Depending on the wastewater entering the sewer network, city sewers are divided into common and separate.

In the first case, melt and rainwater enters the sewerage system along with domestic wastewater. With separate sewerage, melt and rainwater is directed through separately laid drains (storm drains) without treatment into open water bodies (ponds, rivers, lakes, etc.).

A separate type of sewerage is the most common method that requires less labor and material costs. Wastewater from city buildings is directed to yard lines and then to city sewer pipes, which are connected to the city sewer. For the movement of drains, pipes are laid with a slope and gradual penetration into the ground. If the level of burial exceeds the level of a reservoir or river into which wastewater is released, then a pumping station with fecal pumps is installed at the end of the collector, which pumps wastewater to the city sewerage treatment plant through a pressure collector.

City wastewater treatment methods

Treatment methods depend on the composition of the effluent, so they are very diverse. In the city sewerage system, the first stage is mechanical cleaning in sand traps, grates and settling tanks, in which contaminants that are not dissolved in wastewater are retained.

Sediments (sludge) accumulated in settling tanks rot in digesters. Rotting here is accelerated by heating and mixing the sediment. The methane gas released during decomposition is used as fuel for the needs of stations. Dehydrated, decayed and dried sludge is used as fertilizer.

The next stage of wastewater treatment is biological treatment - with the help of microorganisms that feed in the presence of oxygen on organic contaminants contained in wastewater.

There are 2 types of biological treatment:

* natural. In this case, the runoff is passed through the soil specially prepared for this purpose - in the fields of irrigation or filtration;

* artificial treatment facilities for urban sewerage in aerotanks - special tanks in which effluents and activated sludge added to them are blown with air coming from an aeration station (compressors). The next stage of artificial treatment is secondary settling tanks, in which activated sludge is released, which is directed further to aerotanks. The effluents treated here are further disinfected by electrolysis, or with the help of gaseous (liquid) chlorine, and enter open water bodies.

Water disposal- a complex of technological processes, engineering structures and equipment for the disposal of waste, storm and melt water from settlements, industrial facilities, agriculture and transport infrastructure.

Water disposal should be considered in two aspects - the actual removal of wastewater from the place of formation to the place of discharge and the treatment of wastewater before being discharged into a water body.

The history of the development of wastewater disposal in Russia is relatively young - no more than two centuries ago, with the advent of low-rise construction and dense urban development, goldmen appeared on the streets - professional sewage collectors who were taken out of the city in barrels. The Zolotar case was replaced by a sewer network for the discharge of sewage, i.e. household and household wastewater into the river flowing through the city. Water disposal into a water body was first carried out without treatment, by the end of the 19th century. with cleaning in the filtration fields and only in the 30s. 20th century in Russia, namely in Moscow, high-tech treatment facilities for urban sewerage appear. The general and strict requirement for drainage was the construction site treatment facilities and, accordingly, to the point of discharge of treated wastewater into the river - always below the city outside the dense population. In the era of intensive civil construction and urbanization of the Russian population, this principle of construction began to be violated: for example, Moscow covered all its wastewater treatment plants and wastewater outlets with dense housing developments. This is also practiced in other cities of Russia.

Wastewater or runoff from cities is extremely diverse in composition and sanitary and environmental hazards; they can be classified into seven groups:

From the types of wastewater considered, liquid radioactive waste was removed, which is isolated and subject to special treatment and disposal of radioactive concentrate.

Within each group, the composition and properties of wastewater are very diverse.

