Wastewater treatment is an indispensable 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 the effluent to be reused for irrigation of land or simply replenishing the soil. In today's article, we will discuss with you the main ways to filter sewer fluid.

To begin with, let's find out what refers 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. Its important characteristic is the presence of pollution obtained in a certain field of application. It is worth considering that the liquid of atmospheric precipitation is also read here.

Types of pollution

Wastewater treatment involves a process that takes place with the right selection of equipment. It is worth considering that its important component is compliance with a certain type of pollution. It is for this reason that let's find out their species that may be in wastewater:

• Mineral pollution. This type includes all inorganic components, such as: salt, earth, etc.
• organic matter. This is a sewage liquid containing in its composition the remains of the world of flora and fauna. Their composition usually consists of chemical organics and polymers.
• Biological components. They are bacteria and other various microorganisms.

Attention! In most cases, a sewer drain incorporates all three components. If these are household drains, then organics will relate to minerals as 3 to 2. As for bioorganisms, their number depends on the environment.

Norms for cleaning

Any water treatment plant is required to perform a certain level of processing. It should be noted that regulated strict standards are prescribed only for the industrial sector. In addition, the ratio of each type of impurity is fixed by law. For example, iron after treatment should be present in an amount of not more than 0.1 mg per liter.

In relation to domestic plums, the requirements are more lenient. But this is no reason to relax. One of the most important rules for handling wastewater on a private property is that untreated wastewater cannot be released into the environment. For violation of this regulation, the owner of the house will be held administratively liable.

Important! To date, the state regulates only the maximum possible amount of impurities in water. At the moment, this only applies to draining into a reservoir. But remember that the test can also make these claims in relation to the withdrawal of runoff into the soil.

Wastewater Treatment Methods

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

• destructive species;
• recovery methods.

For the former, a characteristic feature is the process of dividing effluents into simple components, which can later be easily removed, for example, in the form of gas. The second types select all valuable substances from the sewage liquid 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 purify wastewater. 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;
• Physical and chemical;
• Method of disinfection;
• Thermal recycling.

Consider in detail the methods of wastewater treatment.

mechanical way

This is one of the simplest options. The process itself includes the removal from the drains of all components that do not dissolve. What are these components? First of all, these include solid particles and fat. Sewer water is passed through a sieve and a sump, which then only passes liquid with small particles.

The best option for mechanical treatment of sewage water is the membrane method. Its main feature is nothing less than the best purification 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 using 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 proven that drains get rid of nitrogen and phosphorus, which are dangerous for 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, aerobic bacteria, then it is possible to install a biofilter or aeration tank. These designs have a high cleaning efficiency and can deal with activated sludge. With anaerobic microorganisms, a fermentation process occurs that converts organic matter into methane and carbon dioxide.

Biofilters and aerotanks with activated sludge are used for such cleaning. They are highly purified and more efficient than biofilters for wastewater treatment. In aerotanks, water is aerated and its deep biological treatment is carried out. In addition, the result is activated sludge, which is a good fertilizer. Anaerobic wastewater treatment is carried out without access to oxygen. Under the influence of anaerobic bacteria, the process of fermentation and the conversion 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.

Physical and chemical 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 breaking down the organic constituents of the water to produce inorganics.
• Coagulation is the purification of water, which is carried out when the 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 precipitation. Educated flakes are engaged in wastewater treatment.

The physico-chemical process has a large number of advantages, for example, the removal of toxins and impurities that are not able to oxidize. It is also worth adding that this method provides a very high percentage of cleaning. This method can easily automate the dimensions of structures for filtering, 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 disinfect water before being discharged into a reservoir. The most effective process is considered to be with the use of rays, as it is safe. It is worth considering that their impact 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. For this reason, you should be very careful when using this method.

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

Thermal disposal

Thermal treatment of sewage effluents is carried out in situations where other methods fail. The principle of operation is to spray the liquid in the combustion fuel torch. This is a very effective method, but due to its price and volume, it is found mainly in production.

Attention! Modern treatment plants perform a process in several steps, so they are often programmed to use several methods.

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

Plumbing is an integral part of modern comfort, and where there is water supply, there must also be drainage. But what to do with the accumulated waste? Now there are many options for solving this problem, ranging from primitive recycling to complete purification of the contaminated fraction from process water. This article discusses the most common methods of wastewater treatment, the principle of their operation, the main pros and cons of such systems.

