at oil refineries, such pollutants are oil and oil products; at the chemistry enterprises - acids, alkalis, etc. In addition, in the same industry in enterprises of the same profile, the amount of wastewater is not the same, and they have different concentrations of pollution. Therefore, for the treatment of industrial wastewater, depending on the composition of their pollution, various cleaning methods are used. They can be divided into destructive and regenerative.

Destructive methods of cleaning are reduced to the destruction of water polluting substances by their oxidation or reduction. The decay products formed in this process are removed from the water as precipitates or gases or remain in the form of soluble mineral salts. These methods are used for wastewater with organic impurities that do not represent technical value, or as an aftertreatment after regeneration methods. The main of destructive methods is the method of biological oxidation under aerobic or anaerobic conditions. Production waste cleaned by this method meets sanitary, hygienic and fishery standards and can be discharged into the reservoir or reused for technological needs.

Regenerative methods allow the extraction and disposal of valuable substances contained in water. Regenerative methods do not always purify water to a state in which it can be discharged into reservoirs. In these cases, water is purified after destructive methods.

In all cases of wastewater treatment, the first stage of this process is mechanical cleaning, designed to release water from suspended and colloidal particles. The next stage of purification is the removal of chemical compounds dissolved in it by physicochemical, chemical, electrochemical, and biological methods. In many cases, combinations of methods are used.

The most commonly used methods are:

to remove coarse particles - filtering, settling, flotation, clarification, centrifugation;

to remove fine and colloidal particles - coagulation, flocculation, electrical deposition methods;

for purification from inorganic compounds - distillation, ion exchange, reverse osmosis, chemical precipitation, cooling methods, electrical methods;

for purification from organic compounds - extraction, absorption, flotation, ion exchange, reagent methods, biological oxidation, liquid phase oxidation, ozonation, chlorination, electrochemical oxidation;

for cleaning from gases and vapors - blowing off, heating, reagent methods;

for the destruction of harmful substances - thermal decomposition.

Mechanical sewage treatment - (filtering, settling, filtration) is used to extract undissolved mineral and organic impurities from wastewater. The advantage of these processes is that they can be used at normal temperature and without the addition of chemical reagents. This treatment, as a rule, is a preliminary, less often - the final method of treatment of industrial wastewater.

The filtering method is used to remove suspended particles larger than 15-20 mm in size. For this purpose, a variety of grids, nets and sieves are used, which can be movable or fixed, often combined with crushers to grind contaminants.

After straining, the wastewater enters sand traps designed to separate smaller mineral impurities with relatively high density. When water moves in the sand trap tank, sediments with a grain diameter of more than 0.25 mm are deposited on its bottom. The sediment is transported with the help of scrapers into a special bunker, from where it is removed to a sandy ground for neutralization. Sand traps facilitate the working conditions of facilities for the further treatment of effluents (septic tanks, digesters, etc.) and are installed in circuits that allow at least 100 m 3 of wastewater per day.

The method of sedimentation is used to isolate smaller organic and mineral suspensions; various types of septic tanks are used for this purpose. Distinguish between septic tanks of periodic and continuous action. In the direction of water movement, they are divided into horizontal, vertical and radial. In addition, the septic tanks are primary, which are installed in front of the facilities for biological treatment of water, and secondary - they are used to clarify wastewater that has already passed biological treatment. The septic tanks can be used as independent wastewater treatment plants, if for sanitary conditions it is enough to separate only mechanical impurities from wastewater.

For the separation of oils, fats, resins, oil and oil products floating on the surface of wastewater, various designs of oil traps, grease traps, oil traps are used.

Oil traps are used to clean wastewater containing coarse-dispersed oil and oil products at a concentration of more than 100 mg / dm 3 in wastewater. They are rectangular, elongated in length tanks, in which the separation of these impurities from the water is due to the difference in their densities. Oil floats to the surface, it is collected using slotted pipes, and mineral impurities contained in the wastewater settle to the bottom of the oil trap. The water freed from the oil enters the discharge manifold and can be returned to production.

Grease trapping Fats and oils as well as oil products are not allowed to descend into water bodies, as they, covering with a thin film, large areas of water surface, impede the access of oxygen to air and thereby inhibit the self-purification processes of the reservoir. In addition, these contaminants separated from wastewater can be used for technical needs. Grease traps, like oil traps, can be installed directly at individual production plants, the wastewater of which contains a lot of fat or directly on the general stock of fat-containing water.

