Purification of industrial and household drains. Joint treatment of industrial and domestic wastewater. Purification of industrial effluents with a change in their chemical composition

The historical location of industrial complexes in residential areas of populated areas is not optimal. Water supply and sanitation systems in such agglomerations are also joint for residential and industrial areas. On the large enterprises, as a rule, has its own water management system with a full technological cycle from water intake to its purification, neutralization and disposal of the solid phase.
Main elements of the water management system locality and its interaction with the environment natural environment are presented in fig. 4.15.
Water intake facilities take natural water from a surface water source. The pumping station of the first rise through pressure pipelines delivers it to the treatment plant. Here the water is purified to drinking quality and from tanks pumping station the second rise is supplied to the settlement, as a rule, having a ring water supply network. Water is used for drinking, household needs, watering streets and plantings, at local industries.

Rice. 4.15. The main elements of the water management of the settlement and their relationship with the natural environment:
1 - water intake facilities; 2 - pumping station of the first lift; 3 - treatment facilities; 4 - reservoirs; 5 - pumping station of the second rise; 6 - water supply network; 7 - sewer network; 8 - sewer pumping station; 9 - mechanical cleaning; 10 - biological treatment; 11 - disinfection of waters; 12 - biological ponds; 13 - discharge of purified water; 14 - rain network, artesian wells; 15 - treatment facilities; 16 - industrial enterprise; 17 - water circulation cycles; 18 - coolers
Used water (wastewater) is diverted outside the city through a closed sewer network and is supplied to the city treatment facilities by the main sewer pumping station.
Here, wastewater undergoes mechanical and biological treatment, disinfected and fed to biological ponds, where it is purified in natural conditions. After the ponds, the water in its qualities differs slightly from the water of a natural reservoir and can be discharged into a river, lake, etc.
Atmospheric water, which is discharged by the rain network, is purified from suspended solids and oil products at facilities, and is also discharged into biological ponds or directly into a water receiver (reservoir).
The city can also be supplied with drinking water from underground sources - artesian wells.
An industrial enterprise consumes drinking and process water. Industrial water is most often used in water circulation cycles. For cooling, water is reused after the temperature in the coolers decreases.
Waste water from industrial enterprises containing specific pollution, as well as rain and melt water from the territories of industrial sites, can be discharged into the water disposal system of a settlement and be subjected to biological treatment together with city waste water after passing through local treatment facilities.
Water supply systems industrial enterprises depending on the water and technological processes, they can be direct-flow, repeated (sequential) and reverse. Depending on the technological purpose, water in the circulating water supply system can be subjected to various treatments. In circulating water supply systems, irretrievable water losses (production, evaporation, weathering, splashing, sludge, purge flow) are compensated by an additional, i.e. make-up, amount of fresh water from the source.
Balance schemes for the consumption of water, raw materials, and pollution are one of the source materials when compiling environmental passports of the enterprise in accordance with GOST 17.0.04-90 in the section on the characteristics of water consumption, water disposal and water treatment, as well as passports for the water management of settlements.
Joint schemes for water supply and wastewater disposal of industrial enterprises and populated areas are developed during design on the basis of a technical and economic comparison of options in order to comprehensively solve the water management problems of a district, city or region.
cleaning Wastewater is ensured through the implementation of the following technical solutions and measures.
Mechanical cleaning - improvement of the hydrodynamic regimes of existing settling facilities; the use of mesh installations instead of settling tanks; pre-treatment of wastewater before clarification with coagulants; expanding the use of technological processes for water purification, using centrifugal forces to separate suspensions and emulsions, instead of gravitational ones; improvement of existing and development of new filter installations.