Wastewater treatment methods

First you need to understand what is wastewater? This category includes any drains that contain any impurities and contaminants. These include:

1. Household sewerage of the residential sector. It contains mainly waste products, biological waste of animal origin, such as fat and food particles. Wastewater treatment technology can be done locally or globally;
2. Industrial effluents contain production waste, chemical elements, polymers or petroleum products. The processing of such contaminants differs from cleaning domestic sewers, this process is more complex and includes a set of activities with several levels. Such installations are able not only to process wastewater, but also to provide the enterprise with water for production needs.

Thus, based on the type of sewage, it is possible to determine the type of treatment plant that will be most appropriate to achieve the desired result and level of treatment.

Wastewater treatment methods can be classified into three types:

1. Mechanical methods of wastewater treatment. As a rule, this stage is considered preparatory, since this is the most primitive method in which there is no other than physical impact on pollution from large fragments. Mechanical wastewater treatment is carried out in several ways:

• Straining. At this stage, the drains are passed through a steel or plastic grate that holds large elements and fibers. Most often, such a mechanism is equipped with an electric drive, it rotates the grid during the water supply, and at the top point all contaminants are removed for disposal;
• Settling. The settling mechanism is based on the physical property of the material to settle on the bottom of the tank. Since water is lighter than the main types of pollution, all elements sink down and accumulate in the water column. After precipitation, contaminants are removed from the sump by emptying it or draining through the bottom of the channel;
• Filtration is carried out using a catching grid with a fine mesh. This method is justified in cases where there are no large contaminants in the effluents or as an intermediate stage of treatment;
• Separation or centrifugation. One of the most modern types of separation of water from dirty drains. The principle of operation of this device is based on the movement of water in a spiral in a special drum, in the process of such rotation, large and suspended particles are separated from industrial water.

This method is one of the main methods of wastewater treatment.

1. Chemical methods of wastewater treatment. This method is designed to separate substances dissolved in wastewater from the main mass by adding special reagents, which, when released into a polluted environment, react with the liquid and contribute to the precipitation of harmful substances. Chemical wastewater treatment, depending on the additives used, is divided into two subsections:

• Neutralization with acids and alkalis. At this stage, chemicals are added to the drains, which bring the liquid to the required value and weight of hydrogen. Most often this method is used in the textile and other industries;
• Oxidation using chemical reagents, which can be liquefied chlorine and its other derivatives. The main direction in the processing of such an installation is the treatment of wastewater with a high content of heavy metals.

1. Physico-chemical methods of wastewater treatment. This is one of the most advanced methods of disposal of contaminated liquid, which includes several stages of separation and removal of finely dispersed and hardly soluble organic and non-organic elements. As well as the previous methods of processing wastewater, this process can be of several types:

• Coagulation is an action based on coarsening by sticking together small particles when reacting with added reagents. The most commonly used salts are ammonium, copper and iron. In domestic conditions, it is rarely used due to the high cost and large dimensions of the equipment;
• Flotation. In this case, a special installation is needed, into which sewage flows, and natural or chemically created flotation agents, such as oil or petroleum by-products, are added. In order for the cleaning process to be continuous, compressed air is supplied to the separated chamber under high pressure, which, passing through the drains, forms a foamy emulsion. Flotation forms oxygen bubbles that capture molecules from the total composition and lift it to the upper layers. The result is an aggregation of elements in a dense foam. This method is used in metal mining to separate useful ore from other minerals. Also, flotation is used in modern urban wastewater treatment plants;
• Sorption cleaning of household drains. The most advanced cleaning method, it uses large sorbents of natural or chemical origin. Contaminated effluents are mixed with porous material, and after settling into a sediment, the filter is removed from the tank, and the technical fluid can be reused. The level of purification with this method reaches a degree of 95%. The main disadvantage of sorption is the high cost of components and equipment;
• Simple and reverse osmosis. In such a device, domestic wastewater treatment occurs as a result of squeezing water through contaminated drains and a membrane, or the reverse process with the passage of dirty water through a filter element and the separation of waste molecules. The principle of operation in both directions is the same, it is based on the mechanical retention of particles that are larger than water molecules in a special grid. After the filter is filled, it must be removed and changed or cleaned.