The method of filtering wastewater is used to extract finely dispersed substances from them that have not settled on settling (oils, resins, fibers, dust, etc.); when additional purification of wastewater after biological or other processing methods. After aeration tanks, filters are provided to trap fine particles of activated sludge, which absorbed organic contamination of wastewater on its surface. For filtering wastewater using filters with mesh elements and filters with a filtering granular layer. Metallic perforated sheets and nets of acid-resistant steel, aluminum, nickel, brass, etc., as well as various fabric partitions — asbestos, glass, cotton, wool, artificial fibers, and ceramic plates are used as mesh elements. Quartz sand, finely ground granite, coke breeze, peat, brown and black coal, etc. are used as a granular filtering layer. The filter material must have the required porosity, sufficient mechanical strength against abrasion and chemical resistance.

Chemical wastewater treatment is used in cases where the release of contaminants from wastewater is possible only as a result of chemical reactions between these contaminants and reagents introduced into the wastewater. When this occurs, the oxidation and reduction of impurities dissolved in water to obtain non-toxic or low-toxic products; conversion to water-insoluble compounds; neutralization of acids and alkalis. The most widely used such reagents: oxidizing agents - chlorine, potassium permanganate, ozone; alkalizing substances - lime, soda; acidulants - sulfuric and hydrochloric acids. All chemical cleaning methods require reagents and therefore expensive. Chemical treatment methods include neutralization, oxidation, ozonation, electrochemical oxidation, etc.

The oxidation of pollutants in wastewater is used in cases where these substances are impractical or cannot be removed or destroyed by other means, including through biochemical oxidation. Such substances include arsenic compounds, cyanide compounds that pollute the wastewater of many industries, for example, wastewater from enrichment plants of lead - zinc and copper ores, electroplated coating shops of engineering plants.

For sewage treatment from cyanic compounds, cyanide (CN -) is oxidized to harmless cyanate (CNO -) or toxic compounds are transferred to a non-toxic complex or precipitate (in the form of insoluble cyanides), removed from the wastewater by settling or filtration.

The oxidation of cyanides to low-toxic cyanates can be carried out by a relatively inexpensive oxidizing agent — hypochlorite in an alkaline medium at pH = 10.11. As a reagent containing hypochlorite - ion (O Cl -), bleach, calcium hypochloride or sodium hypochloride serves.

The chlorination process is carried out in periodic or continuous chlorinators, pressure or vacuum (Figure I.2). In these plants, wastewater is purified from hydrogen sulfide, hydrosulfides, methyl-sulfur compounds, phenols, cyanides.

Ozone (O 3) is a very promising oxidizer for wastewater. Ozonation not only cleans the effluent from phenols, petroleum products, hydrogen sulfide, arsenic compounds, surfactants, cyanides, carcinogenic aromatic hydrocarbons, pesticides and many other toxic impurities, but also simultaneously deactivates and disinfects water and eliminates odors and flavors. When treating water with ozone, pathogenic microorganisms die several thousand times faster than when it is treated by chlorination. In wastewater, ozone is served as an ozone-air or ozone-oxygen mixture, in which the ozone content usually does not exceed 3%. Ozonation of industrial wastewater is carried out in bubbling, packed, disc-shaped columns and other contact devices (Figure D.3).

The cleaning process can be accelerated by the combined use of ozone and ultrasonic treatment or ultraviolet irradiation of wastewater. Thus, ultraviolet irradiation accelerates the oxidation of impurities in industrial effluents by 10 2 - 10 4 times.

Recovery as a cleaning method is used when industrial effluents contain easily recoverable substances. These methods are often used to remove chromium, mercury and arsenic compounds from wastewater. Chromium (IV) contained in industrial effluents is reduced to Cr 3+, followed by its precipitation in an alkaline medium in the form of hydroxide (Cr (OH) 3.). As reducing agents, activated carbon, organic waste (for example, newsprint), ferrous sulfate (Fe SO 4), sodium hydrosulfite (Na HSO 3), sulfur dioxide (SO 2), hydrogen are used.

Mercury of inorganic compounds contained in wastewater is relatively easily reduced to metallic, which is then released by settling, filtering or flotation. Iron sulfide (Fe S), sodium hydrosulfite (Na HSO 3), powdered iron, aluminum powder, hydrogen sulfide are used as reducing agents in the capture of mercury. Organic mercury compounds are first destroyed with the help of strong oxidizing agents, and then its cations are reduced: Hg 2+ to Hg 0.

Neutralization of wastewater. Industrial wastewater from many industries contain acids and alkalis. The intensity of the acid or alkaline reaction is determined by the pH value. To prevent corrosion of sewage materials and disruption of biochemical processes occurring in sewage treatment plants and reservoirs, such waters are neutralized. Neutralization is often also carried out to precipitate heavy metal salts from wastewater.

