Pollution from domestic wastewater. Types of wastewater pollution: methods of their treatment

Stationary sources of pollution generate surface runoff, including rainwater and melted snow water, water from washing rolling stock and cleaning premises, and wastewater generated in production processes.

Industrial wastewater occurs in many technological processes. The composition and quantity of these waters are different. Wastewater is generated during the washing of rolling stock, cleaning of components and parts in washing machines, during the repair of batteries, galvanic and mechanical processing of parts, hydraulic testing of various containers, etc.

Surface runoff from the territories of transport enterprises contains liquid petroleum products, residues of detergents, disinfectants, anti-icing and de-icing reagents, molding sands, solutions used in metalworking, waste battery electrolytes, products of destruction of artificial surfaces and tire wear. The wastewater contains liquid toxic substances - benzene, acetone, acids, alkalis, dissolved metals (aluminum, beryllium, chromium, etc.), and petroleum products.

Benzene C D) H 6 - colorless liquid, used as a solvent, for example, oil paints, fats. Has an acute local irritant effect. In addition, it is absorbed by the skin and causes a general toxic effect on the body. In water bodies contaminated with benzene, fish acquire an unpleasant odor at a concentration of 10 mg/l.

Acetone CH 3 SOCH 3 is an easily evaporating, colorless liquid, and is a solvent for nitrocellulose paints and varnishes. Low toxic substance. It has only a local irritant effect on the skin and mucous membranes. It has virtually no impact on the sanitary regime of the reservoirs into which the discharge occurs.

Acids And alkalis, entering water bodies with surface runoff, change their acidity and thereby affect the living conditions of aquatic organisms, the composition and size of populations. Thus, alkaline waters with pH > 9.5 pose an immediate danger to fish, alkaline waters with pH = 8.6-9.5 have a depressing effect on fish after a long time, acidified waters with pH = 6.4-5.0 dangerous for fish if there are simultaneous presence of iron salts in the reservoir.

Highly toxic metals ( lead, arsenic, cadmium, mercury), contained in industrial wastewater can enter the human body with drinking water, which will lead to poisoning. Some rare metals (molybdenum, gallium, germanium) less dangerous, but enhance the effect of other pollutants on the body.

Metals such as lead, zinc, copper, chromium, and arsenic are not excreted from the body and increase their toxic effects as they accumulate. These metals also accumulate in soil and plants when they are exposed to surface runoff.

Industrial wastewater from transport organizations, especially factories, often contains compounds aluminum, beryllium, chromium and other non-ferrous metals. Beryllium and chromium compounds are highly toxic. Aluminum compounds that are insoluble in water are considered non-toxic. Soluble aluminum salts (chlorides, sulfates, nitrates), when they enter living organisms with drinking water, have a toxic effect. They accumulate in body tissues. Aluminum compounds delay the self-purification processes of water bodies.

Another negative impact of metals in surface runoff is the corrosion of metal sewer pipes, which causes very large economic damage.

Petroleum products when released into water bodies with wastewater, they cause profound changes in the composition of aquatic biocenoses. Petroleum products penetrate into all layers of the reservoir - one part of their components settles to the bottom, the other is in the form of suspensions and emulsions in the water column, and the rest are in a molecularly dissolved state, therefore all aquatic organisms, no matter where they live, experience negative effects impact. Aquatic plants covered with an oil film are not suitable for fish spawning. The fish itself in water containing petroleum products in quantities greater than 0.1 mg/l acquires the smell of oil after 1-3 days. stay in it. A surface oil film saturates the feathers of birds landing or diving into the water; they cannot take off and die.

All toxic pollutants from mobile and stationary sources are divided into four classes according to the degree of danger:

1 - extremely dangerous (tetraethyl lead, lead, mercury, etc.);
2 - highly hazardous (manganese, copper, sulfuric acid, chlorine, etc.);
3 - moderately dangerous (xylene, methyl alcohol, etc.);
4 - low-hazard (ammonia, gasoline, kerosene, carbon monoxide, turpentine, acetone, etc.).

One of the sources of pollution of natural water bodies is wastewater. This is the name given to any water, including that which falls in the form of precipitation, which is removed from the territory of populated areas and industrial enterprises through sewerage outlets. Most large settlements are equipped with centralized systems for wastewater collection, disposal and treatment. Let's figure out what wastewater is and its classification according to certain criteria.

All drains contain contaminants, so they need to be cleaned. What is the composition and properties of wastewater? The nature of contaminants contained in wastewater may vary.

Thus, household wastewater discharged from residential buildings contains mainly organic inclusions, while industrial wastewater can have various chemical and radiation contamination. This means that different purification methods must be used for such waters.

Types of contaminants in wastewater

Wastewater is classified according to the types of pollution, they are:

Mechanical. These are impurities and debris undissolved in water; such contaminants contain surface wastewater.

Advice! Storm or surface wastewater discharged from the territory of industrial enterprises may contain not only mechanical, but also chemical impurities.

Chemical. This type of pollution includes wastewater with the presence of dissolved or suspended organic or inorganic chemicals. Chemical contaminants may or may not be toxic.
Biological. This type of pollution implies the presence of various bacteria, fungi and other pathogenic microorganisms in the water.
Radioactive. This is wastewater contamination with radioactive substances.

Classification of wastewater by its origin

The characteristics of wastewater by method of origin make it possible to divide it into three groups. Main types of wastewater:

Atmospheric or rain. The composition of wastewater is determined by where the rainwater falls. Water flowing from roofs, asphalt and concrete surfaces of streets and squares carries with it a variety of debris, so such wastewater also needs to be cleaned.
Industrial wastewater is generated at various enterprises where water is used in the production cycle.
Domestic wastewater from residential buildings. This is water drained from plumbing fixtures - bathtubs, toilets, sinks, etc.

Advice! If the composition of atmospheric and domestic wastewater is more or less stable and well known, then industrial waters can contain a wide variety of contaminants depending on the range of substances and technologies used in the production cycle.

Composition of contaminants

Rainwater runoff is considered the cleanest, that is, containing the least amount of contaminants. As a rule, in this case, wastewater is filtered, that is, mechanical impurities are separated.

Industrial wastewater can have varying degrees of contamination. Among the cleanest is the water that is used to cool units and pipelines. Industrial wastewater may contain only inorganic or, on the contrary, organic impurities, or a combination of both types. Therefore, careful treatment of wastewater is required. Moreover, the quality of treated wastewater must be high. Ideally, industry should reuse wastewater.