Chemical cleaning - the use of more active coagulants; improvement of hydrodynamic and mass-transfer characteristics, ensuring the completeness of hydrolysis, mixing, reaction; reuse slags and sediments of chemical water treatment; isolation and utilization in the main or secondary production of reaction products; organization of a rational system for the disposal of industrial wastewater, ensuring their mutual purification after combining at local treatment facilities.
Physico-chemical purification - expansion and improvement of the processes of hyper-, ultrafiltration, extraction, adsorption, ion exchange, which make it possible to isolate and return products to the main production, and use purified water after adjusting the composition to standard values in circulating water supply; development and creation of new selective types of sorbents from wastewater for reuse, widespread use of liquid and solid industrial waste in technological processes; the development of low-energy efficient processes, which include the use of electricity obtained from biolysis in water treatment, as well as galvanic coagulation; development of a mobile service network for servicing subscribers for the regeneration of sorbents, electrochemical separation heavy metals on the cathodes of special installations, which will allow returning products to the technology, regenerating sorbents with the production of secondary raw materials and returning them to the water purification cycle; development of methods for preliminary physical and chemical effects on treated waters; physical treatment (magnetization, ultrasonic, high-frequency), leading to a change in the physico-chemical characteristics and, accordingly, to a deeper degree of pollution from the water.
Biological treatment - application of the method of preliminary anaerobic treatment of wastewater; use of artificial biomass carriers; widespread use of biosorption methods; regulation of the ratio of groups of microorganisms; the use of higher aquatic vegetation (eichornia water or water hyacinth, pistia, calamus, etc.) as an independent phytoreactor for the treatment of wastewater from agricultural complexes with the production of biomass and its use for livestock feed or in the production of biogas; the use of a symbiotic algobacterial community (algae + bacteria) in the treatment and post-treatment of wastewater with artificial lighting during the dark period of the day with an intensity of 120 lx / m. Carbon dioxide produced by bacteria during the oxidation of organic substances is absorbed by algae, and oxygen released as a result of photosynthesis is used by microorganisms as an electron acceptor in metabolism. This achieves deep wastewater treatment and does not require blowers, compressors for biooxidants.
Currently, the greatest technological and environmental difficulty is not wastewater treatment, but the problem of processing and disposal of their solid phase.
The amount of the formed solid phase at the treatment plant depends on the genesis of the initial composition and consumption of wastewater, the method of their treatment and averages 0.01-3% of the volume. Humidity of the solid phase ranges from 85 (construction industry enterprises) to 99.8% (activated sludge).
The main tasks of the treatment of sludge and sewage sludge are dehydration, disinfection and disposal.
Depending on the ash content, they can be of three types:
predominantly mineral (ash content over 70%);
predominantly organic (ash content less than 30%);
mixed (ash content 30-70%).
At present, there is industrial experience in the return to the main production of wastewater treatment sludge from glass, optical-mechanical, metallurgical enterprises, factories for the production of building products, some chemical industries, and also as additives in auxiliary productions - meat-packing plants; dairies (technical fats, lanolin, fat substitutes); hydrolysis plants (protein-vitamin concentrates); Pulp-cardboard-paper mills (production of wood-fiber boards, cardboard, cellulose).
Sludge disposal is a complex multi-variant problem, the main issue of which is the prevention of secondary pollution of the environment by heavy metals. The most common way to dispose of wastewater treatment sludge is to store them in industrial waste landfills (sludge is treated with cement, bitumen, glass or polymer binders). There is experience in the disposal of heavy metal sludge in the production of building ceramics, bricks, and tiles. Modern environmental approaches to the formation of a wastewater disposal system for electroplating industries take into account the goals of recycling.
When treating wastewater, including galvanic water, it is necessary to increase the one-time costs for the complete separation of flows, which will ultimately increase the environmental friendliness of the technology. In countries with market economies, such approaches have already been implemented 12-15 years ago.
Taking into account the existing experience of a number of countries, in the future we should expect the appearance of treatment facilities with the capture and neutralization of aerosols from aeration bio-oxidants, as well as the placement of treatment facilities in underground workings.

