Human life is inextricably linked with water. Therefore, during the construction of housing, one of the first concerns is the construction of a water supply system. But if water is supplied to the house, then you need to take care of drainage. Wastewater treatment systems must be used to recycle used water and to keep soil and water clean. Consider what installations can be used when equipping a sewage system in a private house.

Today, few people are satisfied with the prospect of living in a house devoid of amenities, even if it is just a summer residence. Most owners strive to make their home as comfortable as possible: they organize heating, conduct water into the house.

But if there is a water supply system, then sewerage is also needed - a system for draining and processing wastewater. Since not all suburban settlements have a centralized system for collecting and processing domestic wastewater, a local wastewater treatment system is being built.

Wastewater treatment methods

To clean domestic sewage, the following cleaning methods are usually used:

• Mechanical - sedimentation, filtration.
• Biological - processing of effluents by microorganisms.

There are two types of bacteria in nature that can effectively purify wastewater:

• Anaerobes are microorganisms that carry out their vital functions without oxygen.
• Aerobes are bacteria that do not "work" in an oxygen-free environment.

As practice shows, it is possible to achieve the greatest effect in wastewater treatment if a combination of several treatment methods is used. The modern treatment system provides for the initial settling of wastewater, and then their biological treatment using anaerobes and aerobes.

Anaerobic septic tanks

A septic tank is an installation in which wastewater passes through several stage-wise stages of purification. The principle of operation of the septic tank is to settle wastewater and the processing of organic impurities by anaerobic bacteria. To achieve the best cleaning quality, septic tanks are made multi-chamber. The main part of solid waste settles in the first chamber, and pre-purified water flows into the subsequent ones.

Organic impurities, which make up the majority of domestic sewage pollution, are decomposed by anaerobic bacteria. Organic matter decomposes into simple components - methane and water, and insoluble residues settle to the bottom of the chambers.

The treatment of effluent with aerobic bacteria begins after it leaves the septic tank and enters the aeration fields - devices necessary for post-treatment of effluents. In aeration fields, wastewater is additionally filtered by passing through a sand and gravel filter. Thus, after going through all the stages, the water is almost 100% purified and does not harm the environment.

Purification steps in an anaerobic septic tank

• Stage one. It is carried out in the primary settling tank. This is where a process takes place, which is commonly called effluent clarification. In the first chamber, the contaminated water is separated by specific gravity. Particles with a heavy weight settle to the bottom, inclusions that are lighter than water rise to the top. In the center of the primary sump, where the overflow pipe to the second chamber is located, clarified wastewater is collected. The sedimentation continues in the second chamber, only here the deposition of smaller inclusions, which are in suspension in the liquid, is already taking place.

Advice! The septic tanks are built in such a way that the effluent from the chamber to the chamber flows slowly. Only at a low speed of movement is it possible to ensure high-quality sedimentation.

• The second stage is biological. The organic matter settled to the bottom is biologically processed by anaerobic bacteria. In the process of fermentation of the sediment, heat is released, therefore, the temperature in the septic tank is always elevated. This circumstance makes it possible to use septic tanks not only in summer, but also in winter.

• The last stage of cleaning takes place on the filtration fields. The sewage, clarified in a septic tank, is fed here through pipes. Holes are made in the pipes through which water seeps into the soil filter. Passing through a layer of sand and gravel, the water is filtered. In addition, it is additionally purified with the help of aerobes that live in the soil.

Aerobic septic tank

In addition to traditional septic tanks, modern systems of biological wastewater treatment - VOCs, additionally equipped with aerators, are widely used today. In such stations, wastewater is alternately processed by anaerobic and aerobic bacteria, as a result, at the outlet of the treatment plant, the water is 98% purified, so there is no need to build filtration fields.

Water purified in VOCs can be discharged onto the ground or into a nearby body of water without harm to the environment. If necessary, the water can be directed to a storage well for household use, for example, for watering lawns or a garden.

Stages of wastewater treatment in aerobic septic tanks

• Stage one - upholding. Just like conventional septic tanks, VOCs use such a simple but reliable mechanical cleaning method.
• Stage two - the processing of the sediment by anaerobic bacteria. The organic matter precipitated as a sediment is processed by anaerobic bacteria. That is, until this moment, there are no differences in the operation of a simple septic tank and VOCs.
• Stage three - processing with aerobic bacteria. When the aerator is turned on in the chamber, the stage of aerobic cleaning begins. In an oxygenated environment, bacteria efficiently and quickly recycle most of the organic matter.

• Stage four - defending again. After aerobic treatment of wastewater, water enters the secondary settling tank, where the precipitation of insoluble sediment - sludge occurs. The purified water flows to the outlet, and the activated sludge is used again in the purification process. As excess sludge accumulates, it will need to be removed from the sump.

Simple septic tank or VOC?

What kind of wastewater treatment system should be preferred when building a local sewage system? There is no definite answer to this question. Local conditions will need to be taken into account when selecting an installation. Let's conduct a small comparative analysis of septic tanks and VOCs:

• Space required for installation. For the installation of a modern VOC, as a rule, one or two square meters of area is sufficient. If you need to install a septic tank, then a large area will be required. The septic tank itself is somewhat larger than VOCs, but the main area will be required for the construction of filtration fields necessary for additional wastewater treatment.
• Geological characteristics of the site. If it is decided to install a VOC, then the geological characteristics of the site can only affect the choice of the VOC modification. But the arrangement of filtration fields on clayey soils is a difficult task.