Advice! One of the most dangerous organic pollutants is phenol. This substance is part of the wastewater from coke and petrochemical industries.

The composition of domestic wastewater is quite stable. They contain mainly organic impurities, as well as various types of bacteria, including pathogenic ones.

Assessing the degree of pollution

Since wastewater has a complex composition, it is extremely difficult to assess the content of each pollutant. Therefore, when conducting analyses, indicators are chosen that can characterize the overall properties of water without isolating and identifying individual substances.

For example, when assessing organoleptic indicators (color, smell), each substance that gives color or smell to water is not isolated. To determine the composition, a summary sanitary-chemical analysis of wastewater is used, which includes chemical, physico-chemical and sanitary-biological tests.

When conducting a full sanitary-chemical analysis, the following indicators are assessed:

Temperature, smell, color, transparency.
Acidity level (pH), dry residue, suspended solids content.
Chemical oxygen demand, biochemical oxygen demand (BOD), content of nitrogen compounds, phosphates, sulfides, chlorides.
Presence of heavy metals, radioactive and toxic substances.
Content of surfactants, petroleum products, dissolved oxygen.
Determination of microbial number, presence of coliform bacteria, helminth eggs.

Advice! In addition to standard analyzes at municipal wastewater treatment plants, additional studies may be carried out to determine the content of a group of substances that may be contained in wastewater discharged from local industrial enterprises.

Wastewater quantity accounting

To charge for the use of sewerage, it is necessary to account for wastewater, that is, measure its quantity. This is very important for large industrial enterprises where wastewater discharge is large.

For quantitative assessment, special metering devices are used - high-tech products that provide a high degree of measurement accuracy.

Cleaning methods

In nature, everything is provided for, so the water in reservoirs has the ability to self-purify. However, this process does not occur quickly, so natural purification methods will not cope with a large flow of wastewater. For this reason, wastewater disposal without preliminary treatment is prohibited.

Safe wastewater disposal is treatment to remove as much contaminants as possible from the water. Organizing wastewater treatment and disposal is an important task that needs to be solved when constructing a building. The methods by which wastewater is treated can be divided into several groups:

Mechanical;
Physico-chemical;
Chemical;
Biological.

Each of these methods can be used separately, but the best results can be achieved when using a combination of several methods.

Mechanical methods

When using mechanical cleaning, two methods are used:

Advocacy;
Filtration.

In the first case, wastewater settling tanks are used. Here, substances are divided into fractions depending on their specific gravity. For filtration, various filters are used that allow you to separate large inclusions.

When using the mechanical method, it is possible to achieve the removal of 65-70% of impurities from domestic wastewater and approximately 95% of impurities from storm drains. Therefore, settling or clarification is only the first stage; then domestic wastewater needs additional treatment.

Most often, wastewater treatment is carried out using biological methods. Additionally, wastewater disinfection can be applied using ozonizers or ultraviolet light.

Chemical methods

When using chemical methods, specially selected chemical reagents are added to the cleaned environment. These substances react with contaminants to form insoluble substances that settle to the bottom of the sump. When using a chemical method, it is possible to remove about 95% of contaminants dissolved in water and about 25% of undissolved substances.

Physico-chemical methods

When using these methods, wastewater is subjected to special treatment to remove both dissolved and undissolved contaminants. The most commonly used methods are:

Coagulation. In this case, special substances are introduced into the drain, under the influence of which small suspended particles stick together, forming large aggregates that settle to the bottom.
Flocculation. This process has the same principle as coagulation, but the reagents used when using it are different.
Extraction. This is a method of extracting certain substances from a liquid. It is quite expensive, so it is used when the extracted substances can be reused.
Ultrafiltration. Ultrafilters are used in industrial sewerage systems if the system provides for the use of recycled water. Ultrafiltration allows you to separate high molecular weight compounds from low molecular weight ones.

As a rule, physicochemical methods are used to process industrial wastewater, since it can contain a large number of different chemicals.

Bioremediation methods

Biological methods are used to process domestic wastewater containing a lot of organic matter. They are based on the use of naturally occurring bacteria, which are used in natural self-cleaning processes. During their life, bacteria process organic inclusions, decomposing them into safe components.

The simplest biotreatment methods are used in cesspools and septic tanks. Here, organic waste that has settled to the bottom undergoes anaerobic fermentation, that is, it is processed by microorganisms that can exist without oxygen.

In modern treatment plants, aerobic cleaning is additionally used; for this purpose, air oxygen is supplied to the working area. Aerobic processes are much faster and allow more contaminants to be removed. The biorefinery station has elements such as aerators and electric pumps, that is, it is volatile and requires a power supply.

Discharge of purified water

When creating a sewerage system, you need to think about how wastewater will be discharged. The simplest option is gravity drainage. However, such wastewater discharge is possible only if the soil has good absorbency. Otherwise, forced pumping of wastewater will be organized.

To organize forced pumping, it is necessary to use additional equipment. The purified liquid is discharged into a container in which a pump is installed for pumping. The volume of the container depends on the volume of water consumption and the performance of the septic tank.

A household drainage pump can be used to pump out wastewater. It is not advisable to use a fecal pump for pumping, since the use of this equipment is required when the liquid contains large inclusions, and if purification has already been carried out, then there are no such inclusions in the water.

The system is equipped with a float sensor, which will turn on the submersible wastewater pump after the liquid level reaches a certain level. Having finished pumping, the pump will automatically turn off.

So, wastewater is the result of water used in everyday life or in production. Discharge of wastewater without pre-treatment is prohibited, so sewage requires treatment. Cleaning methods are selected depending on the degree and composition of contaminants.

Thus, mechanical and biological types of treatment are used to treat household wastewater. Bioremediation of wastewater removes organic contaminants, but does not disinfect wastewater.

For this purpose, ultraviolet irradiation or ozonation of wastewater is carried out. Such disinfection of wastewater is necessary if the water is planned to be reused for technical purposes. Industrial wastewater may require the use of physicochemical and chemical treatment methods.

“Pollution of water bodies with domestic wastewater”

Introduction…………………………………………………………….

The main types of hydrosphere pollution…………………….. Domestic (fecal) wastewater………………………. Pollution by domestic wastewater……………………..