Wastewater Treatment Methods

Bringing wastewater to the standard indicators for the composition of pollutants is carried out at treatment facilities using various technological stages of treatment, among which are the following:

1. mechanical treatment is the primary stage of the wastewater treatment process, at which coarse pollutants (solid impurities) are removed during settling, filtration or flotation processes. Coarse particles are removed by gratings, sieves, sand traps, grease traps, oil traps, settling tanks and other engineering structures;
2. chemical treatment - various chemical reagents are added to wastewater that react with pollutants. Such reactions include oxidation and reduction; reactions leading to the formation of compounds that precipitate; reactions accompanied by gas evolution;
3. physical and chemical treatment - during these processes, finely dispersed, dissolved inorganic and organic substances are removed from the wastewater composition. This group includes such technologies as electrolysis and electrocoagulation, coagulation, flocculation, etc.;
4. biological purification is based on the ability of microorganisms to use organic pollutants as a source of nutrition, leading to complete (mineralization) or partial destruction of the structure of substances, i.e. their removal. Biological wastewater treatment can be carried out in bioponds, filtration fields, aerotanks (reservoirs with forced aeration and a high density of communities of microorganisms, protozoa, invertebrates), membrane bioreactors.

Wastewater treatment plant

In Russia, direct responsibility for the choice of treatment technology rests with the operating organizations, referred to in our country as “vodokanals”. This term is derived from two words: water supply and sewerage. Such a combination of two industries of different types of activity is uncharacteristic for the EU countries, the USA and Canada. Water supply is the production and supply of a commodity (clean drinking water); sewerage, i.e., water disposal is the provision of sanitary, hygienic and environmental services.

One of the largest wastewater treatment plants in the world are the wastewater treatment plants serving Moscow. Kuryanovskiye and Lyuberetskiye wastewater treatment facilities are capable of removing 3.125 and 3.0 million m 3 of wastewater daily, respectively. Treatment facilities of greater capacity are located only in China and a few cities in the United States.

Impact on water bodies

Each identified group of wastewater has an impact on the ecological situation in the water body - the recipient. The local consequences of polluted wastewater disposal can become an environmental and sanitary problem for large river basins and sea coasts.

For example, the metropolis of Moscow with the actual number of people living in the city at the same time, about 18–20 million people, has a decisive influence on the quality of water in the Oka-Volga basin. At present, half of the expenditure of the river. Moscow is urban wastewater, including surface runoff.

The discharge of sewage from settlements into small rivers often completely forms the composition and flow of water in the river. For example, the flow of water in the river. The desna increases from 0.92 to 1.66 m 3 /s after the discharge of wastewater from the Yuzhnobutovsky treatment facilities (OS), into the river. Pekhorka - from 1.16 to 8.40 m 3 / s after the Lyubertsy OS, in the river. Similar - from 1.85 to 2.70 m 3 / s after the Zelenograd OS.

Waste water quality

At present, for a number of reasons, the sewage treatment facilities of the municipal sewerage of the cities of the Russian Federation are not able to fully fulfill their main function - to purify wastewater, bringing it to standard indicators. In the Russian Federation in 2011, the total volume of wastewater discharges amounted to 48,095 million m 3, of which only 3.8% are legally treated and 33% (15,966 million m 3) are polluted (including 6.86% are discharged without treatment at all) . More than 60% of wastewater discharges into water bodies fall on the share of municipal sewage treatment facilities, and only 13-15% of them are classified as treated according to the norm.

Despite the tendency to reduce the volume of polluted wastewater, this does not lead to an improvement in the quality of wastewater.

The main problems of wastewater treatment in the Russian Federation

If in the largest cities the problems of water disposal are being systematically solved, then in medium, small and in most large settlements the treatment facilities of the city sewerage are in a state of decline. The main reasons for the low efficiency of treatment facilities: lack of budget funds for the reconstruction and modernization of treatment facilities; non-compliance with the technological regime of their operation; non-compliance of the composition of incoming wastewater with treatment technologies; significant physical deterioration of existing treatment facilities.

G.V. Adzhienko, V.G. Adzhienko

Today we will once again focus on a topic close to each of us without exception :)

Most people don't think about what happens to what they flush when they press the toilet button. Leaked and flowed away, that's business. In such a large city as Moscow, no less than four million cubic meters of sewage flows into the sewer system every day. This is about the same as the amount of water flowing in the Moskva River in a day in front of the Kremlin. All this huge volume of waste water needs to be cleaned and this task is very difficult.