Advice! If there is a high soil water on the site, then you should purchase a VOC with forced drainage, that is, equipped with an additional pump.

• Autonomy. If the septic tank is a completely autonomous installation, then the VOC requires power supply for operation.

Advice! If the local sewerage system is equipped with a volatile waste biological treatment plant, then during a power outage it is necessary to reduce the use of water to a minimum. Otherwise, overflow of the chambers may occur, since the pumps that transfer the wastewater do not work.

• Service. Both conventional septic tanks and VOCs require regular maintenance. The septic tank will have to be cleaned from the accumulated sediment approximately 1-2 times a year with the help of sewage equipment. Cleaning the sludge receiver in VOCs needs to be done more often - about once a quarter, but this work can be easily done on your own.

Advice! When choosing a place to install a septic tank, you need to take into account the need to clean it and leave free passage for the sewer machine.

• Price. A conventional septic tank is cheaper than VOCs. However, it is necessary to take into account the cost of constructing filtration fields, as well as the fact that filtration fields last no more than 10-12 years, after which they need to be changed.

Design

Having decided on the type of treatment plant, you can start designing drainage systems for a country house. Most often, the project is drawn up simultaneously with the project of the house. But if a building that has already been put into operation is being improved, then a sewerage project for a private house is drawn up separately.

Local conditions must be taken into account when designing a wastewater disposal system. Therefore, before starting the design work, it is recommended to carry out geological exploration, during which the following points will be clarified:

• features of the site relief;
• characteristics of the soil, in order to select the method of water drainage, it is necessary to assess the absorbency of the soil;
• level of location and seasonal rise of groundwater.

Before the development of a project for a drainage system for a house begins, the following points need to be clarified:

• average daily water consumption in the house;
• frequency of use - year-round or periodically.

After collecting information, you can start drawing up a project.

Tilt angle

An important point is the angle of inclination of the pipeline. This point is important in the construction of gravity systems. If it is impossible to comply with the required angle of inclination, it is necessary to plan the construction of a pressure system in which the wastewater is pumped using a fecal pump.

Many home craftsmen who undertake independent installation underestimate this point, and meanwhile, mistakes in both directions reduce the efficiency of the system.

If the angle is not large enough, then the flow will move through the pipeline at a low speed. In this case, some of the large inclusions will have time to precipitate in the pipes, and this is fraught with the formation of blockages. Too large an angle will also interfere with the normal movement of the transported medium. Water will drain excessively quickly, not having time to carry away heavy inclusions that will linger in the pipes, forming blockages.

The optimal angle of inclination depends on the diameter of the pipe that is used to create the pipeline. The smaller the diameter, the larger the draft angle should be. So, if pipes with a diameter of 50 mm are selected, then a slope of 3 cm per meter should be observed. When using 100 mm pipes, the slope should be 2 cm.

System elements

When creating a project, a diagram of internal and external networks is created. The internal networks include all the elements that are located in the house, these are:

• a riser connected to a fan pipe leading to the roof;
• plumbing elements (sinks, bathtubs, toilets, etc.);
• pipes connecting plumbing elements with a riser.

The boundary dividing the internal and external networks is the pipe outlet through the foundation. External networks include:

• pipeline connecting the outlet with the treatment plant;
• inspection wells for network maintenance;
• treatment plant.

When constructing a local sewage system, one cannot do without a local treatment plant. Depending on local conditions and the capabilities of the owners, this can be a simple anaerobic septic tank or a modern local biological treatment plant.

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Sewerage and wastewater treatment in a private country house

Country houses located in dacha associations, rural areas and even in a number of cottage villages do not always have the ability to connect to a centralized sewer network. The optimal solution to the problem is the use of a local treatment plant - VOC.

From the cesspool to the VOC

Modern technologies in the field of engineering equipment are striding by leaps and bounds, and today many types of installations for the treatment of domestic wastewater have been developed. Let's remember how the history of private sewerage developed.

First - a cesspool, then its modernized version - a septic tank and finally installations in which a full cycle of wastewater treatment is carried out. The latter are called differently: stations (systems) of deep biological treatment, wastewater treatment plants (WWTP), local treatment facilities (VOC), etc.

In order not to get confused in these names, which in fact mean the same thing, we will use the abbreviation VOC.

But we will talk about VOCs a little later, and now we will discuss the question: are septic tanks already the past or not yet?

Since a consumer, inexperienced in the problems of private sewage, sometimes misinterprets the meaning of this term, it will not be superfluous to recall that an industrial septic tank is a large container (most often made of plastic) located in the ground and connected by a supply pipe with a sewer outlet from the house.

The simplest septic tank is essentially a large barrel, more complex models are divided into two or three sections or consist of two or three separate containers. In a septic tank, drains do not just accumulate, they are initially decomposed into heavy ones, gradually settling down, and light ones, floating to the surface. Thanks to this method of treatment, which is called mechanical, the effluent is purified by 60%, which is a very low degree of purification, and therefore it is forbidden to dump them on the relief.