3.1 Consequences of pollution with domestic wastewater....

The impact of pollution on water bodies……………………………... Domestic wastewater treatment…………………………………… Discharge of wastewater into water bodies………………………… ……..

Conclusion………………………………………………………

Application……………………………………………………..

INTRODUCTION

The most well-known source of water pollution and the one that has traditionally received the most attention is domestic (or municipal) wastewater. Urban water consumption is usually estimated based on the average daily water consumption per person, which in the United States is approximately 750 liters and includes water for drinking, cooking and personal hygiene, for the operation of household plumbing fixtures, as well as for watering lawns and lawns, extinguishing fires, and washing streets and other urban needs. Almost all used water goes down the drain. Since a huge volume of feces enters wastewater every day, the main task of city services when processing domestic wastewater in the sewers of treatment plants is to remove pathogenic microorganisms. When insufficiently treated faecal waste is reused, the bacteria and viruses it contains can cause intestinal diseases (typhoid, cholera and dysentery), as well as hepatitis and polio. Soap, synthetic washing powders, disinfectants, bleaches and other household chemicals are present in dissolved form in wastewater. Paper waste comes from residential buildings, including toilet paper and baby diapers, waste from plant and animal food. Rain and melt water flows from the streets into sewers, often with sand or salt used to accelerate the melting of snow and ice on the roadways and sidewalks.

1. Main types of hydrosphere pollution

Pollution of water resources refers to any changes in the physical, chemical and biological properties of water in reservoirs in connection with the discharge of liquid, solid and gaseous substances into them that cause or may create inconvenience, making the water of these reservoirs dangerous for use, causing damage to the national economy, health and public safety. Sources of pollution are recognized as objects from which discharge or otherwise enter water bodies of harmful substances that worsen the quality of surface waters, limit their use, and also negatively affect the condition of the bottom and coastal water bodies.

Pollution of surface and groundwater can be divided into the following types:

mechanical - increase in the content of mechanical impurities, characteristic mainly of surface types of pollution;

chemical - presence of organic and inorganic substances of toxic and non-toxic effects in water;

bacterial and biological - the presence of various pathogenic microorganisms, fungi and small algae in the water;

("1") radioactive - presence of radioactive substances in surface or ground waters;

thermal - release of heated water from thermal and nuclear power plants into reservoirs.

The main sources of pollution and clogging of water bodies are insufficiently treated wastewater from industrial and municipal enterprises, large livestock complexes, production waste from the development of ore minerals; water from mines, mines, processing and rafting of timber; discharges from water and rail transport; waste from primary processing of flax, pesticides, etc. Pollutants entering natural bodies of water 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 changes in the chemical composition of water, in particular, the appearance of harmful substances in it, the presence of floating substances on the surface of the water and their deposition at the bottom of reservoirs.

Wastewater is divided into three groups: waste water, or fecal water; household, including drains from the galley, showers, laundries, etc.; sub-oil, or oil-containing.

For fan wastewater characterized by high bacterial contamination, as well as organic contamination (chemical oxygen demand reaches mg/l.). The volume of these waters is relatively small.

Domestic wastewater characterized by low organic pollution. This wastewater is usually discharged overboard the ship as it is generated. Dumping them is prohibited only in the sanitary protection zone.

Subsoil waters are formed in the engine rooms of ships. They are characterized by a high content of petroleum products.

Industrial wastewater is contaminated mainly with waste and emissions from production. Their quantitative and qualitative composition is diverse and depends on the industry and its technological processes; they are divided into two main groups: those containing inorganic impurities, including toxic ones, and those containing poisons.

The first group includes wastewater from soda, sulfate, nitrogen fertilizer plants, processing factories of lead, zinc, nickel ores, etc., which contain acids, alkalis, heavy metal ions, etc. Wastewater from this group mainly changes the physical properties of water.

Wastewater of the second group is discharged by oil refineries, petrochemical plants, organic synthesis enterprises, coke plants, etc. The wastewater contains various petroleum products, ammonia, aldehydes, resins, phenols and other harmful substances. The harmful effect of wastewater from this group lies mainly in oxidative processes, as a result of which the oxygen content in water decreases, the biochemical need for it increases, and the organoleptic characteristics of water deteriorate.

Pollution with wastewater as a result of industrial production, as well as municipal wastewater, leads to eutrophication reservoirs - their enrichment with nutrients, leading to excessive development of algae, and to the death of other aquatic ecosystems with stagnant water (lakes, ponds), and sometimes to swamping of the area.

Phenol is a rather harmful pollutant in industrial waters. It is found in wastewater from many petrochemical plants. At the same time, the biological processes of reservoirs and the process of their self-purification sharply decrease, and the water acquires a specific smell of carbolic acid.

The life of the population of reservoirs is adversely affected by wastewater from the pulp and paper industry. Oxidation of wood pulp is accompanied by the absorption of a significant amount of oxygen, which leads to the death of eggs, fry and adult fish. Fibers and other insoluble substances clog the water and impair its physicochemical properties. Fish and their food - invertebrates - are adversely affected by moth alloys. Rotting wood and bark release various tannins into the water. Resin and other extractive products decompose and absorb a lot of oxygen, causing the death of fish, especially juveniles and eggs. In addition, moth floats heavily clog rivers, and driftwood often completely clogs their bottom, depriving fish of spawning grounds and feeding places.

Oil and petroleum products at the present stage are the main pollutants of inland waters, waters and seas, and the World Ocean. Getting into water bodies, they create various forms of pollution: an oil film floating on the water, oil products dissolved or emulsified in water, heavy fractions settled to the bottom, etc. This complicates the processes of photosynthesis in water due to the cessation of access to sunlight, and also causes death of plants and animals. At the same time, the smell, taste, color, surface tension, viscosity of water changes, the amount of oxygen decreases, harmful organic substances appear, water acquires toxic properties and poses a threat not only to humans. 12 g of oil makes a ton of water unfit for consumption. Each ton of oil creates an oil film over an area of up to 12 square meters. km. Restoration of affected ecosystems takes 10-15 years.

Nuclear power plants pollute rivers with radioactive waste. Radioactive substances are concentrated by the smallest planktonic microorganisms and fish, then transmitted through the food chain to other animals. It has been established that the radioactivity of planktonic inhabitants is thousands of times higher than the water in which they live.

Wastewater with increased radioactivity (100 curies per 1 liter or more) must be disposed of in underground drainless pools and special reservoirs.