All physical and chemical methods of wastewater treatment are mainly used on an industrial scale for large enterprises and factories. The production and household methods differ in the equipment used and the number of processes. But some units are also used in the private sector, for example, flotation or osmus.

1. Biological method of sewage treatment. Most often, this method is used in the construction of treatment facilities for an individual dwelling with an autonomous communication system. Its principle of operation is based on the processing of contaminants by creating a nutrient medium for special bacteria intended for wastewater treatment. There are two types of microorganisms suitable for wastewater treatment:

• Anaerobic bacteria - live in a polluted airless sewer environment and feed on biological waste. Anaerobic wastewater treatment has a methane gas by-product, so the tank must be equipped with a gas vent. Another colony of bacteria is called useful sludge, as they live on sand particles contained in the aquatic environment;
• Aerobic bacteria, unlike the previous ones, need a constant supply of air, since they need oxygen for normal life. The waste tank must be equipped with a compressor unit and a supply of pipes for effluent enrichment.

Often, both options are used sequentially to achieve the desired result, then the level of sewage treatment can reach 98%. Such water cannot be used for food, but it is suitable for domestic needs, for example, for watering plants or cleaning. Often the aerobic scheme is used in conjunction with another oxygen method called flotation.

Note! Regardless of the chosen method of domestic wastewater treatment, its design and installation should be carried out by qualified workers, since it will be possible to independently calculate the required power only with a detailed study of all communication parameters.

Stages of wastewater treatment, stages and installation of an autonomous septic tank

Treatment of domestic wastewater in the enterprise and in the private sector are very different from each other. In individual housing, a combined treatment system is often used, which includes several stages of liquid treatment to the state of process water. The construction of such a structure begins with the calculation of power and location. As a rule, the septic tank is located at some distance from the residential building closer to the exit from the site. This is done so that during operation there are no problems with the removal of waste material and waste.

The next step will be digging a pit for the tanks. Many manufacturers make rigid plastic tanks with built-in baffles and compartments for overflow, filtration and recycling. Such a product is much more expensive than reinforced concrete rings, since its production is expensive, but has the advantage of ease of installation and maintenance, as well as space saving. Warranty for plastic containers for more than fifty years.

It is important to observe the dimensions of the pit so that it is 20-30 cm larger around the perimeter, this will facilitate installation and prevent the destruction of the walls of the pit.

Geotextiles are laid on the sand and gravel cushion, which will prevent the container from sagging under the influence of heavy weight. After ramming the base, the septic tank itself is mounted, it can be factory-made or made independently from reinforced concrete rings. If a plastic tank is used, then weighting must be placed on the bottom so that when precipitation occurs, the container does not float out.

The sewer pipe is connected along the top cover in such a way that there is an air gap between the accumulated drains and the incoming liquid. To prevent the entry of an unpleasant odor from the septic tank into the room, it is recommended to install a check valve that works only in one direction, regulating the flows.

Most often, the first stage of sewage water treatment is natural filtration from large fragments of non-biological origin. For this purpose, an overflow threshold with a sand trap is provided in the tank, which screens out elements unsuitable for processing from the bulk.

Anaerobic bacteria are located in the next compartment, which purify the liquid from large inclusions that are contained in the thickness of the drains. After processing the main pollution and turning them into carbon dioxide and methane, the bacteria partially die; in order to maintain the required number, it is necessary to periodically renew their population.

After overflow, the recycled water enters the aeration fields. Bacteria live here, feeding on biological waste when enriched with oxygen. Therefore, to ensure the process, it is necessary to continuously supply oxygen to the chamber; without it, all microorganisms will die.

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Sewerage and wastewater treatment in a private country house

Country houses located in country 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 advancing by leaps and bounds, and today many types of domestic wastewater treatment plants have been developed. Recall 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) for deep biological treatment, wastewater treatment plants (STPs), local treatment facilities (VOCs), etc.

In order not to get confused in these names, which essentially 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 in the past or not yet?

Since a consumer who is inexperienced in the problems of private sewerage sometimes misinterprets the meaning of this term, it would not be out of place 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 to the 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, wastewater does not just accumulate, it is their primary decomposition into heavy ones, gradually settling down, and light ones, floating to the surface. Thanks to this treatment method, which is called mechanical, the wastewater is cleaned by 60%, which is a very low degree of purification, and therefore it is forbidden to dump it on the terrain.