Technologies of ten years ago assumed the device on the area of ​​filtration fields adjacent to the house - drainage systems, along which soil additional treatment of wastewater from the septic tank took place. Today it is already an outdated method. However, the septic tank itself cannot be discounted. Sometimes he helps to solve certain problems. For example, if we are not talking about a country house for year-round living, but about a summer residence, where the family visits seasonally or periodically. Since the septic tank is suitable for processing a relatively small volume (1-3 m 3 / dry) of domestic wastewater and fecal matter, you will have to call a sewer truck from time to time. To reduce the rate of filling the container, the drains can be divided into "gray" (water after washing dishes, bathing, washing) and "black" (coming from the toilet) and sent to the septic tank only "black".

In any case, a septic tank will be the most economical solution for a periodical home. Sometimes it has to be installed for other reasons. For example, in water protection zones, where it is forbidden to use even VOCs, cleaning effluents by 94-98%. Actually, this is all the information that a private developer needs to know about a septic tank in order to make a choice in favor of a septic tank or VOC.

Wastewater disposal options

a) Discharge of treated water by gravity into the existing drainage network
b) Drainage of effluents into an intermediate well, in which a drainage pump is installed
c) Pressure discharge of effluents into a road ditch
d) Gravity drainage of wastewater into a filter (drainage) well

How aeration VOCs work

There is a great variety of individual sewage systems on the Russian market. Some of them, with different names, are in fact almost "twins". Therefore, it makes no sense to describe each model separately and compare them. It is much more important for the future user to understand the fundamental design difference between the systems from each other.

Conventionally, all installations can be divided into two types: aeration and complex. In the first, wastewater treatment occurs due to the work of aerobic bacteria, which use oxygen contained in the air for their life. How does it enter the VOC container? Aeration (saturation of water with oxygen in the air) is compulsory: for this, compressors (pneumatic aeration) or pumps (ejector aeration) connected to the installation are used.

The wastewater treatment method used in such equipment is biological, therefore this type of VOC is also called biological treatment systems (less often - bioseptics). Structurally, the device is a container (usually made of polypropylene) with technological hatches, divided by partitions into several sections: septic tank, anaerobic bioreactor, stage I aeration tank - biofilter, sedimentation tank, stage II aeration tank, secondary sedimentation tank - contact tank, pump compartment. The number of compartments may vary from model to model.

Their common purpose is to consistently purify domestic wastewater to the parameters specified in the technical data sheet. This is done as follows. Wastewater is sent to a septic tank, where it is fermented, suspended solids are separated, sand and other insoluble impurities are settled. After that, the partially clarified wastewater enters the anaerobic bioreactor, where it is purified with anaerobic sludge (a community of microorganisms). The process takes place without oxygen. Anaerobic bacteria convert difficult-to-oxidize organic compounds into easily oxidizable ones. Then comes the turn of cleaning in a stage I aeration tank with the effect of oxygen (using forced aeration). Here wastewater is mixed with activated sludge, which absorbs and oxidizes pollution. After that, the waste water enters the aeration tank of the II stage, where it is further purified (by oxidation and adsorption) with biofilm from microorganisms formed on the load of artificial "algae" with continuous fine-bubble aeration. Further, in the secondary sedimentation tank, activated sludge is deposited and returned to the septic tank with the help of an airlift, and wastewater purified to 98% is discharged to a low relief location. This is how VOCs of the first type work - aeration ones.

Integrated wastewater treatment plants in a private house

VOCs of the second type are complex installations in which wastewater treatment occurs in three ways: mechanical, biological and chemical-physical (coagulation). Structurally, they differ significantly from aeration plants. Complex VOCs consist of a vertical settler with partitions (septic tank) and a bioreactor located above it. In the septic tank, sediment settling and anaerobic purification takes place. In the bioreactor, aerobic (with oxygen) purification of already clarified effluents. Bacteria attach to the biofuel of the reactor, forming an active biofilm. The set of installations includes a precipitating chemical (coagulant) in the form of tablets. It binds phosphorus, significantly reduces its concentration in effluents and accelerates the precipitation process. The coagulant is in a plastic container that is hung on the toilet bowl. With each flush, particles of the substance enter the system along with the drains.

What does the consumer need to know?

Aeration VOCs do not allow salvo discharge of effluents (more than 100 l / h). For example, if there are frequent guests in the house, the consumption of wastewater (taking a bath, shower, etc.) increases sharply, due to which the colony of bacteria, with the help of which the cleaning is carried out, is partially (or completely) washed out. Consequently, for some time after the salvo discharge, the installation will not be able to clean the effluents up to the indicators specified in the passport. A prolonged power outage also negatively affects the operation of the first type of systems, namely, leads to the partial or complete death of the bacterial colony. True, some manufacturers "forget" to notify the buyer about this. Others argue that this is not a significant drawback of the devices, because one has only to put the bacteria purchased in the store for septic tanks into the container, and the installation will begin to function in the same mode. This is true, but in this case, the exit to the degree of wastewater treatment declared by the manufacturer will occur no earlier than in two to three weeks.