Based on the materials of the book - "Life Safety" Edited by prof. E. A. Arustamova.

The main elements of the water management system of a settlement and its interaction with the environment under one environment are shown in Fig. 21. Water intake facilities take natural water from a surface water source. The pumping station of the first lift through pressure pipelines delivers it to the treatment plant. Here, the water is purified to drinking quality and from the reservoirs the pumping station of the second lift is supplied to the settlement, which, as a rule, has a water supply network. Water is used for food, household needs, watering streets and plantings, local industries.

Used water (sewage) is diverted outside the city through a closed network and is supplied to city facilities by the main sewage pumping station.

Here, wastewater undergoes mechanical and biological treatment, disinfected and fed to biological ponds, where the ponds are cleaned under natural conditions, the water quality slightly differs from the water of a natural reservoir, maybe into a river, lake, etc.

The amount of the formed solid phase at the treatment plant depends on the genesis of the initial composition and consumption of wastewater, the method of their treatment and averages 0.01 - 3% of the volume. Humidity of the solid phase ranges from 85 (construction industry enterprises) to 99.8% (activated sludge).

The main tasks of the treatment of sludge and sewage sludge are dehydration, disinfection and disposal.

Depending on the ash content, they can be of three types;

Mainly mineral (ash content over 70%),

Predominantly organic (ash content less than 30)

Mixed (ash content 30 - 70%),

At present, there is industrial experience of returning sewage treatment sludge to the main production in glass, optical-mechanical, metallurgical enterprises, factories for the production of building products, some chemical industries, and also as additives to auxiliary industries - meat processing plants; dairies (technical fats, lanolin, fat substitutes); hydrolysis plants (protein-vitamin concentrates); pulp and paper mill (production of fibreboard, cardboard, pulp).

Sludge disposal is a complex multi-variant problem, the main issue of which is the prevention of secondary pollution of the environment by metals. The most common way to dispose of wastewater treatment sludge is in industrial waste landfills (the sludge is treated with cement, bitumen, glass or binders). There is experience in the utilization of metal sludge in the production of building bricks and tiles. Modern ecological formation of galvanic wastewater systems take into account the goals of civilization.

Wastewater treatment is a variety of processes for the removal of contaminants contained in industrial and domestic wastewater. Treatment activities typically take place in either fixed or mobile treatment plants and systems.

Cleaning usually occurs in several different technological stages and includes, as a rule, mandatory mechanical cleaning (sometimes multi-stage), biological and disinfection.

To improve the quality of cleaning and water parameters, a physico-chemical stage can be applied before disinfection, which includes several different technologies (for example, electroflotation).

The mechanical stage is designed to retain insoluble impurities. Large contaminants are retained by gratings and sieves. Waste from the grates is either crushed and sent for joint processing with sludge from sewage treatment plants, or taken to places where solid domestic and industrial waste is processed. The wastewater then passes through sand traps and grease traps. In the former, sand, broken glass, etc. are retained, while the latter remove hydrophobic substances from the surface of the water (through flotation). Sand from sand traps can be used in road works. Mechanical water purification removes up to 60-70% of mineral contaminants, the reduction in biological oxygen consumption is 20-30%.

Preliminary treatment of wastewater entering the treatment facilities is carried out in order to prepare them for biological treatment. On the mechanical stage retention of insoluble impurities.

Facilities for mechanical wastewater treatment:

§ gratings (or UFS - a self-cleaning filtering device) and sieves;

§ sand traps;

§ primary settling tanks;

§ membrane elements;

§ septic tanks.

Grids are used to retain large contaminants of organic and mineral origin, and sieves are used for a more complete separation of coarse impurities. The maximum width of the grating openings is 16 mm. Waste from the grates is either crushed and sent for joint processing with sludge from sewage treatment plants, or taken to places where solid domestic and industrial waste is processed.

Then the effluents pass through sand traps, where fine particles (sand, slag, broken glass, etc.) are deposited under the action of gravity, and grease traps, in which hydrophobic substances are removed from the water surface by flotation. Sand from sandboxes is usually stockpiled or used in roadworks.

Recently, membrane technology has become a promising method for wastewater treatment. Wastewater treatment using advanced membrane technology is used in combination with traditional methods for deeper treatment of wastewater and their return to the production cycle.

The wastewater thus purified is transferred to primary settling tanks for the separation of suspended solids. The decrease in BOD is 20-40%.

As a result of mechanical cleaning, up to 60-70% of mineral contaminants are removed, and BOD5 is reduced by 30%. In addition, the mechanical stage of treatment is important for creating a uniform flow of wastewater (averaging) and avoids fluctuations in the volume of wastewater at the biological stage.

This method of wastewater treatment allows cleaning up to 75%, but, since only insoluble impurities are released, mechanical method does not remove organic compounds dissolved in water.

This method is one of the most primitive, so the increasingly complex requirements for water purity required further development of purification technologies.

The stage of biological treatment involves the reduction of the organic component of wastewater with the help of aerobic or anaerobic microorganisms.

From a technical point of view, there are several options for biological treatment. At the moment, the most common are activated sludge (aerotanks), biofilters and digesters (anaerobic fermentation).

In the primary settling tanks at this stage, suspended organic matter is deposited. At the next stage, the activated sludge is disposed of.

Biological treatment involves the degradation of the organic component of wastewater by microorganisms (bacteria and protozoa).