Population growth, the expansion of old cities and the emergence of new cities have significantly increased the flow of domestic wastewater into inland water bodies. These drains have become a source of pollution of rivers and lakes with pathogenic bacteria and helminths. To an even greater extent, synthetic detergents, widely used in everyday life, pollute water bodies. They are also widely used in industry and agriculture. The chemicals they contain, entering rivers and lakes with wastewater, have a significant impact on the biological and physical regime of water bodies. As a result, the ability of water to saturate with oxygen is reduced, and the activity of bacteria that mineralize organic matter is paralyzed.

The pollution of water bodies with pesticides and mineral fertilizers that fall from the fields along with streams of rain and melt water is of serious concern. As a result of research, for example, it has been proven that insecticides contained in water in the form of suspensions are dissolved in petroleum products that contaminate rivers and lakes. This interaction leads to a significant weakening of the oxidative functions of aquatic plants. Once in water bodies, pesticides accumulate in plankton, benthos, and fish, and enter the human body through the food chain, affecting both individual organs and the body as a whole.

2.Domestic (household) wastewater.

Domestic wastewater accounts for 20% of the total volume of wastewater entering surface water bodies. If the volumes of industrial wastewater and the amount of pollutants in them can be reduced through the introduction of recycling water supply systems, changes in the technology of wastewater treatment, then household wastewater is characterized by a constant increase in its volume, due to population growth, increased municipal water consumption, improvement sanitary and hygienic living conditions in modern cities and towns. The amount of pollutants in household wastewater is relatively stable - in the volume of pollution per inhabitant, which makes it possible to calculate the volume of discharged pollution depending on the number of residents, volume of water consumption, socio-economic way of life, etc. Average pollution standards per person per resident are shown in Table No. 1.

Amount of pollutants per person

Table 1

("3") 3. Pollution from domestic wastewater.

The oldest type of water pollution is direct human waste. In terms of dry matter, each adult “produces” about 20 kg of organic matter, 5 kg of nitrogen and 1 kg of phosphorus per year. Initially, these wastes were directly used as fertilizers, then

The first earthen latrines appeared. Some of the waste inevitably ended up in drinking water sources. That is why large cities already in ancient times began to build water pipelines from sources quite remote from crowded places. With the advent of water closets, the idea of a simple

solving the problem - diluting waste and removing it from the dump site. The volumes and then the composition of wastewater to be treated have changed significantly. Municipal wastewater now comes not only from residential buildings, but also from hospitals, canteens, laundries, small industrial enterprises, etc. Modern household wastewater, in addition to easily oxidized organic substances and nutrients, contains many substances that used in everyday use: detergents and surfactants, chemicals, medications, etc. Easily oxidizable organic substances entering watercourses and reservoirs are subjected to chemical and microbiological oxidation there. To measure the content of organic substances in water, it is customary to use the value of biochemical oxygen consumption over 5 days. (BOD5, BOD5 – Biochemical Oxygen Demand). It is determined by the difference in oxygen content in water when sampling and after five days of incubation without access to oxygen. BOD5, reflecting the content of easily oxidizable

organic matter in water is a universal indicator, using which you can compare the degree of pollution from different sources.

3.1 Consequences of pollution with domestic wastewater.

Easily oxidized organic matter, contained in excess in municipal wastewater, becomes a breeding ground for the development of many microorganisms, including pathogenic ones. Normal soil contains a large number of microorganisms that can cause severe infectious diseases. Drinking water is usually protected from the invasion of these

microorganisms in that the content of accessible food for bacteria (easily oxidized organic substances) is small and almost all of them are used by normal aquatic microflora. However, with a significant increase in the concentration of organic matter in water, soil pathogens find enough food sources for themselves and can become the source of an outbreak

In addition to the immediate danger of the development of pathogenic organisms in water contaminated with domestic wastewater, there is another indirect, unpleasant consequence for humans of this type of pollution. During the decomposition of organic matter (both chemical and microbiological), as we mentioned above,

oxygen is consumed. In the case of severe pollution, the content of oxygen dissolved in water drops so much that this is accompanied not only by fish kills, but also by the impossibility of normal functioning of microbiological communities.

The aquatic ecosystem is degrading. In running waters and reservoirs, the picture of the consequences of pollution from household wastewater looks different.

In flowing waters, four zones are formed, following each other downstream. They clearly show gradients in oxygen content (increase from the point of discharge downstream), nutrients and BOD5 (corresponding decrease), and species composition of biological communities.

The first zone is a zone of complete degradation, where mixing of wastewater and river water occurs. Next is a zone of active decomposition, in which microorganisms destroy most of the ingested organic matter. This is followed by zones of restoration of water quality and, finally, clean water.

Back at the beginning of the twentieth century. R. Kolkwitz and M. Marsson provided lists of indicator organisms for each of these zones, creating the so-called saprobity scale (from the Greek sapros - rotten). The first zone, polysaprobic, contains a significant amount of

quantity of unstable organic substances and products of their anaerobic decomposition, a lot of protein substances. There is no photosynthesis, and oxygen enters the water only from the atmosphere, being completely spent on oxidation. Anaerobic bacteria produce methane, Desulfovibrio desulphuricans reduces sulfates to hydrogen sulfide, which contributes to the formation of black iron sulfide. Due to this, the sludge is black, with the smell of hydrogen sulfide. There are a lot of saprophytic microflora, filamentous bacteria, sulfur bacteria, protozoa - ciliates, colorless flagellates, tubificid oligochaetes.

In the α-mesosaprobic zone that follows it, aerobic decomposition of organic substances occurs. Ammonium bacteria metabolize nitrogen compounds to form ammonia. High content of carbon dioxide, oxygen is still low, but hydrogen sulfide and methane are no longer present, BOD5 is tens of milligrams per

liter Saprophytic bacteria are numbered in tens and hundreds of thousands per 1 ml. Iron is present in oxide and ferrous forms.

Redox processes occur. Silt is gray in color. Organisms that have adapted to a lack of oxygen and a high carbon dioxide content predominate. There are many plant organisms with mixotrophic nutrition. Filamentous bacteria, fungi, oscillators, chlamydomonas, and euglena develop in the mass. There are sessile ciliates, rotifers, many

("4") flagellates. Lots of tubificides and chironomid larvae.