There are two largest wastewater treatment plants in Moscow, approximately the same size. Each of them cleans up half of what Moscow "produces". I'm already talking about the Kuryanovsky station. Today I will talk about the Lyubertsy station - we will again go over the main stages of water purification, but we will also touch on one very important topic - how at treatment stations they fight unpleasant odors with the help of low-temperature plasma and perfume industry waste and why this problem has become more relevant than ever .

To start, a little history. For the first time, sewerage "came" to the area of ​​modern Lyubertsy at the beginning of the 20th century. Then the Lyubertsy irrigation fields were created, on which wastewater, even old technology percolated through the earth and thereby cleansed. Over time, this technology became unacceptable for the ever-increasing amount of wastewater, and in 1963 a new treatment plant, the Lyuberetskaya, was built. A little later, another station was built - Novoluberetskaya, which actually borders on the first one and uses part of its infrastructure. In fact, now it is one large cleaning station, but consisting of two parts - the old and the new.

Let's look at the map - on the left, in the west - the old part of the station, on the right, in the east - the new one:

The area of ​​the station is huge, in a straight line from corner to corner about two kilometers.

As it is not difficult to guess, there is a smell coming from the station. Previously, few people worried about it, but now this problem has become relevant for two main reasons:

1) When the station was built, in the 60s, almost no one lived around it. There was a small village nearby, where the station workers themselves lived. Then this area was far, far from Moscow. Right now there is a lot of building going on. The station is actually surrounded by new buildings from all sides and there will be even more of them. New houses are being built even on the former sludge sites of the station (fields where the sludge left over from wastewater treatment was brought). As a result, residents of nearby houses are forced to periodically sniff "sewer" smells, and of course they constantly complain.

2) Sewer water has become more concentrated than before, in Soviet times. This happened due to the fact that the volume of water used recently has been strongly shrunk, while they did not go to the toilet less, but on the contrary - the population has grown. There are quite a few reasons why the "diluting" water has become much less:
a) the use of meters - water has become more economical to use;
b) the use of more modern plumbing - it is less and less common to see a running faucet or toilet bowl;
c) the use of more economical household appliances - washing machines, dishwashers, etc.;
d) the closure of a huge number of industrial enterprises that consumed a lot of water - AZLK, ZIL, Hammer and Sickle (partially), etc.
As a result, if the station during construction was calculated for a volume of 800 liters of water per person per day, now this figure is actually no more than 200. An increase in concentration and a decrease in flow led to a number of side effects- in sewer pipes designed for a larger flow, sediment began to be deposited, leading to unpleasant odors. The station itself began to smell more.

To combat the smell, Mosvodokanal, which is in charge of the treatment facilities, is carrying out a phased reconstruction of the facilities, using several different ways getting rid of odors, which will be discussed below.

Let's go in order, or rather, the flow of water. Waste water from Moscow enters the station through the Luberetsky sewer canal, which is a huge underground collector filled with sewage. The channel is gravity-flowing and runs at a very shallow depth for almost its entire length, and sometimes even above the ground. Its scale can be estimated from the roof of the administrative building of the treatment plant:

The width of the channel is about 15 meters (divided into three parts), the height is 3 meters.

At the station, the channel enters the so-called receiving chamber, from where it is divided into two streams - part goes to the old part of the station, part to the new one. The receiver looks like this:

The channel itself comes from the right-behind, and the stream divided into two parts leaves through the green channels in the background, each of which can be blocked by the so-called gate valve - a special shutter (dark structures in the photo). Here you can see the first innovation to combat odors. The receiving chamber is completely covered with metal sheets. Previously, it looked like a "pool" filled with fecal water, but now they are not visible, naturally, a solid metal coating almost completely covers the smell.