But for complex VOCs, neither a salvo discharge, nor a power outage does not threaten negative consequences. The reason for this is in the structural differences between the installations of the first and second types. The fact is that in aeration VOCs, aerobic and anaerobic processes occur in one volume, where, due to aeration, the activated sludge is constantly mixed. In complex VOCs, sedimentation of sludge occurs in a separate chamber, where it is in a state of relative dormancy, and since bacteria in such systems live not only in water, but also in a bioreactor, they are not threatened with washing out by non-standardized drains, as well as death due to shutdown electricity. Even with a long power outage, bacteria on the biofilter are alive for three months. The exit to the operating mode declared by the manufacturer occurs 4-10 days after the start of the installation.

Household waste (toilet paper, hygiene items) should not enter the aeration units, as this can lead to blockage of the pumps that ensure the operation of the station. In addition, it is not desirable to drain there chemical household detergents that worsen the conditions necessary for the vital activity of bacteria. But complex installations are more "loyal" to these factors, mainly due to their design features. Household waste trapped in them (toilet paper, napkins, food debris, pet hair, polymer films) remains in the settling chamber and cannot enter the section where the pumps are located. A small amount of chlorine-containing preparations (washing powder, bleaches), which along with water entered the VOC of the second type, will also not lead to a loss of system performance.

Both types of devices are volatile - the compressor (pump) must operate continuously. However, complex VOCs have a slightly lower power consumption due to the fact that they use not a compressor, but a pump that operates on a timer (15 min. / On - 15 min. / Off).

Systems of varying complexity of both domestic and foreign manufacturers are presented on the Russian market. In some of them, the cleaning process is controlled by a programmable controller that changes the operating mode of the installation based on the amount of incoming wastewater. If there are few of them, the controller switches the system to the economy mode, with salvo discharges - to the forced mode. Although automation simplifies the operation of the system, it significantly increases the cost of VOC and its further maintenance.

Where to take drains in a country house

When installing equipment, one of the main questions is where the water purified in the installation goes. The easiest option is to drain it by gravity. After cleaning in VOC, wastewater is discharged directly onto the terrain or into a drainage network (trench, roadside ditch) with a depth of at least 80-90 cm, protected from flooding by floods. The second option is a filter well, used in cases where gravity drainage is impossible.

From the VOC, at a distance determined by the project, a reinforced concrete well with a depth of about 3 m is made. On the bottom of which rubble is poured (in order to increase the productivity of the system). The throughput of the well depends on the type of soil.

In sandy soils, it is 80 l / day. per 1 mg of the area of ​​the outer surface of the filtering cylinder of the well, in sandy loam - 40 l / day. In clay soils or with high groundwater levels, this scheme does not work. In these cases, drainage pumps are used. To pump out purified water from VOCs, submersible devices with a nominal bore (maximum size of impurities) of 10-12 mm are used. The pump can be installed directly in the last VOC chamber or in an additional intermediate well, it must be sealed. This is to prevent the pump from pumping ground water as well.

When installing a wastewater treatment system, it is important to take into account that it should be located at a distance of 3-5 m from the cottage so that in winter the sewage coming from the house does not freeze on the way to the VOC

Prices

Manufacturers indicate the cost of installations in different ways. Some name the price only for the equipment itself, others - for the "turnkey" system, that is, taking into account the installation.

When choosing devices for sewage treatment, it is better to focus on a full range of services. On average, VOC + delivery to the customer's site + installation will cost from 80,000 rubles. (installation volume is designed for four users) up to 140,000 rubles. (for ten users).

For some systems, monthly service activities may be required, the cost of which sometimes reaches 20% of the price of the equipment per year.

The general rule for all installations is to clean the settling chamber on average once a year from the accumulated excess sludge using a sewage machine. The cost of sewer services is 750-800 rubles / m 3.

How much wastewater plant to choose

The choice of a household wastewater treatment plant for a specific construction environment is a complex multifactorial task. First of all, it is necessary to calculate the performance of the equipment, since the dimensions of the container depend on this.

The specific drainage rate (according to SNiP 2.04.01 -85) ranges from 200 to 300 liters per person per day and includes the use of a toilet, bath, shower, kitchen sink and washing machine. A family of three or four people, on average, spends 200 liters of water per day on washing, washing dishes and washing, another 200 liters for the toilet, and 400 liters for the shower and bath.

In total, it turns out 800 liters. The size of the tank is chosen so that its working volume exceeds the daily rate of water consumption by three to five times. Therefore, in our example, we need a 4 m 3 tank.

Do-it-yourself installation of an aeration station (VOC) - photo

a) Preparation of the pit, subsystem b, c) The installation body is placed in the pit, d, e) Cut-in of underwater and branch lines into the body of the treatment plant f, g) Installation of electrical equipment, filling the installation with water and sprinkling with sand, h) Outer part of the aeration station

SEPTIC, BIOSEPTIC OR BIOLOGICAL CLEANING STATION - CHOOSE FOR A PRIVATE HOUSE?

It used to be more difficult to organize life support by urban standards in rural areas than in space. Fortunately, times have changed, and the issue is being resolved where connection to centralized water supply and sewerage systems is a matter of an unrealistically distant future. It is simply solved locally for one or several households - by drilling an artesian well and choosing an autonomous sewage system.

Which one to prefer - a septic tank, bioseptic tank or biological treatment plant?