In the β-mesosaprobic zone there are practically no unstable organic substances; they are almost completely mineralized. Saprophytes – thousands of cells in 1 ml. The oxygen and carbon dioxide content fluctuates depending on the time of day. The silt is yellow, oxidative processes are taking place, there is a lot of detritus. Many organisms

with autotrophic nutrition, water blooms are observed. There are diatoms, green ones, and a lot of protococcal algae. Hornwort appears. Lots of rhizomes, sunflowers, ciliates, worms, mollusks, chironomid larvae. Crustaceans and fish are found.

The oligosaprobic zone corresponds to the zone of pure water. There is no flowering, the oxygen and carbon dioxide content is constant.

At the bottom there is little detritus, autotrophic organisms and worms, mollusks, chironomids. There are a lot of mayfly larvae, stoneflies, you can find sterlet, minnow, and trout.

In reservoirs of slow water exchange, the picture depends on the size of the reservoir and the regime of wastewater discharge. In large bodies of water (seas, large lakes) around a permanent source, concentrically located polymeso and oligosaprobic zones are formed. This picture can persist indefinitely if the self-purifying potential of the reservoir allows it to cope with the incoming load. If the reservoir is small, then it transforms as pollution enters from the oligosaprobic to the polysaprobic state, and with the removal of the load it can return to the oligosaprobic state.

4. The impact of pollution on water bodies

Pure water is transparent, colorless, odorless and tasteless, inhabited by many fish, plants and animals. Polluted waters are cloudy, have an unpleasant odor, are not suitable for drinking, and often contain large amounts of bacteria and algae. The water self-purification system (aeration with running water and sedimentation of suspended particles to the bottom) does not work due to an excess of anthropogenic pollutants in it.

Reduced oxygen content. Organic substances contained in wastewater are decomposed by enzymes of aerobic bacteria, which absorb oxygen dissolved in the water and release carbon dioxide as the organic residues are digested. Commonly known breakdown end products are carbon dioxide and water, but many other compounds can be formed. For example, bacteria convert nitrogen contained in waste into ammonia (NH3), which, when combined with sodium, potassium or other chemical elements, forms salts of nitric acid - nitrates. Sulfur is converted into hydrogen sulfide compounds (substances containing the radical - SH or hydrogen sulfide H2S), which gradually turn into sulfur (S) or sulfate ion (SO4-), which also forms salts.

In waters containing fecal matter, plant or animal residues coming from food industry enterprises, paper fibers and cellulose residues from pulp and paper industry enterprises, the decomposition processes proceed almost identically. Since aerobic bacteria use oxygen, the first result of the breakdown of organic residues is a decrease in the amount of oxygen dissolved in the receiving waters. It varies depending on temperature, and also to some extent on salinity and pressure. Fresh water at 20°C and intensive aeration contains 9.2 mg of dissolved oxygen in one liter. As the water temperature increases, this indicator decreases, and when it cools, it increases. According to the standards in force for the design of municipal wastewater treatment plants, the decomposition of organic substances contained in one liter of municipal wastewater of normal composition at a temperature of 20°C requires approximately 200 mg of oxygen over 5 days. This value, called biochemical oxygen demand (BOD), is used as the standard for calculating the amount of oxygen required to treat a given volume of wastewater. The BOD value of wastewater from tannery, meat processing and sugar refinery industries is much higher than that of municipal wastewater.

In small streams with fast currents, where the water is intensively mixed, oxygen coming from the atmosphere compensates for the depletion of its reserves dissolved in the water. At the same time, carbon dioxide formed during the decomposition of substances contained in wastewater evaporates into the atmosphere. This reduces the period of adverse effects of organic decomposition processes. Conversely, in bodies of water with weak currents, where the waters mix slowly and are isolated from the atmosphere, an inevitable decrease in oxygen content and an increase in carbon dioxide concentration entail serious changes. When the oxygen content decreases to a certain level, fish die and other living organisms begin to die, which, in turn, leads to an increase in the volume of decomposing organic matter.

Most fish die due to poisoning from industrial and agricultural wastewater, but many also die from a lack of oxygen in the water. Fish, like all living things, absorb oxygen and release carbon dioxide. If there is little oxygen in the water, but a high concentration of carbon dioxide, the intensity of their respiration decreases (it is known that water with a high content of carbonic acid, i.e., carbon dioxide dissolved in it, becomes acidic). In waters experiencing thermal pollution, conditions are often created that lead to the death of fish. There, the oxygen content decreases, since it is slightly soluble in warm water, but the need for oxygen increases sharply, since the rate of its consumption by aerobic bacteria and fish increases. Adding acids, such as sulfuric acid, to coal mine drainage water also significantly reduces the ability of some fish species to extract oxygen from the water.

5.Domestic wastewater treatment.

Sewerage is a complex of engineering structures and sanitary measures that ensure the collection and removal of contaminated wastewater outside populated areas and industrial enterprises, their purification, neutralization and disinfection. Cities and other populated areas discharge 22 billion m3 of wastewater per year through sewer systems. Of this, 76% passes through treatment facilities, including 94% through complete biological treatment facilities. 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 wastewater treatment plants to the established standards, and the remaining 92% is discharged as contaminated. Of these, 82% are discharged insufficiently purified and 18% without any purification. Most wastewater treatment plants are overloaded, and almost half require reconstruction.

Domestic wastewater treatment can be carried out using 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 on filtration and irrigation fields, in biological ponds, and artificial treatment is carried out on special equipment (biofilters, aeration tanks). Sludge is processed on sludge beds or in digesters.

With a public sewerage system, all types of wastewater from urban areas, including surface runoff, are discharged through one network of pipelines. The disadvantage of such a system is the periodic discharge of some industrial and domestic wastewater into water bodies through storm drains. Currently, the most widely used sewerage system in our country involves the construction of pipeline networks: through the production and household network, household and industrial wastewater is supplied to treatment facilities, and through the drain, as a rule, without treatment, it is discharged to the nearest water body rain and melt water, as well as water generated during watering and washing road surfaces. The most promising from the point of view of protecting water bodies from pollution by surface runoff from cities is a semi-separate 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. When jointly treating industrial and domestic wastewater, the content of suspended and floating substances, products that can destroy or clog communications, explosive and flammable 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 the cell membrane. Particularly toxic are salts of heavy metals, which can be arranged in order of decreasing toxicity: mercury, antimony, lead, cesium, cadmium, cobalt, nickel, copper, iron.