For technological purposes, only a very small hatch was left, lifting which you can enjoy the whole bouquet of smells. Hello from walsk :)

These huge gates allow you to block the channels coming from the receiving chamber if necessary.

From the receiving chamber there are two channels. They, too, were open quite recently, but now they are completely covered with a metal ceiling.

Under the ceiling, gases released from wastewater accumulate. This is mainly methane and hydrogen sulfide - both gases are explosive at high concentrations, so the space under the ceiling must be ventilated, but the next problem arises - if you just put a fan, then the whole point of the ceiling will simply disappear - the smell will get out. Therefore, to solve the problem, ICD "Horizon" has developed and manufactured a special unit for air purification. The installation is located in a separate booth and a ventilation pipe from the channel goes to it.

This installation is experimental, for testing the technology. In the near future, such installations will be massively installed at treatment facilities and sewerage pumping stations, of which there are more than 150 units in Moscow and from which unpleasant odors also come. On the right in the photo - one of the developers and testers of the installation - Alexander Pozinovskiy.

The principle of operation of the installation is as follows:
polluted air is fed into four vertical stainless steel pipes from below. In the same pipes there are electrodes, to which a high voltage (tens of thousands of volts) is applied several hundred times per second, resulting in discharges and low-temperature plasma. When interacting with it, most smelling gases turn into a liquid state and settle on the walls of the pipes. A thin layer of water constantly flows down the walls of the pipes, with which these substances mix. Water circulates in a circle, the water tank is the blue container on the right, below in the photo. The purified air exits from the top of the stainless pipes and is simply released into the atmosphere.
For those who are more interested in more details - a photo of the stand, where everything is explained.

For patriots - the installation is completely designed and created in Russia, with the exception of the power stabilizer (below in the closet in the photo). High voltage part of the installation:

Since the installation is experimental - it has an additional measuring equipment- gas analyzer and oscilloscope.

The oscilloscope shows the voltage across the capacitors. During each discharge, the capacitors are discharged and the process of their charge is clearly visible on the oscillogram.

Two tubes go to the gas analyzer - one takes air before installation, the other after. In addition, there is a tap that allows you to select the tube that is connected to the gas analyzer sensor. Alexander first shows us the "dirty" air. The content of hydrogen sulfide - 10.3 mg/m 3 . After switching the tap - the content drops to almost zero: 0.0-0.1.

Each of the channels is also blocked by a separate gate. Generally speaking, there are a huge number of them at the station - they stick out here and there :)

After cleaning from large debris, the water enters the sand traps, which, again, it is not difficult to guess from the name, are designed to remove small solid particles. The principle of operation of sand traps is quite simple - in fact, it is a long rectangular tank in which water moves at a certain speed, as a result, the sand simply has time to settle. Also, air is supplied there, which contributes to the process. From below, the sand is removed using special mechanisms.

As is often the case in technology, the idea is simple, but the execution is complex. So here - visually, this is the most "fancy" design on the way of water purification.

Sand traps were chosen by seagulls. In general, there were a lot of seagulls at the Lyubertsy station, but it was on the sand traps that they were the most.

I enlarged the photo already at home and laughed at their appearance - funny birds. They are called lake gulls. No, they don’t have a dark head because they constantly dip it where they don’t need it, it’s just such a design feature :)
Soon, however, it will not be easy for them - many open water surfaces at the station will be covered.

Let's get back to technology. In the photo - the bottom of the sand trap (not working at the moment). It is there that the sand settles and from there it is removed.

After sand traps, water again enters the common channel.

Here you can see what all the channels at the station looked like before they were covered. This channel is shutting down right now.

The frame is made of stainless steel, like most metal structures in the sewer. The matter is that in the sewerage very aggressive environment - water full of any substances, 100% humidity, gases promoting corrosion. Ordinary iron very quickly turns into dust in such conditions.