In all cases, the possibility of mutual neutralization of acids and alkalis discharged with wastewater is taken into account. Almost neutral is considered to be a mixture with a pH value in the range of 6, 5 - 8, 5, therefore, wastewater, the pH of which is below 6.5 or above 8, 5, should be neutralized before descending into the pond.

The neutralization process is carried out in flow or contact type neutralizers, which can be constructively combined with settling tanks. Under favorable local conditions, the clarification of neutralized wastewater can be carried out in sludge tanks in the open air. To neutralize acidic wastewater, any alkaline reagent is used, which gives OH - ions in solution; most commonly used caustic, carbonic and bicarbonic alkali. The cheapest reagents are Ca (OH) 2 (in the form of fluff or milk of lime), as well as carbonates of calcium or magnesium (in the form of crushed chalk, limestone and dolomite). Sodium hydroxide and soda are used only in the case when these reagents are local waste.

When neutralizing, for example, hydrochloric acid wastewater from pickling shops with lime milk, the following reactions take place:

4 H Cl + Ca (OH) 2 + Ca CO 3 2 Ca Cl 2 + CO 2 + 3 H 2 O 2 Fe Cl 2 + Ca (OH) 2 + Ca CO 3 Fe (OH) 2 + Fe CO 3 + 2 Ca Cl 2

As a result of neutralization, only iron in the form of nitrous oxide or carbonate is precipitated. The remaining neutralization products remain in solution, increasing the salinity of the neutralized effluent. A schematic diagram of the neutralization plant is shown in Figure 4.1. The main facilities include: tanks - averagers for acid and alkaline wastewaters 1; reaction chambers - neutralizers 6; sumps for neutralized wastewater or accumulators 7, which are both sumps and capacity for sludge; sludge dewatering facilities 8; reagent farm (dispensers 5; mortar tanks 4, lime slavers 2, quick lime warehouse 3).

The use of quicklime for neutralization is provided in the form of milk of lime at 5% concentration of active calcium oxide. Dosing of lime is carried out by an automatic dosing unit, depending on the flow rate or pH value of the treated wastewater. The clarified water after the sedimentation tanks can be used in circulating water supply systems. The sediments (sludge) released in the settling basins are dehydrated at sludge plots - sludge collectors.

Physico - chemical methods of wastewater treatment are used to purify industrial wastewater from finely dispersed suspensions that are not captured by filtration, soluble gases, inorganic and organic compounds. These methods are based on the use of a number of processes: coagulation, sorption, extraction, flotation, crystallization, dialysis, decontamination, desalination, etc., and allow you to remove toxic, biochemically non-oxidizable organic compounds from wastewater and achieve a deep and stable level of purification. Physico-chemical methods allow you to fully automate the cleaning process, and the current level of knowledge in the field of the kinetics of many physical-chemical processes provides the basis for their mathematical modeling and optimization, which allows you to correctly select and calculate the parameters of the equipment. In most cases, the use of physicochemical methods for the release of pollutants from wastewater allows them to be further recovered.

Coagulation is the process of enlarging dispersed particles and combining them into aggregates under the influence of chemical and physical processes that occur spontaneously in solution, or under the influence of special substances coagulants introduced into the solution. Salt of iron, aluminum, silicic acid, polyacrylamide are used as coagulants in wastewater treatment. In addition, substances that have high adsorption properties are used to coagulate wastewater impurities: clay, ash and slag, activated carbon, etc. The coagulation method is widely used to clean wastewater from textile enterprises, artificial fiber mills, oil refineries and chemical plants.

The process of aggregation of suspended particles when high-molecular compounds are added to wastewater is called flocculation. Flocculation is carried out to intensify the process of formation of flakes of hydroxides of iron and aluminum and increase the rate of their deposition. The use of flocculants allows to reduce the dose of coagulants while accelerating the process of clarification of wastewater.

Extraction is the process of separating dissolved organic impurities, for example, phenols, fatty acids, oils found in wastewater, by treating the latter with some solvent that is not miscible with water - an extractant, in which impurities that contaminate water dissolve better than in water. . For example, the amount of dissolved phenol in butyl acetate is 12 times more than in water. As extractants for wastewater treatment use organic solvents that are insoluble in water: benzene and some of its derivatives, carbon disulfide, carbon tetrachloride, mineral oils. A good estrogen must satisfy several requirements:

dissolve the extracted substance is much better than water, i.e. have a high distribution coefficient;

have good selectivity (selectivity) in relation to the extracted impurities;

have low solubility in waste water and not form stable emulsions with it;

significantly different from the waste water in density, since a significant difference in density provides a quick and complete separation of the phases;

regenerated in a simple and cheap way;

do not interact with the extracted substance, as this may impede the regeneration of the extractant and increase its loss;

if possible, not be toxic, explosive and do not cause corrosion of the material of the apparatus.