All variants of local treatment systems (VOCs) have both advantages and disadvantages. Let's figure it out!

Local principles

First, a little science. It should be understood that any modern device that solves the "toilet" problem (by the way, including a dry closet) works thanks to microorganisms. As a result of the vital activity of these creatures invisible to the eye, biological oxidation processes take place in the effluent. The solid fraction of the waste decomposes, other organic compounds are formed, and the water is settled. Everything is simple, but there is a nuance. Biological oxidation is of two types: aerobic (when the process goes with oxygen access) and anaerobic (without access).

And bacteria are different in these processes. When the aerobic ones get down to business, the degree of purification corresponds to the current hygiene standards; when anaerobic ones work, it does not correspond, and additional treatment is required.

What is a septic tank

In fact, a septic tank is a sewage sump with anaerobic bacteria. Structurally, they are a reservoir - sealed or without a bottom. There are models consisting of non-

how many containers, coupled to each other with branch pipes and overflows. Heavy particles sink to the bottom, the most liquid fraction sequentially flows from chamber to chamber. By settling in this way, the plums are gradually cleared.

Theoretically, the more chambers (tanks) a septic tank has, the better and more reliable it is. But in practice, in complex systems, the risk of breakdown is higher, their operation is more expensive, since many components require periodic maintenance. In addition, as a rule, the largest amount of sediment remains in the first section. So it is not worth unnecessarily complicating the septic tank, three containers are the optimum.

Part of a larger whole

A septic tank is a non-self-sufficient device. Due to anaerobic processes, plums will leave about 65% of the pollution in it. What to do with the still far from ideal state, a foul-smelling moisture? It is drained into a drainage well or taken away through the so-called "filtration field" (a piece of land arranged away from the house in a special way for additional purification of water by filtering it through the soil). Therefore, it is necessary to have this drainage well or a place sufficient for organizing a "filtration field" on your land plot. What to do with sediment accumulating on the bottom of the chambers? It is periodically raked out. Alas, you can't do without a flusher. This means that it is necessary to provide free access for the sewer truck to the septic tank. These points will have to be taken into account when choosing an autonomous sewage system.

"Pros" and "cons" of septic tanks

Maintaining performance after long interruptions in use.

Some models do not require an electrical connection.

Low degree of wastewater treatment - up to 65%.

Unpleasant odors are possible in the vicinity of the unit.

The installation requires a significant amount of space on the site.

Access roads are required for service.

Complex installation of bulky and heavy equipment.

A septic tank is not the best solution if the groundwater level is high and if the site is clayey.

What is bioseptic

This is a type of septic tank in which the cleaning process is enhanced by the regular loading of bacterial preparations.

Its design includes a biofilter - a small reservoir with a chemically inert, rot-resistant backfill. It can be, for example, foam balls, shungizite, expanded clay or shell rock. The backfill is an excellent medium for the growth of bacterial colonies and at the same time plays the role of a mechanical filter - it retains solid fragments of sewer drains. The degree of purification in bioseptics is slightly higher than in conventional ones, and less sediment is formed at the bottom of the chambers. That is, all other things being equal, the sewer will have to be called less often.

What is aeration tank

In fact, initially, the aeration tank was called a reservoir in which the treated wastewater is mixed with activated sludge - a biocenosis of microorganisms capable of absorbing organic matter. Today, an aerotank is often called a deep biological treatment plant, which includes this reservoir. A kind of bioseptic? Probably you can say so. But, definitely, the difference between an aeration tank and a septic tank with a biofilter is fundamental: other bacteria, aerobic, are used here.

The system is based on biological oxidation with air admission, which is forced by the compressor. Due to aeration, the oxidation process occurs evenly throughout the volume. The “end product” - odorless sludge - is fed into a special compartment. Filtered water does not need additional treatment!

ON A NOTE

Any VOC is designed for a certain number of users. To calculate the volume of the treatment plant, it is recommended to proceed from 200 l / day per person. The volume of simultaneous discharge of effluents (“salvo discharge”) is also important. This indicator can greatly affect the quality of cleaning. The greater the throughput of VOCs per day, the more reserve must be available for the simultaneous reception of discharges from various plumbing units for an hour.

"Pros" and "cons" of the aerotank

High degree of wastewater treatment - odorless product at the outlet.

Possibility of installation in a ventilated basement. The aeration tank does not have to be buried in the ground, like a septic tank (a fan riser is required!).

Saves space on the site - "filtration field" is not needed.

In winter, an aeration tank is more efficient than a septic tank (aerobic processes occur with the release of heat, anaerobic - with absorption).

Many people, using purified water, do not even suspect by what methods this is achieved. Nevertheless, now there are a number of cleaning methods, such as: mechanical, biological, biochemical. chemical, physico-chemical, which, in turn, are subdivided into types. In some cases, these methods are applied in a complex manner. Which of them is the most effective - this will be discussed below.

Purification of water from various kinds of impurities, heavy metals and their compounds present in it is a painstaking technological process. Now there are many methods of obtaining a clean liquid, methods of wastewater treatment differ in terms of the degree of pollution and the concentration of impurities in the water.

Why clean drains?

The main purpose of purification is the destruction of contaminants of various nature and their removal. This is a complex production process, the finished product of which is. Its parameters have been brought up to the established standards. Moreover, the requirements for water for various purposes differ significantly and are steadily increasing.