Work is being carried out directly above the existing channel - since this is one of the two main channels, it cannot be turned off (Muscovites will not wait :)).

In the photo there is a small level difference, about 50 centimeters. The bottom in this place is made of a special shape to dampen the horizontal speed of the water. As a result - very active seething.

After sand traps, water enters the primary sedimentation tanks. In the photo - in the foreground is a chamber into which water enters, from which it enters the central part of the sump in the background.

The classic sump looks like this:

And without water - like this:

Dirty water enters from the hole in the center of the sump and enters the general volume. In the sump itself, the suspension contained in the dirty water gradually settles to the bottom, along which the sludge rake is constantly moving, fixed on a truss rotating in a circle. The scraper rakes the sediment into a special annular tray, and from it, in turn, it falls into a round pit, from where it is pumped out through a pipe by special pumps. Excess water flows into the channel laid around the sump and from there into the pipe.

Primary clarifiers are another source of unpleasant odors in the plant, as they contain actually dirty (purified only from solid impurities) sewer water. In order to get rid of the smell, Moskvodokanal decided to cover the sedimentation tanks, but then a big problem arose. The sump diameter is 54 meters (!). Photo with a person for scale:

At the same time, if you make a roof, then, firstly, it must withstand the snow load in winter, and secondly, it must have only one support in the center - it is impossible to make supports above the sump itself, because. there is a farm going on all the time. As a result, an elegant decision was made - to make the floor floating.

The ceiling is assembled from floating stainless steel blocks. Moreover, the outer ring of blocks is fixed motionless, and the inner part rotates afloat, together with the truss.

This decision turned out to be very successful, because. firstly, there is no problem with the snow load, and secondly, there is no air volume that would have to be ventilated and additionally cleaned.

According to Mosvodokanal, this design reduced odorous gas emissions by 97%.

This settling tank was the first and experimental one where this technology was tested. The experiment was recognized as successful, and now other sedimentation tanks are being covered in a similar way at the Kuryanovskaya station. Over time, all primary clarifiers will be covered in this way.

However, the process of reconstruction is lengthy - it is impossible to turn off the entire station at once, the settling tanks can only be reconstructed one after another, turning off one by one. And yes, it takes a lot of money. Therefore, until all the sedimentation tanks are covered, the third method of dealing with odors is used - spraying neutralizing substances.

Special sprayers have been installed around the primary clarifiers, which create a cloud of odor neutralizing substances. The substances themselves smell not to say very pleasant or unpleasant, but rather specific, however, their task is not to mask the smell, but to neutralize it. Unfortunately, I did not remember the specific substances that are used, but as they said at the station, these are waste products from the perfume industry in France.

For spraying, special nozzles are used that create particles with a diameter of 5-10 microns. The pressure in the pipes, if I'm not mistaken, is 6-8 atmospheres.

After the primary settling tanks, water enters the aerotanks - long concrete tanks. They supply a huge amount of air through pipes, and also contain activated sludge - the basis of the entire method of biological water treatment. Activated sludge recycles "waste", while rapidly multiplying. The process is similar to what happens in nature in water bodies, but proceeds many times faster due to warm water, a large amount of air and silt.

Air is supplied from the main machine room, where the turbo blowers are installed. Three turrets above the building are air intakes. The process of supplying air requires a huge amount of electricity, and the interruption of the supply of air leads to catastrophic consequences, because. activated sludge dies very quickly, and its recovery can take months (!).

Aerotanks, oddly enough, do not particularly exude strong unpleasant odors, so it is not planned to cover them.

This photo shows how dirty water enters the aerotank (dark) and mixes with activated sludge (brown).

Some of the facilities are currently disabled and mothballed, for the reasons I wrote about at the beginning of the post - the decrease in water flow in recent years.

After the aerotanks, the water enters the secondary settling tanks. Structurally, they completely repeat the primary ones. Their purpose is to separate activated sludge from already purified water.