Ten-year-old technologies implied the installation of filtration fields in the area adjacent to the house - drain systems, through which soil post-treatment of wastewater from the septic tank took place. Today, this is an outdated method. However, the septic tank itself cannot be discounted. Sometimes it helps to solve certain problems. For example, if we are not talking about a year-round country house, but about a summer house where the family visits seasonally or periodically. Since the septic tank is suitable for processing a relatively small volume (1 -3 m 3 / s.) of domestic wastewater and fecal matter, it will be necessary to call in a sewage truck from time to time. To reduce the rate of filling the tank, drains can be divided into "gray" (water after washing dishes, bathing, washing) and "black" (receipts from the toilet) and send only "black" to the septic tank.

In any case, for a house of periodic stay, a septic tank will be the most economical solution. Sometimes it has to be set for other reasons. For example, in water protection zones, where it is forbidden to use even VOCs that clean wastewater 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 purified water by gravity into the existing drainage network
b) Discharge of wastewater to an intermediate well in which a drainage pump is installed
c) Pressure discharge of wastewater into a road ditch
d) Gravity discharge of sewage into a filtering (drainage) well

Principles of operation of aeration VOCs

There are a great many individual sewer installations on the Russian market. Some of them, called differently, are actually almost "twins". And 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 constructive difference between 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 the oxygen contained in the air for their life activity. How does it enter the VOC tank? Aeration (saturation of water with air oxygen) is forced: 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 commonly, 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 camera compartments for different models may be different.

Their common purpose is to sequentially purify domestic wastewater to the parameters specified in the technical data sheet. This is done in the following way. Wastewater is sent to a septic tank, where it is fermented, suspended solids are separated, sand and other insoluble impurities are settled. After that, partially clarified effluents enter the anaerobic bioreactor, where they are treated with anaerobic sludge (community of microorganisms). The process takes place without access to oxygen. Anaerobic bacteria convert organic compounds that are difficult to oxidize into easily oxidizable ones. Then comes the turn of cleaning in the aerotank of the 1st stage with the effect of oxygen (using forced aeration). Here, wastewater is mixed with activated sludge, which absorbs and oxidizes pollution. After that, the wastewater enters the second stage aerotank, where it is further purified (by oxidation and adsorption) with a biofilm of microorganisms formed on a load of artificial "algae" with continuous fine-bubble aeration. Further, in the secondary clarifier, the activated sludge is deposited and returned to the septic tank using an airlift, and the wastewater, purified up to 98%, is discharged to a lower relief place. 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. Integrated VOCs consist of a vertical sedimentation tank with baffles (septic tank) and a bioreactor located above it. Sediment settling and anaerobic treatment take place in the septic tank. In the bioreactor - aerobic (with oxygen) treatment of already clarified wastewater. Bacteria attach to the biofeed 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 wastewater and accelerates the process of precipitation. 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 drains.

What does the consumer need to know?

Aeration VOCs do not allow volley discharge of wastewater (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 dramatically, due to which the colony of bacteria that is used for cleaning is partially (or completely) washed out. And consequently, for some time after a volley discharge, the installation will not be able to treat wastewater to the indicators indicated in the passport. A prolonged power outage also negatively affects the operation of systems of the first type, namely, it leads to the partial or complete death of a bacterial colony. True, some manufacturers "forget" to notify the buyer about this. Others convince that this is not a significant drawback of the devices, because you just need to put the bacteria bought in the store for septic tanks into the container, and the installation will begin to function as before. This is true, but reaching the degree of wastewater treatment declared by the manufacturer will occur in this case no earlier than in two to three weeks.

But for complex VOCs, neither a salvo dump nor a power outage threatens negative consequences. The reason for this is in the design 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, there is a constant mixing of activated sludge. In complex VOCs, sludge is deposited in a separate chamber, where it is in a state of relative rest, and since bacteria in such systems live not only in water, but also in a bioreactor, they are not threatened by leaching with abnormal effluents, as well as death due to shutdown electricity. Even with a long interruption in the power supply, the bacteria on the biofilter are alive for three months. The output 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 installations, as this can lead to blockage of the pumps that ensure the operation of the station. In addition, it is not desirable to drain chemical household detergents there, which 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 debris (toilet paper, napkins, food debris, pet hair, polymer films) that has fallen into them 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, together 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 in continuous mode. However, complex VOCs have somewhat lower electricity consumption due to the fact that they do not use a compressor, but a timed pump (15 min./on - 15 min./off).