Cleaning methods

The choice of cleaning method depends on the type of dirt. Most often, maximum filtration is achieved by combining different methods.

Of the whole variety of existing methods, the main types can be distinguished:

1. Mechanical - wastewater treatment is carried out from insoluble impurities.
2. Chemical. At this stage, the neutralization of acids and alkalis takes place.
3. Biochemical. Together with chemical reagents, microorganisms are used that consume contaminants as food.
4. Biological. Water treatment takes place without the use of chemicals.
5. Physicochemical wastewater treatment includes several types, each of which will be discussed below.

Mechanical

They are used for preliminary purification of effluents from insoluble contaminants and are used in combination with other types. The cleaning itself is carried out in several stages.

Cleansing

In the process of settling, particles with a specific gravity greater than that of water settle to the bottom, and with a smaller one - rise to the surface. The lungs include oils, oil, fats, resins. Similar impurities are present in industrial effluents. Subsequently, they are removed from the treatment facilities and sent for processing.

Important! To separate natural solid suspensions, they use a special version of sedimentation tanks - sand traps, which are tubular, static or dynamic.

Straining and filtering

Grilles are used to separate coarse dirt in the form of paper, rags, etc. To capture small particles during water purification, fabric, porous or fine-grained filters are used. For the same purpose, micro-strainers are used, consisting of a drum equipped with a mesh. The separated substances are washed out into the trapping hopper under the influence of water, which is supplied through the nozzles.

Biochemical

The wastewater treatment system, which uses special microorganisms in the process of working with chemicals, is of two types:

The first ones carry out water purification in natural conditions. These can be reservoirs, irrigation fields where additional soil cleaning is required. They are characterized by low efficiency, high dependence on climate conditions, and large areas are required.

The latter function in an artificial environment where favorable conditions are created for microorganisms. This significantly improves the quality of cleaning. Such stations can be divided into three types: aerotanks, bio- and aerofilters.

1. Aeration tanks. Productive biomass is activated sludge. With the help of special mechanisms, it is mixed with the delivered wastewater into a single mass.
2. A biofilter is a device where a filter bed is provided. For it, materials such as slag, expanded clay gravel are used.
3. The air filter is built according to the same principle, but air is forced into the filtering layer.

Biological

Biological wastewater treatment methods are used when there is organic pollution. A greater effect is observed when using aerobic bacteria. But to ensure their vital activity, oxygen is required. Therefore, when working under artificial conditions, air injection is necessary, which leads to an increase in costs.

The use of anaerobic microorganisms reduces costs, but is inferior in efficiency. To increase the quality of filtration, the previously processed wastewater is purified. Most often for this purpose, contact clarifiers are used, which are a multilayer filter. Less commonly, microfilters.

Purification of waste water by this method relieves them of toxic impurities, but at the same time there is a saturation with phosphorus and nitrogen. The discharge of such water will disrupt the ecological system of the reservoir. Nitrogen removal is carried out in other ways.

Physicochemical

This method of purification allows the separation of finely dispersed and dissolved mixtures of inorganic compounds from the effluents and the destruction of difficult-to-oxidize organic substances. There are several types of such cleaning, the choice of which depends on the volume of water and the amount of impurities it contains.

Coagulation

This type involves the introduction of chemical reagents: ammonium salts, iron, etc. Harmful impurities settle in the form of flakes, after which their removal is not difficult. During coagulation, small particles stick together into large compounds, which significantly increases the efficiency of the deposition process. This method of purification separates the bulk of unwanted impurities from the effluent. It finds application in the construction of industrial treatment systems.

Flocculation

To accelerate the process, in which the formation of sediment occurs, flocculation is additionally used. Molecular compounds of the flocculant, upon contact with harmful impurities, are combined into one system, which makes it possible to reduce the amount of coagulant. The flakes that have precipitated are removed mechanically.

Flocculants are of various origins: natural (silicon dioxide) and synthetic (polyacrylamide). The speed of the flocculation process is influenced by the order of addition of reagents, the temperature and level of water pollution, with what frequency and force the mixing takes place. The residence time of the effluents in the mixer is 2 minutes, and the contact with the reagents is up to one hour. After that, water is clarified in the sedimentation tanks. Reducing the cost of coagulants and flocculants allows double treatment of wastewater, when the initial settling is carried out without the use of reagents.

Adsorption

Important! There are a number of substances that are capable of absorbing harmful impurities. The adsorption method is based on this. Activated carbon, montmorillonite, peat, and aluminosilicates are used as reagents.

Wastewater treatment in this way gives high efficiency, allows you to remove various types of contaminants. There are two types of adsorption: regenerative and destructive.

The first option is due to the removal of harmful impurities from the reagent and only after that they are utilized. In the second, they are destroyed simultaneously with the adsorbent.

Extractive

Harmful impurities are placed in a mixture consisting of two liquids that do not dissolve in one another. It is used when it is necessary to remove organic substances from the effluent.

The method is based on the addition of a certain volume of extractant. In this case, harmful substances leave water and are concentrated in the created layer. When their content reaches its maximum value, the extract is removed.