Mothballed secondary clarifiers.

Secondary settling tanks do not smell - in fact, there is already clean water.

The water collected in the annular trough of the sump flows into the pipe. Part of the water undergoes additional UV disinfection and merges into the Pekhorka River, while part of the water goes through an underground channel to the Moskva River.

The settled activated sludge is used to produce methane, which is then stored in semi-underground tanks - methane tanks and used at its own thermal power plant.

The spent sludge is sent to sludge sites in the Moscow region, where it is additionally dehydrated and either buried or burned.

Lastly, a panorama of the station from the roof of the administrative building. Click to enlarge.

I express my deep gratitude for the invitation to the press service Mosvodokanal, as well as separately to Alexander Churbanov - director of the Lyubertsy treatment facilities. Thank you

Before designing treatment facilities for domestic wastewater or other types of wastewater, it is important to find out their volume (the amount of wastewater generated over a certain period of time), the presence of impurities (toxic, insoluble, abrasive, etc.) and other parameters.

Types of wastewater

Wastewater treatment plants are installed on drains various types.

• Household waste- these are drains from plumbing fixtures (wash basins, sinks, toilet bowls, etc.) of residential buildings, including private houses, as well as institutions, public buildings. Domestic wastewater is dangerous culture medium for pathogenic bacteria.
• Industrial waste formed in enterprises. The category is characterized by the possible presence of various impurities, some of which significantly complicate the purification process. Industrial wastewater treatment plants are usually complex in design and have several treatment stages. The completeness of such facilities is selected in accordance with the composition of wastewater. Industrial wastewater can be toxic, acidic, alkaline, with mechanical impurities and even radioactive.
• Storm drains due to the method of formation, they are also called superficial. They are also called rain or atmospheric. Effluent of this type is a liquid formed on roofs, roads, terraces, squares during precipitation. Stormwater treatment plants usually include several stages and are capable of removing various types of impurities from the liquid (organic and mineral, soluble and insoluble, liquid, solid and colloidal). Stormwater runoff is the least hazardous and least polluted of all.

Types of treatment facilities

In order to understand what blocks a treatment complex can consist of, one should know the main types of wastewater treatment plants.

These include:

• mechanical structures,
• biological treatment plants,
• oxygen-saturating plants that enrich the already purified liquid,
• adsorption filters,
• ion exchange blocks,
• electrochemical installations,
• physical and chemical treatment equipment,
• disinfection facilities.

Wastewater treatment equipment can also include structures and tanks for storage and storage, as well as for the treatment of filtered sludge.

The principle of operation of the wastewater treatment complex

In the complex, a scheme of wastewater treatment facilities with ground or underground execution can be implemented.
Treatment facilities for domestic wastewater are installed in cottage settlements, as well as in small settlements (150-30,000 people), at enterprises, in district centers, etc.

If the complex is installed on the surface of the earth, it has a modular design. In order to minimize damage, reduce costs and labor costs for the repair of underground structures, their hulls are made of materials whose strength allows them to withstand the pressure of soil and groundwater. Among other things, such materials are durable (up to 50 years of service).

To understand the principle of operation of wastewater treatment plants, consider how the individual stages of the complex function.

mechanical cleaning

This stage includes the following types of structures:

• primary clarifiers,
• sand traps,
• trash screens, etc.

All these devices are designed to eliminate suspensions, large and small insoluble impurities. The largest inclusions are retained by the grate and fall into a special removable container. The so-called sand traps have a limited capacity, therefore, with an intensity of effluent supply to the treatment plant of more than 100 cubic meters. m. per day, it is advisable to install two devices in parallel. In this case, their efficiency will be optimal, sand traps will be able to retain up to 60% of suspended matter. The retained sand with water (sand slurry) is discharged to sand platforms or to a sand bunker.