To disinfect wastewater, the dose of chlorine is selected so that the content of E. coli in water discharged into a reservoir does not exceed 1000 per liter, and the level of residual chlorine is at least 1.5 mg/l with 30-minute contact or 1 mg/l at 60-minute contact. Disinfection is carried out with liquid chlorine, bleach or sodium hypochlorite, obtained on site in electrolyzers. The chlorine management of sewage treatment facilities should allow the calculated dose of chlorine to be increased by 1.5 times.

6. Release of wastewater into water bodies

The amount of wastewater released into sewage facilities is determined using the maximum permissible discharge (MPD). The MDS is understood as the mass of a substance in wastewater, the maximum permissible for discharge with the established regime at a given point of a water body per unit of time in order to ensure water quality standards at the control point. The MDP is calculated based on the highest average hourly wastewater flow rate q (in m3/h) during the actual period of wastewater discharge.

(“5”) Reservoirs are polluted mainly as a result of the discharge of wastewater from industrial enterprises and populated areas into them. As a result of wastewater discharge, the physical properties of water change (temperature increases, transparency decreases, colors, tastes, and odors appear); floating substances appear on the surface of the reservoir, and sediment forms at the bottom; the chemical composition of water changes (the content of organic and inorganic substances increases, toxic substances appear, the oxygen content decreases, the active reaction of the environment changes, etc.); The qualitative and quantitative bacterial composition changes, and pathogenic bacteria appear. Polluted water bodies become unsuitable for drinking, and often for industrial water supply; lose their fishery importance, etc.

The general conditions for the release of wastewater of any category into surface water bodies are determined by their national economic significance and the nature of water use. After the release of wastewater, some deterioration in the quality of water in reservoirs is allowed, but this should not significantly affect its life and the possibility of further use of the reservoir as a source of water supply, for cultural and sports events, or for fishing purposes.

Monitoring the fulfillment of the conditions for discharging industrial wastewater into water bodies is carried out by sanitary-epidemiological stations and basin departments.

Water quality standards for water bodies for household, drinking and cultural and domestic water use establish the quality of water for reservoirs for two types of water use: the first type includes areas of reservoirs used as a source for centralized or non-centralized household and drinking water supply, as well as for water supply to food industry enterprises; to the second type - areas of reservoirs used for swimming, sports and recreation of the population, as well as those located within the boundaries of populated areas.

The assignment of reservoirs to one or another type of water use is carried out by the State Sanitary Inspection authorities, taking into account the prospects for the use of reservoirs.

The water quality standards for reservoirs given in the rules apply to sites located on flowing reservoirs 1 km above the nearest water use point downstream, and on non-flowing reservoirs and reservoirs 1 km on both sides of the water use point.

Much attention is paid to the prevention and elimination of pollution of coastal areas of the seas. The seawater quality standards that must be ensured when discharging wastewater apply to the water use area within the designated boundaries and to sites at a distance of 300 m to the sides from these boundaries. When using coastal areas of the seas as a recipient of industrial wastewater, the content of harmful substances in the sea should not exceed the maximum permissible concentrations established by sanitary-toxicological, general sanitary and organoleptic limiting hazard indicators. At the same time, the requirements for wastewater discharge are differentiated in relation to the nature of water use. The sea is considered not as a source of water supply, but as a healing, health-improving, cultural and everyday factor.

Pollutants entering rivers, lakes, reservoirs and seas make significant changes to the established regime and disrupt the equilibrium state of aquatic ecological systems. As a result of the processes of transformation of substances polluting water bodies, occurring under the influence of natural factors, water sources undergo a complete or partial restoration of their original properties. In this case, secondary decay products of contaminants may be formed, which have a negative impact on water quality.

Self-purification of water in reservoirs is a set of interconnected hydrodynamic, physico-chemical, microbiological and hydrobiological processes leading to the restoration of the original state of a water body. Due to the fact that wastewater from industrial enterprises may contain specific contaminants, their discharge into the city drainage network is limited by a number of requirements. Industrial wastewater released into the drainage network must not: disrupt the operation of networks and structures; have a destructive effect on the material of pipes and elements of treatment facilities; contain more than 500 mg/l of suspended and floating substances; contain substances that can clog networks or deposit on pipe walls; contain flammable impurities and dissolved gaseous substances capable of forming explosive mixtures; contain harmful substances that interfere with the biological treatment of wastewater or discharge into a body of water; have a temperature above 40 C. Industrial wastewater that does not meet these requirements must be pre-treated and only then discharged into the city drainage network.

Conclusion.

Domestic waste

Today, household wastewater is a big environmental and economic problem. From them, organic materials enter the hydrosphere. They decompose under the action of bacteria and consume oxygen. With sufficient oxygen supply, aerobic bacteria easily and quickly transform sewage into environmentally friendly material. If there is insufficient access of oxygen to the wastewater, aerobic bacteria slow down their activity, as a result of which anaerobic bacteria begin to develop and the process of rotting begins.

Domestic wastewater that has not been subjected to biological treatment or has not been treated well may contain pathogenic bacteria and viruses that, if released into drinking water, can cause dangerous diseases. Vegetables fertilized with wastewater treatment sludge may also be contaminated. Typhoid fever outbreaks are often caused by oysters and other aquatic invertebrates whose habitats are contaminated with untreated sewage.

Agricultural wastewater contains phosphorus, nitrogen and is often a source of nutrients for plankton and algae. With an increased content of these elements in the water, vegetation rapidly develops, which absorbs oxygen. This, in turn, negatively affects the activity of microorganisms that process organic substances.

Phenols, pesticides, and detergents also enter the water with sewage, the process of decomposition of which occurs slowly or does not decompose at all. Then, through food chains from fish and other aquatic animals, they enter the human body and negatively affect human health, which can subsequently cause various infectious and chronic diseases.

At the moment, developments are known that will not allow us to reach an environmental impasse - these are technologies for waste-free production and biological processing of wastewater into environmentally friendly, useful resources. Biological treatment is one of the most promising areas, and all the best from biological treatment is contained in the Topas autonomous sewage system.