On the Russian market there are systems of varying complexity from both domestic and foreign manufacturers. 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 an economical mode, with volley discharges - to a forced one. 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 treated in the installation goes. The easiest option is to divert it by gravity. After treatment in VOCs, effluents are discharged directly onto the terrain or into a drainage network (trench, roadside ditch) at least 80-90 cm deep, protected from flooding. The second option is a filter well, used in cases where gravity drainage is not possible.

From the VOC at a distance determined by the project, a reinforced concrete well is made with a depth of about 3 m. Crushed stone is poured onto the bottom of which (in order to increase the performance of the system). The capacity 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 filter cylinder of the well, in sandy loam - 40 l / day. In clay soils or at high groundwater levels, this scheme does not work. In these cases, drainage pumps are used. For pumping purified water from VOCs, submersible devices with a conditional passage (maximum size of impurities) of 10-12 mm are used. The pump can be installed directly in the last chamber of the VOC or in an additional intermediate well, it must be sealed. This is necessary so that the pump does not also pump groundwater.

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

Prices

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

When choosing devices for wastewater 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 per year sometimes reaches 20% of the equipment price.

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 truck. The cost of sewer services is 750-800 rubles / m 3.

What volume of wastewater installation to choose

The choice of a household treatment plant for specific building conditions is a complex multi-factorial task. First of all, it is necessary to calculate the performance of the equipment, since the size of the tank depends on this.

The specific rate of water disposal (according to SNiP 2.04.01-85) is 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 to four people spends an average of 200 liters of water per day on washing, washing dishes and washing, another 200 liters on the toilet, and 400 liters on a shower and bath.

In total, 800 liters are obtained. The size of the container is chosen taking into account that its working volume exceeds the daily rate of water consumption by three to five times. Therefore, in our example, a 4 m 3 tank is needed.

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

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

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

Previously, it was more difficult to organize “life support” according to urban standards in rural areas than in space. Fortunately, times have changed, the issue is also being resolved where the connection to the centralized water supply and sewerage 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 sewerage system.

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

All options for local treatment systems (VOCs) have both “pros” and cons. Let's figure it out!

Local principles

Let's start with some science. It must be understood that any modern device that solves the “toilet” problem (by the way, including the 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 effluents. The solid waste fraction decomposes, other organic compounds are formed, and the water settles. 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 the bacteria involved in these processes are different. When aerobic are taken into account, the degree of purification complies with current hygiene standards; when anaerobic are working - it does not correspond, and additional cleaning is required.

What is a septic tank

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

how many containers connected to each other with nozzles and overflows. Heavy particles sink to the bottom, the most liquid fraction sequentially flows from chamber to chamber. Defending in this way, the plums are gradually cleaned.

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’s not worth unnecessarily complicating the septic tank, three containers are the optimum.

part of a larger whole

A septic tank is not a self-sufficient device. Thanks to anaerobic processes, plums will leave about 65% of pollution in it. Where to put the foul-smelling moisture, which is still far from ideal? It is poured 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 to purify 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 the sediment accumulating at the bottom of the chambers? It is periodically raked out. Alas, one cannot do without a vacuum cleaner. This means that it is necessary to ensure the free access of 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 breaks 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.

Installation requires a significant amount of space on the site.

Access roads are required for maintenance.

Difficult installation of volumetric and heavy equipment.

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

What is a bioseptic

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

Its design provides for a biofilter - a small reservoir with a chemically inert, decay-resistant backfill. It can be, for example, foam balls, shungizite, expanded clay or shell rock. 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 a bioseptic tank is somewhat higher than in a conventional one, and less sediment is formed at the bottom of the chambers. That is, ceteris paribus, the sewer will have to be called less often.

What is an aerotank

In fact, initially the aerotank was called a reservoir in which the treated effluents are mixed with activated sludge - a biocenosis of microorganisms that can absorb organic matter. Today, the installation of deep biological treatment, including this tank, is often called an aerotank. What kind of bioseptic? You could probably say that. But, definitely, the difference between an aeration tank and a septic tank with a biofilter is fundamental: other bacteria, aerobic, are used here.