Biological treatment

After removing the bulk of insoluble impurities (clarification of wastewater), the liquid for further treatment enters the aerotank - a complex multifunctional device with extended aeration. Aerotanks will be divided into sections of aerobic and anaerobic treatment, due to which, simultaneously with the splitting of biological (organic) impurities, phosphates and nitrates are removed from the liquid. This significantly increases the efficiency of the second stage of the treatment complex. Active biomass released from wastewater is retained in special blocks loaded with polymeric material. Such blocks are placed in the aeration zone.

After the aeration tank, the sludge mass passes into the secondary settling tank, where it separates into activated sludge and treated effluents.

Post-treatment

Post-treatment of wastewater is carried out on self-cleaning sand filters or using modern membrane filters. At this stage, the amount of suspended solids present in the water is reduced to 3 mg/l.

Disinfection

Disinfection of treated effluents is carried out by treating the liquid with ultraviolet light. To improve the efficiency of this stage, biological wastewater treatment plants are equipped with additional blower equipment.

Effluent that has passed all stages of the treatment complex is safe for environment and may be discharged into the water.

Design of treatment systems

Industrial wastewater treatment facilities are designed taking into account the following factors:

• occurrence level ground water,
• design, geometry, location of the supply manifold,
• completeness of the system (type and number of blocks determined in advance on the basis of biochemical analysis of wastewater or their predicted composition),
• location of compressor units,
• the availability of a free entrance for vehicles that will carry out the removal of garbage trapped by gratings, as well as for sewage equipment,
• possible placement of the outlet of the purified liquid,
• the need to use additional equipment(determined by the presence of specific impurities and other individual characteristics of the object).

Important: Surface wastewater treatment plants should only be designed by companies or organizations that have a SRO certificate.

Installation of installations

The correct installation of treatment facilities and the absence of errors at this stage largely determine the durability of the complexes and their efficiency, as well as uninterrupted operation - one of the most important indicators.

Installation work includes the following steps:

• development of installation schemes,
• inspection of the site and determination of its readiness for installation,
• construction works,
• connection of installations to communications and their interconnection,
• commissioning, adjustment and adjustment of automation,
• delivery of the object.

The full range of installation works (the list of necessary operations, the scope of work, the time required for their implementation and other parameters) are determined based on the characteristics of the object: its productivity, completeness), as well as taking into account the characteristics of the installation site (type of relief, soil, location of groundwater and etc.).

Maintenance of treatment facilities

Timely and professional maintenance of wastewater treatment plants ensures the efficiency of the equipment. Therefore, such work should be carried out by specialists.

The scope of work includes:

• removal of delayed insoluble inclusions (large debris, sand),
• determination of the amount of sludge formed,
• oxygen content check,
• control of work on chemical and microbiological indicators,
• checking the functioning of all elements.

The most important stage in the maintenance of local treatment facilities is the control of work and the prevention of electrical equipment. Typically blowers and transfer pumps fall into this category. Installations of ultraviolet disinfecting radiation also need similar maintenance.

Sewer treatment facilities OS, KOS, BOS.

One of the main ways to protect the natural environment from pollution is to prevent the ingress of untreated water and other harmful components into water bodies. Modern treatment facilities are a set of engineering and technical solutions for sequential filtration and disinfection of polluted effluents with a view to their reuse in production or for discharge into natural water bodies. For this, a number of methods and technologies have been developed, which will be discussed below.

More about wastewater treatment technology

Since centralized sewerage systems are not laid in all places, and some industrial enterprises require preliminary preparation of wastewater, today local sewer facilities are very often equipped. They are also in demand in private houses, suburban cottage towns and detached residential complexes, industrial enterprises, workshops.

Wastewater differs in the source of pollution: household, industrial and surface (occurring from atmospheric precipitation). Household drains are called household fecal. They consist of contaminated water removed from showers, toilets, kitchens, canteens and hospitals. The main pollutants are physiological and household waste.