APPLICATION

Article 250 of the Criminal Code of the Russian Federation Water pollution

1. Pollution, clogging, depletion of surface or underground waters, sources of drinking water supply, or any other change in their natural properties, if these acts entailed causing significant harm to the animal or plant world, fish stocks, forestry or agriculture, is punishable by a fine of one hundred to two hundred minimum wages or in the amount of wages or other income of the convicted person for a period of one to two months, or deprivation of the right to hold certain positions or engage in certain activities for a period of up to five years, or correctional labor for a period of up to one year, or arrest for up to three months.

2. The same acts that entailed harm to human health or mass death of animals, as well as those committed on the territory of a nature reserve or sanctuary or in a zone of environmental disaster or in a zone of environmental emergency, are punishable by a fine in the amount of two hundred to five hundred times the minimum wage or in the amount of wages or other income of the convicted person for a period of two to five months, or correctional labor for a term of one to two years, or imprisonment for a term of up to three years.

("6") 3. Acts provided for in parts one or two of this article, resulting in the death of a person through negligence, are punishable by imprisonment for a term of two to five years.

1. The object of the crime in question is public relations in the field of water protection and environmental safety. The subject of the crime is surface water, including surface watercourses and reservoirs on them, surface reservoirs, glaciers and snowflakes, groundwater (aquifer, basins, deposits and natural outlet of groundwater).

Inland sea waters, the territorial sea of the Russian Federation, and the open waters of the World Ocean are not the subject of this crime.

2. The objective side of the crime consists of pollution, clogging, depletion or other change in the natural properties of the above-mentioned components of the hydrosphere with untreated and non-neutralized wastewater, waste and garbage or toxic or aggressive in relation to the quality of the environment products (oil, petroleum products, chemicals) of industrial , agricultural, municipal and other enterprises and organizations.

In accordance with Art. 1 of the Water Code of the Russian Federation, adopted by the State Duma on October 18, 1995, clogging of water bodies - discharge or otherwise entering water bodies, as well as the formation of harmful substances in them that worsen the quality of surface and ground water, limit the use or negatively affect the condition of the bottom and shores of such objects.

Clogging of water bodies is the discharge or otherwise entry into water bodies of objects or suspended particles that worsen the condition and complicate the use of such objects.

Water depletion is a steady reduction in reserves and deterioration in the quality of surface and groundwater.

The quality of the environment and its main objects, including water, is determined using special standards - maximum permissible concentrations of harmful substances (MPC). Discharges of untreated wastewater, industrial and agricultural waste into rivers, lakes, reservoirs, and other inland water bodies sharply increase the maximum permissible concentration in water sources and thereby significantly reduce their quality. Discharge - the entry of harmful substances in wastewater into a water body is determined by GOST.

References:

Furon R. The problem of water on the globe. L., 1966 Lvovich water from pollution. L., 1977, Shvetsov and water. M., 1979 Lvovich and life: Water resources, their transformation and protection. M., 1986

The most valuable natural resource is water. It plays an exceptional role in metabolic processes. Human health directly depends on the quality of the water they consume. Therefore, it is so important to develop technological processes that minimize the types of wastewater pollution.

There are more than 100 thousand rivers in Russia, their annual flow is 4700 km 3. Analysis of water resources shows that the threat of depletion is currently increasing and water may become scarce. Today, about 60% of the world's population already lacks fresh water.

The reason for the growing shortage of fresh water is population growth, as well as unregulated deforestation and pollution of water bodies due to an unreasonable attitude towards the protection of water resources. It is estimated that there will be a shortage of fresh water within this century. Therefore, it is very important to pay attention to the integrated, economical use of water resources.

Runoff from industrial enterprises, agriculture, and public utilities has a particularly strong influence on the lack of fresh water. A small city, consuming 600 m 3 of clean water daily, produces 500 m 3 of wastewater.

Clean water without a filter is almost impossible these days.

The shortage of fresh water is caused not by its irreversible consumption, but by the increasingly increasing pollution of water bodies by industrial and domestic wastewater. Severely polluted wastewater comes from the petrochemical, metallurgical, oil refining, chemical, pulp and paper, and food industries. The incorrect use of pesticides and fertilizers in agriculture causes enormous harm.

Wastewater is varied in its composition, which depends on the type of pollutants that enter it. Effluents from the chemical industry, processing and mining enterprises are very harmful.

Discharge of wastewater at high temperatures, for example from thermal power plants, leads to the accumulation of organic substances and disrupts the biorhythm of the reservoir.

It is difficult to purify wastewater from synthetic surfactants contained in detergents. Sometimes they are even present in drinking water. Surfactants significantly impair the self-cleaning ability of water bodies. They enter water bodies as wastewater from laundries, baths, and detergent manufacturers. Surfactants and CMC are also used to intensify production at light industry enterprises, during ore dressing, and during the separation of products in the chemical industry.

Pesticides entering them along with melt and rainwater during cultivation of fields, as well as with water from cotton and rice plantations, cause enormous harm to reservoirs.

Radioactive contamination is dangerous to human life and health. This phenomenon is observed during testing of nuclear weapons under water, during violations of the purification regime for uranium ore, as well as during the processing of nuclear fuel.

Types of wastewater pollution

Basically, all wastewater contains 3 types of contaminants:

Mineral. These include sand, ore and clay inclusions, solutions of mineral salts, alkalis and acids;
Vegetable. These include fruit residues and adhesive substances of animal origin. In them, the main chemical substance is carbon;
Biological and bacterial. This is wastewater from slaughterhouses, municipal services, and biofactories. They contain microorganisms and molds.

Types of wastewater

The following types of wastewater are distinguished:

Industrial waste

They can be divided into:

Polluted. Pollution occurs through the above route;
Conditionally clean. These include, for example, water for cooling heat engines;
Domestic and household wastewater. These include wastewater from public buildings, hospitals, kitchens, canteens;
Agricultural runoff. They contain large quantities of chemical fertilizers and pesticides;
Atmospheric effluents. They are formed by runoff from industrial sites during melting snow and rain.

Surface and underground waters

They are characterized by the following types of pollution:

Mechanical contamination. This is mainly characteristic of surface types of pollution. These include an increased content of mechanical impurities;
Chemical pollution. It is characterized by the presence in water of inorganic and organic substances of a non-toxic and toxic nature;
Biological and bacteriological. The water contains pathogenic microorganisms, fungi and small algae.
Radioactive. There are radioactive substances in the water;
Thermal. This type of pollution is observed when water from nuclear and thermal power plants with elevated temperatures is discharged into reservoirs.