At this stage, wastewater is mineralized, organic nitrogen and phosphorus are removed, the main goal is to reduce BOD5.

Primary settling tanks, where water enters at this stage, are designed to settle suspended organic matter. These are reinforced concrete tanks five meters deep and 40 and 54 meters in diameter. Effluents are fed into their centers from below, the sediment is collected in the central pit by scrapers passing along the entire plane of the bottom, and a special float from above drives all the pollution lighter than water into the bunker.

Also in biological treatment, after primary clarifiers, there is a second line of radial clarifiers. These are Ilosos. They are designed to remove activated sludge from the bottom of the secondary settling tanks of industrial and domestic wastewater treatment plants.

Most experts call this method the most effective way to purify water. Its peculiarity lies in the use of special bacteria that affect the mineralization of contaminants. Under the influence of these bacteria, all contaminants break down into separate components that are completely harmless to human health.

This method is a reliable protection against water decay, which at the same time is the most environmentally friendly.

There are several types of biological devices designed to clean water bodies. These include biofilters, biological ponds and aeration tanks.

· Biofilters work as follows: sewage is passed through a layer of coarse-grained material covered with a thin film of bacteria. It is this film that is the source of biological oxidation processes.

· Biological ponds use all living organisms that live in the reservoir to purify water.

Aerotanks are huge tanks made of reinforced concrete. Bacteria and microscopic animals actively develop in aeration tanks, where a suitable environment has been created for them: wastewater organic matter and an excess of oxygen entering the aeration tanks. These bacteria, developing, secrete enzymes that can mineralize organic pollution. Sludge, consisting of bacteria, quickly settles and is separated from the purified water.

Before applying the biological method, it is often recommended to apply mechanical and then chemical cleaning in order to remove pathogenic microbes and bacteria.

Often, for this purpose, water is purified with liquid chlorine or bleach. You can use other methods for disinfection, such as ozonation, ultrasound, etc.

The biological treatment method is most common in the treatment of municipal wastewater. In addition, it is often used for the disposal of waste from oil refineries and the pulp and paper industry, as it is the most effective in this area and for this kind of pollution.

In physical-chemical purification, various chemical methods can be applied to improve the parameters, for example, additional sedimentation of phosphorus with Fe and Al salts, chlorination, ozonation, as well as physical-chemical methods such as electroflotation.

This method consists in the combined use of ultrasound and ozone. This method allows you to remove finely dispersed and dissolved inorganic impurities from water, destroy poorly oxidized and organic substances.

The most common variant of this method is electrolysis. The task of electrolysis is to destroy organic matter in wastewater. It also allows you to extract from water and inorganic substances - various metals, acids, etc. This cleaning method is most effective at copper and lead enterprises, in the paint and varnish industry. Purification by electrolysis is carried out using special devices - electrolyzers.

In addition, there are other physicochemical cleaning methods - coagulation, oxidation, extraction, sorption, etc. Each specific method requires a thorough study of the situation and a certain choice in favor of the most effective, but at the same time the most harmless cleaning method.

This cleaning method is especially attractive because it has a disinfecting property. These properties are explained design features cleaning system that uses ozone and ultrasound.

The essence of the chemical method is the use of various reagents that enter into chemical reactions with pollutants and turn them into insoluble precipitates.

Thanks to chemical treatment, the amount of insoluble impurities in water is reduced by 95%, but soluble impurities are reduced by only 25%.

A significant disadvantage of this method is the high cost of chemical reagents, which makes it inaccessible to a wide range of people. Therefore, the chemical method is most often used by entrepreneurs whose business is related to the production or large factories and organizations that cause great damage to the environment and therefore take responsibility for its safety. This method is most often used in industry and production.

Chemical wastewater treatment methods are based on the application chemical reactions. As a result of which contaminants are converted into compounds that are safer for the consumer or are easily released in the form of precipitation. Chlorination and ozonation of wastewater containing organic impurities, as well as cyanides and other odorous inorganic substances, should be singled out as a special group of chemical methods. Chlorination and ozonation are most often used for post-treatment and neutralization drinking water at city waterworks.

1. precipitation

2. oxidation-reduction

During thermal treatment, liquid wastes of petroleum products and other combustible substances are burned in furnaces and burners.

1. fire concentration

2. fire disposal

Waste water disinfection

For the final disinfection of wastewater intended for discharge onto the terrain or into a reservoir, ultraviolet irradiation installations are used.