Industrial effluents include water masses that were formed during:

• performance of various production and technological operations;
• washing of raw materials and finished products;
• equipment cooling.

This variety also includes water pumped out of the bowels during the extraction of minerals. Industrial waste is the main source of pollution here. They may contain toxic, potentially hazardous substances, as well as waste that can be recovered and used as secondary raw materials.

Surface (atmospheric) effluents most often contain only mineral contaminants, and minimal requirements are imposed on their purification. In addition, wastewater is classified according to the concentration of various pollutants. These characteristics influence the choice of method and number of purification steps. To determine the composition of the equipment, the need for construction, as well as the capacity of various types of structures, a calculation is made of the production of wastewater treatment.

Basic cleaning steps

At the first stage, mechanical wastewater treatment is performed, the purpose of which is filtration from various insoluble impurities. For this, special self-cleaning grids and sieves are used. The retained waste, together with other sludge, is sent for further processing or taken to landfills along with municipal solid waste.

In the sand trap, small particles of sand, slag and other similar mineral elements precipitate under the influence of gravity. In this case, the filtered composition is suitable for further use after processing. The remaining undissolved substances are reliably retained in special settling tanks and septic tanks, and fats and oil products are extracted using grease traps, oil traps and flotators. At the mechanical treatment stage, up to three quarters of mineral contaminants are removed from waste streams. This ensures the uniformity of the liquid supply to the next stages of processing.

After that, biological cleaning methods are used, performed with the help of microorganisms and protozoa. The first structure where water enters at the biological stage is special primary settling tanks, in which suspended organic matter settles. At the same time, another type of settling tanks is used, in which activated sludge is removed from the bottom. Biological treatment allows you to remove more than 90% of organic contaminants.

At the physico-chemical stage, the dissolved impurities are removed. This is done using special techniques and reagents. It uses coagulation, filtration, and settling. Along with them, various additional processing technologies are used, including: hyperfiltration, sorption, ion exchange, removal of nitrogen-containing substances and phosphates.

The last stage of treatment is chlorine disinfection of the liquid from the remaining bacterial contaminants. The diagram below shows in detail all the stages described, indicating the equipment used in each stage. It is important to note that treatment methods for various industrial enterprises differ depending on the presence of certain pollutants in wastewater.

Features and requirements for the arrangement of treatment facilities

Domestic sewage is classified as monotonous in composition, since the concentration of pollutants depends only on the volume of water consumed by residents. They contain insoluble impurities, emulsions, foams and suspensions, various colloidal particles, and other elements. Their main part is mineral and soluble substances. For the treatment of domestic wastewater, a basic set of treatment facilities is used, the principle of operation of which is described above.

In general, domestic sewers are considered simpler, since they are built to treat wastewater from one or more private houses and outbuildings. They do not require relatively high performance. For this purpose, specially designed installations are used that provide biological wastewater treatment.

Thanks to them, in suburban housing it became possible not only to equip a shower room, bathroom or toilet, but also to connect various household appliances. Typically, such installations are easy to install and operate, do not require additional components.

For industrial effluents, the composition and degree of pollution vary depending on the nature of the production, as well as options for using water to provide the technological process. In production food products wastewater is characterized by high pollution organic matter Therefore, the main method of purification of such waters is biological. The best option can be called the use of an aerobic and anaerobic method or a combination of both.

In other industries, the main problem is the treatment of oil and fat-containing effluents. For such enterprises, special oil separators or grease traps are used. But the most safe for the environment are water-circulation systems for the purification of polluted water. Such local treatment complexes are installed at car washes, as well as at manufacturing enterprises. They allow you to organize a closed cycle of water use without its discharge into external water bodies.

Special systems and methods are used to determine the method of organizing cleaning and choosing a specific facility (there are many enterprises, so the process must be individualized). Equally important is the price of equipment and work on its installation. Only experts will help you choose the best option for each case.

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