The feasibility of using extraction for wastewater treatment is determined by the value of the extracted substances and their concentration. For each substance, there is a "concentration limit" of the profitability of its extraction. The process is considered economically viable if the cost of the extracted substances compensates for all the costs of its implementation. It is usually considered that at a concentration above 3–4 g / dm 3 it is advisable to remove the impurities by extraction.

Flotation - the release of impurities from wastewater by giving them buoyancy at the expense of flotation reagent, enveloping particles of impurities and removed from the water with it. In flotation treatment, the saturation of waste water with bubbles of finely dispersed air is used. Particles contained in wastewater (emulsified oil, pulp and paper fiber, wool, etc.), stick to air bubbles and float with them to the surface of the water, and then removed from the water. To enhance the flotation effect, surfactants are added to the water (surfactants), which lower the surface tension of the liquid and weaken the bond of water with the flotation substance, as well as blowing agents that increase the dispersion of air bubbles and their stability. Flotation processes proceed continuously, have a high selectivity of the selection of impurities at a high speed of the process, do not require complex and expensive equipment, the degree of purification reaches 95 - 98%.

Sorption is used to extract organic substances and gases (phenols, pesticides, aromatic nitro compounds, surfactants, dyes, etc.) dissolved in wastewater by concentrating them on a solid surface (adsorption) or by absorbing a substance from a solution or mixture of gases by liquids (absorption), or by chemical interaction of solutes with a solid (chemisorption).

The efficiency of processes, such as adsorption, depends on the chemical nature of the adsorbent, the size of the adsorbing surface, as well as on the structure and properties of trapped impurities. As adsorbents, peat, sawdust, slags and other low-value substances are used, which are usually removed or burned after a single use. If the pollutant or adsorbent is of a certain value, then the adsorbent is regenerated by removing the absorbed substance from it. The most effective, but also the most expensive sorbent used in water purification schemes, is activated carbon.

Ion-exchange purification is used to extract metals (zinc, copper, chromium, nickel, lead, mercury, cadmium, vanadium, manganese) from waste waters, as well as arsenic, phosphorus, cyanide compounds. This cleaning method allows not only to clean the wastewater from toxic elements, but also to capture a number of valuable chemical compounds for reuse. As ionites natural mineral compounds are used, such as zeolites, clay minerals, fluorapatite F 2, hydroxylapatite, organic compounds - humic acids of soils and coals; synthetic ion exchangers are also used: inorganic (silica gels and sparingly soluble oxides and hydroxides of aluminum, chromium, zirconium) and organic (mainly organic resins). The most widely used ion exchange resins are high-molecular compounds. In water, ion exchangers do not dissolve, but swell, and the size of their micropores increases from 0.5 to 1.0 nm to 4 nm, and the volume of the ion exchanger increases 1, 5 to 3 times. Swelling affects the selectivity of the ion exchanger, since, with a small pore size, large ions cannot reach the internal functional groups.

The process of ion-exchange sewage treatment is carried out on a periodic (Figure I.1) and continuous installations.

Industrial effluents that cannot be cleaned by the methods described above, or if these methods are not applicable by technical and economic indicators, are subject to evaporation, incineration or injection into deep absorbing layers.

Literature

1. Vernadsky V.I. Living Substance and Biosphere. - M .: Science, 1994. - 670 p.

2. Lozanovskaya I.N., Orlov D.S., Sadovnikova L.K. Ecology and protection of the biosphere during chemical pollution: Proc. p .: M: Higher. school., 1998. - 287 p.

3. Odum Y. Fundamentals of Ecology. M .: Mir, 1975. - 740 p.

4. Radkevich V.A. Ecology: Textbook. - M .: Higher. shk., 1997. - 159 p.

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Basic principles. Each state, in exercising the right to conduct the necessary policies for the national environmental system, must comply with

Protected areas as a form of environmental protection
In order to preserve the biological diversity of the state, there is a need for the further development of specially protected natural territories of the Republic of Kazakhstan (hereinafter referred to as PAs). According to

Protection of genetic diversity. Biosphere reserves. Red Book and its role in the conservation of biological diversity
Nature has constructed in the process of evolution an innumerable variety of life forms. One of the priority tasks of nature conservation is the preservation of this biological diversity. Under

The processes of destabilization of the natural environment of the Republic of Kazakhstan, causes and effects
Kazakhstan, as a participant in global processes and phenomena, also strives to achieve sustainable development and makes considerable efforts to this end: from identifying processes that destabilize the natural environment.