For disinfection of biologically treated wastewater, along with ultraviolet irradiation, which is usually used at treatment facilities in large cities, chlorine treatment for 30 minutes is also used.

Chlorine has long been used as the main disinfectant in almost all wastewater treatment cities in Russia. Since chlorine is quite toxic and dangerous, treatment plants in many cities of Russia are already actively considering other reagents for wastewater disinfection, such as hypochlorite, dezavid and ozonation.

Combined method.

The essence of the combined wastewater treatment method is the simultaneous use of two or more treatment methods to achieve the best result.

The choice of treatment methods and the order of their use depends on the specific features of the reservoir and the degree of water pollution.

As a rule, first of all, mechanical cleaning is used, which removes the bulk of insoluble inorganic contaminants.

The second stage is biological treatment.

Physical and chemical cleaning methods such as ultrasound, ozonation, electrolysis are used as subsequent disinfection.

wastewater treatment

The state of the environment largely depends on the quality of industrial wastewater treatment. Every year the situation is only getting worse, so the task of developing more modern and efficient systems water treatment enterprises is particularly acute. They can work according to a single scheme - for example, the organization's management signs an agreement with utilities on draining wastewater into a centralized sewer in the form in which they are, or after pre-treatment.

Standards for the composition of industrial effluents for discharge into the sewer and industrial wastewater treatment

Industrial effluents contain various aggressive substances that destroy city sewage treatment plants and sewer pipelines. When they enter a body of water, they negative influence both on the composition of water and on the living organisms in it. Therefore, before cleaning it is necessary to check the maximum allowable concentrations of biological, chemical substances and take action. Effluent requirements for without fail taken into account when designing the reconstruction, installation of industrial facilities. Factories should operate on technologies with a minimum amount of waste or no waste at all, and water after treatment should be reused - this will help save the resources of our planet and protect the environment from negative external influences.

The main requirements for wastewater discharged into the central sewerage system:

BOD - no more than the maximum allowable value specified in project documentation to the treatment plant;
drains should not cause failures or stoppages in the operation of sewage, treatment facilities;
wastewater should not have a temperature of more than 40 degrees and a pH of more than 6.5-9.0;
the presence of sand, shavings, abrasive particles in drains is unacceptable (they are main reason formation of precipitation in sewer units);
the drains should not contain impurities that clog grates and pipes;
the absence of aggressive components that cause the destruction of pipes and other cleaning elements - 100%;
there should be no explosive components in the composition of wastewater - as well as biodegradable, viral, toxic, bacterial and radioactive impurities.

In those situations when the discharged effluents do not meet the specified parameters, they are pretreated.

Types of industrial wastewater pollution

In the course of treatment, all substances negative for the environment must be removed from the effluents. The main types of impurities:

coarse suspended particles - to eliminate them, methods such as screening, settling and filtration are used;
coarse emulsified substances - separation, filtration and flotation;
microparticles - first filtration is carried out, then coagulation, flocculation and pressure flotation;
stable emulsions - they are removed using thin-layer sedimentation, pressure flotation, electroflotation;
colloidal particles - requires microfiltration and electroflotation;
oils - separation, flotation, and then electroflotation are carried out;
phenols - biopurification, ozonation, sorption using activated carbon, flotation, coagulation;
organics - biological treatment, ozonation and final sorption activated carbon;
heavy metals - first electroflotation is carried out, then settling, electrocoagulation, electrodialysis, ultrafiltration and ion exchange;
cyanides - chemical oxidation, electroflotation and electrochemical oxidation are used to remove them;
tetravalent chromium - first, chemical reduction of water is carried out, then electroflotation and electrocoagulation;
trivalent chromium - electroflotation, ion exchange, precipitation and filtration;
sulfates - they are removed by settling with reagents and further filtration, the final stage of purification is reverse osmosis;
chlorides - reverse osmosis, evaporation in a vacuum environment, electrodialysis;
salts - nanofiltration, reverse osmosis treatment, electrodialysis, vacuum evaporation;
Surfactants - activated carbon sorption, ozonation, flotation, ultrafiltration.

All sewage pollution is divided into chemical, mechanical, thermal, biological and radioactive. In every industry, the composition of effluents will be different. Inorganics, including toxic ones, are usually present in the waters of nitrogen, sulfate, and soda enterprises that work with acids, ores, alkalis, and heavy metals. Organics are most often found in organic synthesis plants, etc. The third pollution - a mixture of organics and inorganics - is formed in effluents as a result of galvanic treatment.