Ion exchange method

Due to the exchange that takes place between the contacting phases, it is possible to remove radioactive elements: lead, arsenic, mercury compounds, etc. With a high content of toxic substances, this method is especially effective.

Chemical

All chemical wastewater treatment methods are based on the addition of reagents that convert dissolved substances into a suspended state. After that, they are removed without any difficulty.

The following are used as reagents:

• oxidizing agents (ozone, chlorine);
• alkalis (soda, lime);
• acid.

Neutralization

Wastewater treatment in a similar way neutralizes pathogenic bacteria, brings the pH level to the required standard (6.5-8.5). For this, the following methods are used:

• mix alkalis and acids in the form of liquids;
• chemical reagents are introduced;
• filter wastewater containing acids;
• gases are neutralized with alkalis and acid - with ammonia solution.

Oxidation

When it was not possible to remove impurities mechanically and by settling, oxidation is used. In this case, ozone, potassium dichromate, chlorine, pyrolusite, etc. act as reagents. Ozone is rarely used because of the high cost of the process and is explosive at high concentrations.

Recovery process

Important! The essence of the method: the physical state of all harmful contaminants is restored, and then they are removed by flotation, settling or filtration.

When it is necessary to purify arsenic, mercury, chromium, use this method.

Flotation

Flotation method - high pressure air cleaning

This is a method in which the floating of debris to the surface is achieved by adding vortex air currents to the wastewater. The effectiveness of the method will depend on the hydrophobicity of the particles. The resistance of air bubbles to destruction is increased by the addition of reagents.

For clarity, the efficiency of wastewater treatment by various methods can be presented in the form of a table.

Recycled sludge, which is the result of domestic wastewater treatment and some industrial sectors, can be used by agriculture as fertilizers.

Alex, 20 May 2017.

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The chemical method of wastewater treatment, as a rule, is used in industrial production, where, as a result of activities, water is polluted by various substances. In order to remove various impurities from polluted water, special reagents are added to it, which help to form hardly soluble substances that precipitate. The chemical method of purification also involves the disinfection of already purified water using chlorine-containing reagents that destroy pathogens.

Mechanical wastewater treatment

Mechanical wastewater treatment helps to remove large debris and particles of mineral origin, which are in the wastewater in an undissolved suspended state. During mechanical treatment, wastewater passes through sand traps, grates and special filters, then it settles in a sump, where it is partially filtered and clarified. This method is applied immediately before biological treatment.

Biological sewage treatment

Biological treatment is designed to free waste water from organic compounds dissolved in it. Special groups of microorganisms take part in this process: aerobes, which develop only when there is oxygen in the waste water, and anaerobes, which require oxygen deficiency. Accordingly, cleaning is aerobic and anaerobic. Modern wastewater treatment plants use a combination of anaerobic and aerobic treatment with remarkable results.

Aerobic treatment takes place in aeration tanks, in septic tanks with a biofilter, in filtration and absorption fields, in filter wells with natural and forced air intake. Forced air flow is created in the treatment plants using compressors. In all other cases, oxygen comes from the ambient air. This chemical element is the main one in the life of aerobic bacteria. In the presence of oxygen, aerobes begin to actively multiply and feed on organic pollutants, as a result of which an intensive purification of effluents occurs. In parallel, the formation of activated sludge in the treated water is observed. Activated sludge is a very useful substance, as it mixes with sewage and causes oxidation of hazardous organic compounds, converting them into simple and harmless components. As a result, the water is freed from bacterial contamination, becomes transparent, and loses the unpleasant smell of sewage.

The advantage of aerobic treatment is the almost complete purification of wastewater from organic matter. Anaerobic cleaning takes place without air access. For this, special closed tanks are made, where oxygen deficiency is created.

Such conditions are favorable for anaerobic bacteria, which are involved in the fermentation and decomposition of organic matter into water, methane, carbon dioxide and other simple compounds. Anaerobic treatment takes place in septic tanks, metatanks and special two-tier sedimentation tanks.

• Heating pipes with a heating cable and other methods of insulation

Wastewater treatment is an irreplaceable process as it makes sewage waste safe for people and the environment. Today, technological progress negatively affects the water resources of our planet, so every drop counts. For this reason, treatment methods have been developed that help reuse wastewater for irrigation of land or simply recharge the soil. In today's article, we will discuss with you the main methods of filtering sewage fluid.

First, let's find out what belongs to the concept of wastewater? For this understanding, it is customary to take all the liquid with and without impurities, which is drained into the sewer system. An important characteristic is the presence of contamination obtained in a particular field of application. It is worth considering that the liquid of atmospheric precipitation is also read in here.

Types of contamination

Wastewater treatment is a process that takes place with the correct selection of equipment. It is worth considering that its important component is compliance with a certain type of pollution. For this reason, let's find out their types that can be found in wastewater:

• Mineral contamination... This type includes all inorganic components, such as: salt, earth, etc.
• Organic matter... It is a sewage fluid containing the remains of the flora and fauna of the world. Their composition usually consists of chemical organics and polymers.
• Biological components... They are represented by bacteria and various other microorganisms.

Attention! In most cases, a sewer drain has all three components. If it is domestic wastewater, then organic matter will treat minerals as 3 to 2. As for bioorganisms, their number depends on the environment.

