What is the city sewerage system and how it works

City sewerage is set up to collect waste fluids, human waste products, sediment water, and household waste. If the system works without problems, and the drains are cleaned with high quality, even in a metropolis, you can preserve the natural environment and environmental safety.

Types and device of city sewerage

Citywide sewer pipelines are divided into three types:

• Household. It is necessary for the drainage of wastewater from residential buildings and institutions. It is the largest branch of the citywide sewer network.
• Industrial. Allows you to transport liquid industrial wastewater. Such waste is the most hazardous and must be thoroughly cleaned before disposal.
• Stormy. It is used to remove atmospheric precipitation from the streets. The rainwater drainage system is equipped so that water flows are not only absorbed into the ground, but also directed into the water intake.

The device of the urban system differs from the autonomous sewage system in scale and in the presence of fecal pumps. After all, it is almost impossible to overtake a large volume of drains to the treatment devices. The mainline scheme includes waste pipes, collectors, wells and sewage treatment stations.

For the correct arrangement of the sewage pipeline in the city, they are guided by the regulatory documents: GOST 21.704-2011 and SNiP "External networks and structures of water supply and sewerage".

The principle of operation of a city-wide highway

How the sewerage system works in the city:

1. All waste water, except for sedimentary water, is transported through the receiving mains to the floor outlets, then to the vertical riser.
2. The riser in the basement is connected to the outlet, and he is connected to the nearest sewer well. The reservoir is equipped at a seven-meter distance from the house below the level of freezing of the ground.
3. Large debris is retained in the well, fat traps are installed. The well reservoir protects the pipes from blockages.

Depending on the purpose and the total number of connected buildings, several wells are equipped. There, pipes are connected, a step-by-step purification of the liquid is carried out. If one tank fails, it is temporarily replaced by another. After passing through the wells, the wastewater is directed through the collector pipe to the treatment plant.

The work of the sewage system in urban conditions is supervised by the organizations of housing and communal services. If there is an unpleasant smell in the entrance or a pipe burst in the basement, you need to contact the management company or the housing inspectorate.

Basic wastewater treatment methods

The principle of sewerage drainage implies separate branches for domestic sewage and stormwater. The effluent should not be mixed, since the sedimentary water is clean enough to be sent to natural bodies of water after slight filtration.

Other waste liquids require cleaning at specially equipped stations:

• The mechanical cleaning method removes plastic, broken stone, sand and other solid debris from the drains. Part of it has already settled in the sand traps of the sewer network. These devices are also units for mechanical cleaning and are necessary to prevent blockages in the line. The principle of cleaning is based on the force of gravity, due to which heavy debris precipitates on the bottom of filtration plants.
• Chemical and physicochemical cleaning of sewer drains is based on the interaction of chemicals with pollutants, most often of inorganic origin. Harmful substances are oxidized or neutralized, precipitated and removed. The method is suitable for the clarification of industrial effluents, since neither in the storm drain nor in the utility network there is so much active chemical impurities. If the production is classified as harmful, the initial treatment of liquid waste must be carried out on the basis of the enterprise.
• Bio-purification is aimed at eliminating pathogenic microorganisms, nitrogenous and phosphorus compounds. Such contamination is most often found in domestic wastewater. To lighten them, methane tanks, biological filters, activated sludge, ultraviolet irradiation and colonies of purifying bacteria are used.

The mechanical method is used primarily for all types of wastewater. If chemical treatment is required, first purification is carried out by mechanics, then biological purification, and only after that chemicals are added.

The operation of sewerage equipment and the purity indicators of clarified water must comply with all legislative and regulatory criteria. The health, safety and comfort of citizens depends on the correct arrangement of drainage networks.