Sewage treatment plant: how to choose the best option

All city apartments and the vast majority of modern country cottages are equipped with engineering systems to remove dirty water and human waste from the dwelling. And if in the first case, all the wastewater flows to the sewage treatment plant of the city, then for a private house this question remains open and is decided by each owner on his own.

Varieties of cleaning systems

Sewage treatment facilities are divided into four main types:

• large objects used to filter the runoff of large populated areas or areas of the city;
• the installations used for cleaning of the sewerage at the industrial enterprises;
• autonomous systems used in private homes (available for making their own hands);
• sewage for collecting stormwater runoff.

Municipal wastewater treatment plants and wastewater treatment systems in factories and plants are complex and expensive complexes. They allow to remove from the incoming waste all mechanical impurities, as well as chemical elements that are harmful to the environment.

The following waste treatment methods are used:

1. Mechanical. This method prepares sewage for further purification steps.

The whole process is divided into several stages:

• large grates and small sieves remove large fractions from the effluent;
• frequent filters, sand traps emit sand from the liquid, as well as small particles of soil, stone, rubble and so on;
• membrane filter produces final wastewater treatment;
• water enters the tank where the smallest wastes are deposited.

1. Biological. Special bacteria clean sewage from organic pollutants.

There are several varieties of this cleaning method:

• using activated sludge;
• using biological filters;
• using anaerobic fermentation.

1. Physico-chemical. This method is very effective. Chlorination and ozonation are most commonly used.

These procedures are mandatory if water is discharged from a sewage treatment plant into an open water body or soil. The bottom line is that the liquid is treated for some time with chlorine or passes through special ultrasonic filtering systems that kill the bacteria.

Sometimes, sewage treatment facilities are connected into a single external network and water supply and sewage facilities, which allows reducing the costs of their design, construction and operation.

For private houses, individual design of sewage treatment facilities is carried out.

The most common types are:

• cesspools;
• individual septic tanks;
• ready sewage treatment plants.

Tip! When deciding on the development and construction of a sewage treatment plant, the determining factor should not be the price of work, but the efficiency and cost of operation. Having built a small cesspool, you can splurge on the cost of cleaning services.

Types of autonomous treatment facilities

Cesspit

If you have the opportunity to allocate only a small amount of money for the construction of sewage treatment facilities, the arrangement of a cesspool or the purchase and installation of an airtight container for waste collection would be the most appropriate option.

This design has many disadvantages:

• the need for periodic cleaning of the tank or pit, which affects the cost of operating the facility;
• the formation of an unpleasant smell on the land plot (if an airtight container is used, equipped with a properly installed ventilation pipe, this can be avoided);
•  the appearance of many insects for which human waste is a favorable habitat;
• environmental damage - possible contamination of the soil and (or) groundwater (this drawback is not present if a properly installed accumulative containment tank is used).

Note! The cesspool or storage tank is not a sewage treatment plant in the truest sense of the word. Instructions for their use requires regular cleaning of the object with the help of ashenizatorsky equipment.

Individual septic tank

Septic - the most common way of arranging local sewage for country cottages. Designing a sewage treatment plant of this type begins with determining the number of people living in the house and the availability of various household appliances that discharge water into the sewage system.

Based on these parameters, you should choose one of the existing variants of the septic tank, as well as to properly carry out work on its construction.

The simplest scheme is a few tanks communicating with each other using pipes that are located at a strictly defined height:

• the first reservoir serves to separate out heavy insoluble elements, sand and soil from water;
• the second tank is necessary for biological treatment - special microorganisms break up human waste into simple elements that sink to the bottom in the form of sludge;
• the third element is the filtration system.

To ensure that the sanitary condition of a small land plot does not deteriorate as a result of the removal of wastewater from a septic tank, it is better to install a completely hermetic structure.

Here are some tips that will be useful to you in the case of self-built individual septic tank:

1. For manufacturing, you can use ready-made plastic containers or concrete rings of a suitable diameter (it is determined based on the volume of sewage).
2. If ready-made concrete rings are used, all joints should be carefully sealed with special bitumen mastics.
3. The sewage pipe through which wastewater is discharged from a residential building should have a slope of at least 3 cm per meter of length. This will allow the waste to move under the influence of gravity and prevent the formation of blockages.
4. When a plastic container is used, it should be installed in a pit, whose dimensions are 30-40 cm higher than the dimensions of the collector. Then backfill the sand with intermediate tamping.
5. The septic tank should be equipped with a hatch through which pumping of the waste settled to the bottom is performed.
6. Ventilation pipe required. Its top cut should be above the windows of a residential building. Biological gases are lighter than air, because such a structure will protect the inhabitants from unpleasant smell.

Despite all the advantages, the septic tank still does not provide a high level of cleaning. Only special constructions can deal with this, which will be discussed in the next section.

Biological treatment station

Such a sewage treatment plant is capable of removing 98% of the impurities present there from sewage. This is almost pure water, which is served in the central city water supply.

Biological treatment plants have many design features that distinguish them from widespread septic tanks:

1. The basis is an airtight container made of plastic and equipped with fins, which provide the desired level of rigidity. Inside this tank is divided into several sections, communicating with each other with the help of a complex system of pipes and overflow holes.
2. Wastewater treatment occurs with the help of special bacteria, for which habitat in the tank creates a favorable environment. To this end, the desired temperature is maintained there and ventilation is performed with an air compressor.
3. The whole process is divided into several stages. Water circulates from the tank to the tank and is cleaned by passing through various filters.

Given that living organisms live in a sewage tank, the following rules should be observed when operating biological wastewater treatment plants:

• can not be used to clean water used for washing cars, as it contains chemicals that are deadly to bacteria;
• Do not discharge chlorine into the sewage system, as well as waste from the processing of vegetables and mushrooms.

Choosing the optimal system

In order for the future purification system to meet your expectations, some issues should be solved when choosing one or another option.

1. Type of installation used. Do not forget to calculate the cost of its operation.
2. Cleaning method It is better when the treatment plant uses several different methods.
3. Location. Installation of certain types of sewage treatment plants (for example, a cesspool or septic tank) requires compliance with certain sanitary standards.
4. The way to perform work. Depending on the complexity of the installation, you can mount it yourself or only with the help of specialists and engineering equipment.

Stormwater treatment

This system is designed to collect and clean water that falls on the site during rain and during the melting of snow.

Considering that such waste waters contain sand, dirt and oil products in large quantities, a slightly different system should be used to clean them.

Cleaning of storm drains occurs in two stages:

• mechanical - using a filter system;
• physicomechanical - special devices are used that emit residues of oil, gasoline and diesel fuel from water.

Conclusion

Having established and having started up sewer system in operation, do not forget about its correct and timely service. More details about wastewater disposal systems can be found in the video in this article.