Cleaning standards

Any water treatment plant must fulfill a certain level of recycling. It is worth noting that the regulated strict rules are prescribed only for the industrial sector. In addition, the ratio of each type of impurity is fixed by law. For example, iron after processing should be present in an amount of no more than 0.1 mg per liter.

In relation to household drains, there are softer requirements. But this is not a reason to relax. One of the most important rules for managing wastewater in a private property is that untreated wastewater cannot enter the environment. For violation of this regulation, the owner of the house will be held administratively liable.

Important! Today, the state regulates only the maximum possible amount of impurities in water. At the moment - this only applies to the discharge into the reservoir. But remember that verification can present these claims in relation to the discharge of runoff into the soil.

Wastewater treatment methods

Based on the variety of filtration and wastewater treatment methods, today they can be divided into types. Namely, there are two types of wastewater treatment methods:

• Destructive species;
• Recuperative methods.

For the former, a characteristic feature is the process of dividing wastewater into simple components, which in the future can be easily discharged, for example, in the form of gas. The second types select all valuable substances from the sewage fluid in order to process them in the future.

The cleaning process - how to do it

Technological progress does not stand still, and therefore every day there are new ideas and ways to clean the drains. After all, do not forget that this is an additional water resource. In this section, we will get acquainted with each of the types separately, but first, let's list them:

• Mechanical;
• Biological;
• Physicochemical;
• Disinfection method;
• Thermal disposal.

Let us consider in detail the methods of wastewater treatment.

Mechanical method

This is one of the simplest options. The process itself includes the removal of all components from the effluent that do not dissolve. What are these components? These primarily include particulate matter and grease. Sewage water is passed through a sieve and a sump, which is then passed only by liquid with small particles.

The best option for mechanical treatment of sewage water is considered to be the membrane method. Its main feature is nothing more than the best cleansing process. The main thing is not to forget that this type of filtration gives a result of 70% and is the start for the biological method.

Biological cleaning process

Wastewater treatment with biological substances is carried out by the functioning of bacteria and microorganisms in the system. Their main feature is the ability to oxidize solid particles. The basis for the creation of this method was the microflora of natural water sources. Studies have shown that wastewater gets rid of nitrogen and phosphorus, which are hazardous to the environment. Bacteria are of the following types:

• Anaerobic microorganisms that can function without air;
• Aerobic types cannot work without oxygen.

If cleaning is carried out with the help of air, that is, with aerobic bacteria, then it is possible to install a biofilter or aeration tank. These structures have a high purification efficiency and can fight activated sludge. With anaerobic microorganisms, a fermentation process takes place, which converts organic matter into methane and carbon dioxide.

With such cleaning, biofilters and aeration tanks with activated sludge are used. They are highly purified and more efficient than biofilters for wastewater treatment. Aeration of water and its deep biological treatment are carried out in aeration tanks. In addition, the result is activated sludge, which is a good fertilizer. Anaerobic wastewater treatment is carried out without oxygen. When exposed to anaerobic bacteria, the process of fermentation and the transformation of organic matter into methane and carbon dioxide occurs. It is worth noting that the second method is slightly cheaper.

Attention! In modern devices, two types of microorganisms are used, which can be easily used even in industrial sewers.

Physicochemical method

These wastewater treatment methods are very effective and are based on the teachings of the sciences of chemistry and physics. These types include:

• Electrolysis is a very popular method in industrial plants. The basis of the treatment process involves the destruction of organic constituents of water to obtain inorganics.
• Coagulation is water purification, which is carried out when components stick together under the action of forces. The result of the process is the formation of an aggregate.
• Precipitation of metal hydroxide flakes- this action is the result of the influence of coagulants, which cause a precipitate to form. The formed flakes are used for wastewater treatment.

The physicochemical process has a large number of advantages, for example, the removal of toxins and impurities that cannot be oxidized. It is also worth adding that this method provides a very high percentage of purification. This method can easily automate the dimensions of filtration structures, which will reduce the sensitivity of the action.

Disinfection

This method is reproduced by exposure to ultraviolet rays, chlorine or ozone. Typically, the method is used to decontaminate water before being discharged into a body of water. The most effective process is considered to be with the use of rays, since it is safe. It is worth considering that their effect can have a detrimental effect on bacteria and various viral microbes.

The type of cleaning based on chlorination implies the disinfection of all microorganisms with chlorine. The main disadvantage of this mechanism is the creation of toxins and carcinogenic compounds. It is for this reason that you should be very careful when using this method.

Ozonation is ozone treatment. Everyone knows that this is a type of gas that contains three oxygen molecules, thereby forming a powerful oxidizing agent that kills microbes. It is important to say that this method is very expensive, therefore it is very rarely used in everyday life. The main sphere of its use is manifested in the production of industrial sectors.

Thermal disposal

Heat treatment of sewage effluents is carried out in situations where other methods do not give results. The principle of operation is to spray liquid into a combustion fuel flare. This is a very effective method, but due to its price and bulk it is found mainly in manufacturing.

Attention! Modern treatment facilities perform the process in several steps, therefore, very often they are programmed to use several methods.

So, the process of purification of sewage water is a prerequisite for the operation of a waste disposal system. It should not be overlooked that these requirements are regulated by sanitary and legal norms.