The operation of the system is based on biological oxidation with the access of air, which is pumped by the compressor. Due to aeration, the oxidation process occurs evenly throughout the volume. The "final product" - odorless sludge - is fed into a special compartment. Filtered water does not need additional purification!

ON A NOTE

Any LOS is designed for a certain number of users. To calculate the volume of the treatment plant, it is recommended to start from 200 l/day per person. The volume of simultaneous discharge of effluents (“volley discharge”) is also important. This indicator can greatly affect the quality of cleaning. The greater the throughput of the VOC per day, the more it should have a margin for the simultaneous reception of discharges from various plumbing units within an hour.

"Pros" and "cons" of the aeration tank

A high degree of wastewater treatment - the product is odorless 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!).

Space is saved on the site - the "filtering field" is not needed.

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

The sewerage device in the absence of a centralized system is a complex engineering task. The sewerage scheme is determined by the type of toilet equipment, the total volume of "gray" wastewater from washbasins, bathtubs, washing machines, and pools. As well as the geological features of the area: the depth of groundwater, the filtering capacity of soils, the presence of water intakes in the immediate vicinity of the treatment facilities.

Wastewater entering the sewer network may contain waste of mineral origin (sand, clay, slag particles, salts, acids, alkalis dissolved in water); rotting organic matter (of animal and vegetable origin); pathogenic bacteria, harmful chemicals. Wastewater treatment methods used in local sewage systems can be divided into three main types: mechanical, chemical and biological.

Chemical cleaning method wastewater is based on the use of various reagents that convert dissolved impurities into a sparingly soluble state. Further, the precipitation of these substances occurs. This method is mainly used for industrial wastewater treatment.

mechanical cleaning It consists in removing from the waste liquid waste of mineral origin, which are in it in an undissolved, and partially in suspension state, as well as from foreign objects floating in wastewater. When using a mechanical cleaning method, sedimentation and filtration of wastewater occurs. One of the disadvantages of this method is that there is no water purification from dissolved organic contaminants. Therefore, mechanical treatment facilities (settlers, sand traps, grates and sieves) are most often a preliminary step before biological treatment.

AT biological treatment Wastewater involves bacteria, which, depending on their relationship to oxygen, are divided into two groups: aerobes (using oxygen dissolved in water during their breathing) and anaerobes (developing in the absence of free oxygen).

Anaerobic (without air access) treatment is carried out in closed containers (methane tanks, septic tanks, two-tier settling tanks), where organic pollutants are fermented with the help of methane-forming anaerobic bacteria.

At aerobic (with air supply) cleaning wastewater use drainage fields, filtering wells, biological filters and aerotanks, in which the cleaning process takes place intensively. Oxygen, necessary for the life of microorganisms, comes from the surrounding air or it is injected with special compressors (blowers). A large amount of organic substances contained in wastewater serves as a favorable nutrient medium for aerobic bacteria, which are able to absorb various organic substances in the course of their life. During biological treatment, activated sludge is created. Sewage is mixed with activated sludge, significantly accelerating and improving the oxidation process. As a result, pathogenic microbes are absorbed by activated sludge, die or become its active agents, or they decay into harmless ones. Due to this, the water loses its tendency to rot, becomes transparent, and its bacterial contamination is reduced.

In modern biological treatment plants, both types of bacteria are used: anaerobes and aerobes. First, the sewage flow enters the tank with anaerobes and oxidizes there for 2-3 days, then it goes through the process of post-treatment in tanks with aerobes or in natural conditions. Waste liquid during biological treatment is almost completely freed from organic matter and harmful bacteria.

Rice. 24. Dry closet

For a summer house, you can choose a cheaper option: arrange for gray water to drain from sinks and showers and use a dry closet (Fig. 24). This is an intermediate option for those who do not want to install an expensive sewage system and at the same time want the “latrine” to be more convenient than the “outhouse” - a backlash or powder closet.

Wastewater treatment is the removal of foreign impurities from them before being discharged into a reservoir or soil. Wastewater can be divided into several categories:

1. household - sewerage;
2. industrial - the result of the work of factories and plants;
3. atmospheric - melt and rain water.

Not only effluents discharged by enterprises should be cleaned, but also domestic ones - from sewer systems. Poorly treated water, even from a small private house, can cause serious damage to the environment.