Classification of industrial wastewater

Since different enterprises use certain harmful substances in their work, the nature of wastewater pollution will be different. Conventionally, according to the types of pollution, industrial wastewater is divided into 5 groups:

The first one contains impurities of suspended particles, mechanical inclusions (including metal hydroxides).
The second - it includes oil-containing impurities, oil emulsions.
The third is impurities of volatile substances.
Fourth - cleaning solutions.
Fifth - organic and inorganic, impurities have pronounced toxic properties (these are metal ions, chromium compounds, cyanides).

Methods of purification of industrial effluents. How industrial wastewater is treated

Various methods are used to remove contaminants from industrial effluents. The choice of purification method depends on the initial composition of the waters and their required quality after purification. If there are several pollutants, combined methods are used. The main ways to remove impurities:

- straining, settling, filtering.
Chemical - neutralization, flocculation, neutralization.
Physico-chemical - and blowing.

The most popular cleaning method is settling, but it has its drawbacks - for example, the long duration of the process of removing impurities and the relatively low percentage of removal of harmful substances (50-70% is already considered a good indicator). Flotation is a more efficient, but at the same time expensive solution. The cleaning efficiency of this method, subject to the technology, can reach 98%.

Reagent treatment significantly increases the cleaning performance - up to 100% of mechanical impurities and up to 99.5% of emulsions, oil products. The disadvantage of this method is the high cost and complexity of maintaining the treatment plant. Reagentless coagulation is used to remove metals and their oxides.

Stripping or desorption are the main ways to deal with dissolved gases and surfactants. To remove detergents from water, combined methods are used - this can be ion exchange, extraction, coagulation, adsorption, destructive destruction, foam separation and / or chemical precipitation. The optimal combination is selected taking into account the composition of the initial effluents and the requirements for them.

Effluent from pickling lines is subjected to chemical treatment, which is able to reduce alkalinity or acidity, precipitate and coagulate salts of heavy metals. Depending on the production capacity, diluted and concentrated solutions are either mixed and then neutralized, clarified, or neutralized (separately) and clarified solutions in different concentrations.

Purification of industrial effluents with a change in their chemical composition

The chemical and physical composition of wastewater determines the set of methods at each stage of water treatment. Some stages in the absence of certain contaminants can be excluded. Purification of industrial effluents with a change in their chemical composition suggests:

cleaning, accompanied by the formation of sparingly soluble electrolytes;
purification, accompanied by the formation of complex or slightly dissociated compounds;
purification in the process of decay and synthesis;
thermolysis cleaning;
purification in redox, electrochemical processes.

The use of biological methods for the treatment of wastewater from industrial enterprises

When deciding on the advisability of using wastewater from enterprises, it is necessary to take into account such a moment as the presence of pollutants in wastewater that are prone to biochemical destruction. Also, the following factors influence the purification efficiency - the presence of toxic substances, the level of nutrition of the biomass, the structure of impurities, biogenic elements, the active reaction of the environment, and increased mineralization. That is, biotreatment is used only for those effluents that meet fairly strict criteria.

In which case can industrial effluents be discharged into the general city sewerage system without hindrance?

Wastewater from industrial enterprises almost always contains various impurities that adversely affect the performance of the sewer network, urban treatment facilities of a settlement, and water bodies (if they are discharged into them). Therefore, prior to cleaning, control over the content of the maximum permissible concentration of harmful impurities is carried out. Enterprises need to apply waste-free and low-waste technologies, recycling and re-water supply systems.

Requirements for industrial effluents for discharge into the central sewer

When planning the discharge of wastewater into the sewer network, you need to make sure that they comply with established standards, namely:

BOD20 does not exceed the indicator specified in the construction project;
interruptions in the operation of the sewerage network and sewage treatment plants will not cause sewage;
the temperature of the drains does not exceed 40 degrees, and the pH is in the range of 6.5-9;
there are no impurities that can lead to clogging of pipes, wells and grates in the sewer, as well as substances that can cause the destruction of pipelines.

Also, the drains should not contain flammable, explosive gases, impurities, non-biodegradable substances, toxic pollutants, surfactants. Effluent COD should be higher than BOD5, but not more than 2.5 times.