The main source of water pollution is poorly treated wastewater from municipal and industrial enterprises. Pollutants qualitatively change the composition of water. This manifests itself in a change in its physical properties, an unpleasant odor and taste appears, and harmful substances appear in it, which either float on the surface of reservoirs or are deposited at the bottom.

Chemical pollution

Output of surface wastewater with impurities

The quantitative and qualitative composition of all contaminants is varied. But all chemical pollution can be divided into two groups:

The first category includes pollution containing inorganic impurities. These include wastewater from sulphate and soda plants and processing plants. In their composition, they contain large quantities of heavy metal ions, alkalis and acids. They change the quality composition of water.
The second group includes wastewater from oil refineries, petrochemical plants, organic synthesis enterprises, and coke production plants. Wastewater contains large quantities of phenols, aldehydes, resins, ammonia, and petroleum products. Their harmful effect is that the organoleptic characteristics of water deteriorate, the oxygen content in it decreases, and the biochemical need for it increases.

Currently, the main pollutant of water bodies is oil and petroleum products. When they enter water, they create a film on its surface, and heavy fractions settle to the bottom. Taste, color, viscosity, surface tension changes. Water acquires toxic properties and poses a threat to humans and animals.

Wastewater from petrochemical plants contains phenol. When it gets into water bodies, the biological processes occurring in them sharply decrease and the process of self-purification of water is disrupted. There is a carbolic acid smell in the water.

Pulp and paper industry enterprises have a detrimental effect on the life of water bodies. The wood mass oxidizes, a significant consumption of oxygen occurs and, as a result, fry and adult fish die. Insoluble substances and fibers worsen the physical and chemical properties of water. Mole alloys have a harmful effect on water bodies. Tannins are released from bark and rotting wood into the water. The resin absorbs oxygen, which leads to the death of fish. In addition, moth alloys clog rivers and clog their bottoms. At the same time, fish are deprived of spawning grounds and feeding grounds.

Radioactive contamination

Nuclear power plants are polluted with radioactive waste. Radioactive pollutants are concentrated by small planktonic organisms and fish. Then they are transmitted along the chain to other organisms. If wastewater has increased radioactivity (100 curies/l), then it is necessary to bury it in underground drainless reservoirs and special tanks.

Biological contamination

The world's population is growing, old cities are expanding and new ones are growing, which leads to an increase in runoff into inland water bodies. Domestic wastewater is a source of pollution of rivers and lakes with helminths and pathogenic bacteria.

Wastewater contains 60% organic substances. These include biological pollution in medical and sanitary waters, municipal waters and waste from wool washing and tanning enterprises.

When treating wastewater, the greatest difficulties are caused by organic impurities. When they rot, they poison the soil, air and water. Wastewater must be removed outside the cities and organic matter must be mineralized. The total volume of microorganisms in wastewater is about 1 m3 per 100 m3 of wastewater. Among the bacteria and various microorganisms there are also pathogenic ones, for example, the causative agents of cholera, typhoid fever, dysentery and other diseases. Most of the wastewater is potentially hazardous to humans and animals. To prevent water bodies from becoming polluted with harmful substances, wastewater must be treated. Partial purification also occurs in the reservoir itself. The degree of wastewater treatment is determined by a special calculation and agreed with the fishery and sanitary inspection authorities.

Thermal pollution

If heated water from thermal power plants is discharged into reservoirs, this causes thermal pollution. Warm water contains less oxygen, and the thermal regime changes dramatically. This has a negative impact on the flora and fauna of the reservoir. Blue-green algae begin to develop in it, which has a detrimental effect on the number of inhabitants of reservoirs.

Today, the task of protecting water resources from pollution and depletion and their rational use is particularly acute. One of the areas of work to protect water resources is the use of drainless water supply cycles. In this case, wastewater does not need to be discharged; it can be reused in technological processes. Drainless cycles will eliminate water discharges.

The removal of valuable impurities from wastewater will significantly reduce the degree of pollution of wastewater. If water is used to cool the system, then air cooling should be considered, which will reduce overall water consumption by 80%. In this regard, it is very important to develop new equipment that uses a minimum of water for cooling.

The increase in the whirlpool is significantly influenced by the introduction of wastewater treatment methods with high efficiency, for example, physical and chemical ones, where the use of reagents is the most effective. The active implementation of the physicochemical method together with biochemical treatment can significantly solve the problems of wastewater treatment. In the near future it is planned to carry out wastewater treatment using membrane methods.

Wastewater treatment methods

Wastewater treatment methods are divided into:

Mechanical;
Chemical;
Physico-chemical;
Biological;
Thermal.

All methods of wastewater treatment can be divided into destructive and recuperative. The latter involve the extraction of valuable substances from wastewater for further processing. In destructive methods, all substances polluting wastewater are destroyed. And the products of their destruction are removed from the water in the form of sediment or gases.

The following wastewater treatment methods are distinguished:

Cleaning from emulsified and suspended impurities. To do this, coarse impurities are separated by sedimentation, filtration and straining, flotation and centrifugal sedimentation. Fine substances are separated by flocculation, electroflotation and electrocoagulation;
Purification of impurities dissolved in wastewater. For this, ion exchange, distillation, reverse osmosis, freezing, electrodialysis, and purification methods using chemical reagents are used;
Cleaning from organic impurities;
Regenerative methods: rectification, clarification, ultrafiltration, reverse osmosis.
Destructive: vapor phase, liquid phase, electrochemical, radiation oxidation;
Gas removal: reagent methods, heating, blowing.

In practice, three methods are used to treat all wastewater. The first has been used for a long time and is considered the most economical. Wastewater is discharged into large watercourses, where it is diluted, aerated and neutralized naturally. Currently, this method has shown to be ineffective.

The second method is to remove organic matter and solid contaminants through mechanical, biological and chemical treatment. This method is most often used at municipal wastewater treatment plants.

The third method involves reducing the volume of wastewater by changing technological processes.

Despite the fact that many enterprises are trying to make their cycles closed, the most radical solution to the problem of wastewater treatment is the construction of the most modern treatment facilities. In such structures, mechanical cleaning is provided at the first stage. A sieve or grate is installed along the path of wastewater flow, with the help of which suspended particles and floating objects are captured. Sand and other inorganic substances settle in sand traps. Oil traps and grease traps trap oil products and fats. The flocculent particles are captured after settling using chemical coagulants.

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