Previously, sewage was collected in ordinary, so-called cesspools, but due to non-compliance with sanitary standards, they have to be abandoned. Today, autonomous sewage treatment plants are used to collect and treat domestic wastewater, where they are cleaned by 90 - 99%. After that, they can be dumped into open water bodies or the ground.

Cleaning methods

Domestic wastewater may contain soluble or insoluble impurities. Depending on the size of the contained particles, they can be divided into:

• emulsions and suspensions - 0.1 microns;
• colloids - from 0.1 microns to 1 nm;
• dissolved particles.

Cleaning is carried out using various methods and means. Cleaning methods are divided into several groups:

1. mechanical - filtration and hydrodynamic processes;
2. physical and chemical - chemical and heat treatment;
3. biological - processing by bacteria.

When choosing a cleaning method and process, it is necessary to take into account the degree of contamination, the content and size of impurities. Most often, for household (household) effluents, biological and mechanical methods are used.

Video: Methods and facilities for wastewater treatment

Biological wastewater treatment

In nature, water is purified by microorganisms that live in it or the soil. Bacteria decompose organic particles into water gas. This method, although effective, is quite time consuming.

Bacteria need an ideal environment for their life. For example, for aerobic microorganisms, which need oxygen for life, it is necessary to equip aeration systems.

But their brothers - anaerobic bacteria, do not need oxygen and do an excellent job with their duties in sealed containers. But as a result of their work, gas is released, therefore, for buildings in which these microorganisms are used, it is necessary to arrange a ventilation system.

On a note! Biological wastewater treatment is used only after mechanical.

Mechanical Methods

Any wastewater treatment begins with sedimentation or filtration, due to which large impurities are removed from the liquid. For this, coarse filters are used, such as: sieves, grates, sand traps, etc. In most treatment plants, the settling method is used, in which heavier particles settle to the bottom, and light ones move on to the next stage.

On a note! During mechanical treatment, up to 65 - 70% of impurities are removed from domestic wastewater.

Chemical cleaning

This method is based on the addition of chemicals to the drains. As a result of the reaction occurring during the interaction of chemicals with impurities contained in wastewater, a precipitate is formed, which in turn is removed mechanically.

This method allows you to remove up to 25% of soluble and 95% of insoluble impurities. Potassium permanganate, chlorine and other substances capable of disinfecting are used to disinfect water.

Physico-chemical method

For the purification and disinfection of domestic sewage, the physicochemical method is rarely used. It is mainly used in wastewater treatment plants intended for the treatment of industrial wastewater.

Physical and chemical methods include:

• coagulation;
• flocculation;
• flotation;
• adsorption;
• ion exchange method;
• reverse osmosis method.

Since this technique is practically not used in, we will not analyze each item in detail in this article.

Methods used in domestic sewage

The simplest cleaning devices for household sewer systems, which include cesspools, use two main methods in their work: mechanical and biological cleaning. Effluent in these devices is settled and treated by microorganisms.

Most conventional septic tanks use anaerobic bacteria in their work, that is, those that do not need air access. At the same time, cleaning is slow, and the liquid is not completely cleaned, so it is necessary to arrange after-treatment at the outlet - filtration fields.

More advanced treatment plants, in addition to settling and anaerobic biotreatment, use inlet filtration and aerobic microorganisms. As a result, the output is 97-98% purified water.

Cleaning rates

There are no strict requirements for household wastewater. The regulations, in which the permissible concentrations in treated water of a particular substance are recorded, apply only to industrial treatment facilities. However, this does not mean that the crude liquid from can be drained into water bodies or directly onto the ground. For this, they can be held administratively liable.

For household wastewater, the law regulates the concentration of certain substances if they are discharged into open water bodies. The same applies to water that drains into the soil, since over time it will still fall into the reservoir.

On a note! For effective operation of the sewer, follow the rules for its operation. Do not dump garbage into it, as well as pour solvents, paints and varnishes, gasoline and other chemically hazardous substances. Only domestic sewage should enter the sewer system.

Conclusion

There are many methods for wastewater treatment, the choice depends on the nature of the pollution and the requirements for the quality of treated water. Domestic wastewater is treated mainly mechanically and biologically. And the physico-chemical and chemical method is used in large enterprises.

Video: Modern wastewater treatment technologies