The process of urbanization and, in particular, the expansion of communal services complicates the tasks of urban service organizations. The fight against sewage pollution is especially important in this regard, since the waste from the consumption of household fluids has a direct impact on the hydrological system of the area. In this regard, more effective means of minimizing the negative processes of environmental impact are being developed. Today, wastewater treatment is organized taking into account several factors for the elimination of harmful microorganisms. The main method of water treatment is still the arrangement of mechanical filtering stations, but more and more complex installations are appearing that also perform high-quality biological water treatment.

Features of modern wastewater treatment

Engineering equipment is developing in general directions that focus on improving ergonomics and reliability. Therefore, modern sewage drains are multifunctional, efficient and easy to manage. Both industrial and domestic wastewater filtration systems are equipped with control panels with a wide range of settings.

In addition, the developers of sewer and septic systems projects strive to rationalize communication networks as much as possible, optimizing energy resources as well. In other words, wastewater treatment in some nodes can also be connected to complex systems home or business engineering management. And this is not to mention the increase in the basic operational capabilities of cleaning equipment, which is achieved through the use of high-tech

mechanical cleaning

The whole cleaning process is divided into several stages, which have significant technological differences. The stage of mechanical filtration is primary and at the same time multi-stage. The simplest mechanism for such cleaning can be observed on the streets in the form of metal, concrete or plastic gratings that trap debris, leaves, stones and other large elements. In the future, wastewater can be sent through the sewer channel to special centrifuges and hydrocyclones. Also, a special strainer is used to trap microscopic particles - in essence, this is a filtration cleaning station. The drain, thanks to such equipment, can be cleaned of elements up to 0.25 mm in size. Together, the cleaning steps at this point can eliminate about 80% of foreign bodies in the waste fluid.

Biological treatment

Means of this kind of cleaning are usually used as a continuation of mechanical filtration. It can be said that the basic purification by strainers prepares the liquid for deeper processing by biological stations. However, both methods work on different principles. That is, it is wrong to assume that mechanical filtration traps large particles, and biological installations - small ones. The second option focuses on the environmental neutralization of water, which does not cause chemical harm during maintenance and after its release into water bodies. To date, the biological treatment of wastewater, the main goal is the elimination of organic matter or its processing. As a result, the composition of the liquid medium retains only dissolved nitrates and oxygen. In practice, such cleaning is implemented in two ways - natural or artificial. In the first case, wastewater is dispersed into and into artificial purification is carried out in special aeration tanks that release environmentally friendly water into reservoirs.

Chemical and thermal cleaning methods

From the point of view of eliminating the negative processes of decomposition in the sewage environment, one of the most effective methods is chemical reagent. As a rule, this group of methods is based on redox reactions, which essentially cancel some reactions, replacing them with others that are less environmentally hazardous. But the most effective method of combating pollution in wastewater is thermal exposure. Implemented this method with the help of furnace installations and burners in which the liquid is burned. Wastewater treatment by the fire method is also practiced without the use of furnace structures. Technologically, this method involves spraying a liquid in a finely dispersed state into a special torch formed during the combustion of gaseous fuel. As a result, water evaporates, which eliminates harmful compounds.

Sludge disposal

New technologies, which ensure the complete elimination of decomposition products, are not yet used at all treatment facilities. Moreover, such a principle does not always justify itself economically. Therefore, traditional cleaning channels are still common, the operation of which leaves sediments. New technologies in such recycling processes manifest themselves at the final stage of waste disposal. In particular, digesters are used. These are massive reinforced concrete tanks in which biogas is formed by fermentation. As a result, methane fuel is formed, which can later be used in boiler houses instead of traditional fuel. Also, complex wastewater treatment with sludge elimination involves the use of mechanical dehydration methods using special devices- centrifuges, belt or chamber pressing plants. In the future, the products of such processing, depending on the chemical composition, can be used in agriculture like fertilizer.

Conclusion

At this stage in the development of sewer systems, many manufacturers are solving the problem of a complete transition to one of the cleaning methods. This is related to the fact that technical organization several stages of processing contaminated liquid is expensive and requires the connection of large resources in the maintenance process. As an alternative, a biological wastewater treatment plant is considered, which also provides for the functions of mechanical processing, but only as auxiliary stages. However, this option cannot be called universal, since biological aerotanks lose in terms of the efficiency of removing harmful particles to the same thermal cleaning. Therefore, it is still advisable to approach the solution of the problem of wastewater treatment through the development of projects that take into account the individual conditions and requirements of the treatment equipment.