Methods and criteria for assessing the state of the environment
The criteria for assessing the state of the environment are divided into direct and indirect, particular and integral, or form a system of criteria. Direct criteria reflect direct impact.

Environmental monitoring, principles of its organization
Environmental monitoring is called regular, performed according to a given program of observation of natural environments, natural resources, flora and fauna, allowing

Legislation of the Republic of Kazakhstan in the field of environmental protection
Environmental law is a branch of law, the norms of which regulate social relations in the field of interaction between society and nature, that is, relations connected with the use and

The concept of maximum permissible emission
To assess the quality of atmospheric air and for the purpose of state regulation of emissions of harmful (polluting) substances into the atmospheric air, specific emission standards are established

Cyclone operating principle
Cyclones of various types are widely used for dry gas cleaning (Figure 3.1). The gas stream is introduced into the cyclone through the pipe 2 at a tangent to the inner surface

Radial dust collector
In radial dust collectors (Figure 3.4), the separation of solid particles from the gas flow occurs due to the combined action of gravitational and inertial forces. The latter arise

Rotary Dust Collector
Rotary dust collectors (Figure 3.2) relate to centrifugal devices and constitute a machine that simultaneously with the movement of air cleans it from

Wet dust and gas emissions cleaning methods
Wet dust collectors. Apparatuses for wet gas cleaning are widespread, as they are characterized by high cleaning efficiency from fine dusts with a diameter of

Venturi scrubber principle of operation
Among the wet cleaning machines with the deposition of dust on the surface of the droplets, Venturi scrubbers have found the greatest practical application (Figure 3.8). The main part of the scrubber - Be nozzle

Spray nozzle
A variety of dust collection devices for particle deposition on liquid droplets are spray scrubbers (Figure 3.9a). The dusty gas stream enters the scrubber on the

The principle of action of the bubble-foam dust collector
Wet dust collectors include bubble-foam dust collectors with failed and overflow gratings (Figure 3.10). In such devices, the gas for cleaning enters the grid 3, passing

There are several types of water pollution: - microbial - intake of pathogenic microorganisms into water bodies; - heat - heat input to the water bodies

The principle of the sump
Sumps are vertical, radial and horizontal. The vertical sump is a cylindrical or square tank with a conical bottom. Sewage is supplied through the central

The principle of the clarifier
Figure 3.15 shows a schematic diagram of the clarifier. Water with a coagulant is fed to the lower part of the clarifier. Coagulant flakes and suspended particulates enthralling them rise the sunrise

The principle of the filters
Filtration is used to extract finely dispersed impurities from the wastewater, the removal of which by settling is difficult. The separation is carried out using porous partitions, p

Wastewater treatment by coagulation
Coagulation is the process of enlarging dispersed particles as a result of their interaction and aggregation into aggregates. This method is used to accelerate the process of precipitation of thin-film

Biological cleaning methods
Biological methods are used to clean household and industrial wastewater from a variety of dissolved organic and some inorganic (hydrogen sulfide, ammonia, etc.) connected

Aerobic methods of sewage treatment. Aerotank action principle, filtration fields and irrigation fields.
The aerobic method is based on the use of aerobic microorganisms, which require a constant flow of oxygen and a temperature in the range of 20 ... 40 0

Anaerobic methods of sewage treatment. Principle of action of the digester
Anaerobic cleaning method proceeds without air access. It is mainly used for the neutralization of solid precipitates, which are formed during mechanical, physico-chemical

The concept of soil and soil-forming factors
Underground resources understand the land systematically used or usable for specific economic purposes. Of particular importance to humans is

Soil erosion
One of the types of negative impact on the soil is its erosion. Under soil erosion, the diverse processes of destruction and removal of soil by water flows and

Soil desertification
Desertification is a process that leads to the loss of the natural ecosystem of a continuous vegetation cover with the further impossibility of its restoration without human participation. Origin

Water logging
Waterlogging is a hydrogenic succession of natural landscapes as a result of natural and anthropogenic factors. Occurs due to the rise of ground and surface waters, abundant in

Soil salinization
Soil salinization is also due to natural (primary salinization) and anthropogenic (secondary salinization) factors. It may be due to soil salinity, etc.

Methods and means of protection from noise
Noise is a random mix of sounds of varying frequency and intensity. Sound is an oscillatory motion of particles of an elastic medium, propagating in

Methods of protection against non-ionizing electromagnetic radiation
Sources of electromagnetic radiation are natural artificial. By natural is the magnetic field of the Earth. It is characterized by intense