What you need to know about domestic wastewater treatment technologies
Waste water must be cleaned of contaminants that can harm the environment and humans after their disposal. There are several technologies that allow to remove harmful impurities and pollution from wastewater, to one degree or another.
Purification of household and industrial wastewater is much more difficult to implement than water purification from a well due to the high concentration of contaminants in wastewater and their heterogeneity.
All this increases the price of autonomous sewerage of a private house, because the wastewater must be cleaned before draining it to the ground, into a ditch or a reservoir, and an effective treatment plant is not cheap.
Pollution in wastewater can be in the thousands, so most often a combination of several cleaning methods is used to remove them. Let's consider each of them separately.
Wastewater treatment methods
Conventionally, all methods of wastewater treatment can be divided into four types:
- mechanical way;
- physical way;
- chemical way;
- biological way.
As a rule, wastewater is treated gradually by all means. First, solid impurities that can damage the treatment equipment are removed mechanically, and then the effluent is treated by a physical, chemical or biological method.
Industrial waste
Practically any technological production, in which water is involved, forms effluents. Moreover, they can contain almost the entire table of chemical elements, so it is much, much more difficult to purify industrial effluents than domestic ones.
Mechanical and physical cleaning
The mechanical and physical cleaning methods include both simple methods - settling, filtration, and complex ones - separation, thermal utilization, flotation, distillation, etc.
For separation, centrifuges are used, in which, under the influence of centrifugal force, solid particles of wastewater are separated from them.
Thermal disposal is accompanied by the incineration of wastewater at a temperature of hundreds of degrees.
Such technically complex methods of cleaning industrial effluents from mechanical particles and contaminants require appropriate equipment, which takes up a lot of space and requires a large amount of electricity. It makes sense to install them if large volumes of wastewater are constantly generated at the production site, however, mechanical treatment of solid fractions is available in almost every enterprise.
Chemical cleaning
The chemical cleaning method allows you to remove contaminants using reagents, most often chlorine, alkali and acid. A big drawback of this method is the need to remove the reagents themselves from purified water.
This method of wastewater treatment also requires complex equipment and financial costs and is used in industry in the case of a large volume of wastewater with impurities that can be removed with reagents.
Biological treatment
Industrial wastewater, as a rule, is not cleaned by biological methods, because the pollution in them is detrimental to any bacteria. But, nevertheless, it is possible to meet the purification of industrial wastewater by aerobic and anaerobic microorganisms at enterprises in the course of which organic waste is generated that requires processing (food industry, animal husbandry, etc.).
Wastewater treatment of urban high-rise buildings
The treatment of household sewage of the city most of all resembles the treatment of wastewater in autonomous sewers. Municipal wastewater treatment plants are different. These can be concrete tanks, filtration fields, ponds, in which there are bacteria that decompose the waste entering them. Natural treatment facilities do not function in winter, because with a decrease in ambient temperature, bacteria stop their vital activity.
That is why, most often in cities, artificially created treatment facilities are used, which maintain comfortable conditions for the life of bacteria throughout the year, regardless of the season.
Cleaning of domestic wastewater in a suburban area
The sewer system of a private house, cottage or dacha practically repeats the sewer system of the city. Here, as well as in the city, effluents are collected through pipes into a treatment plant, in which effluents are processed mainly in a biological way.
An autonomous treatment plant can operate according to one of two technologies - aerobic or anaerobic wastewater treatment. In the first case, oxygen is supplied to the treatment plant, in the second case, oxygen does not participate in the processing process in any way. The aerobic method allows you to treat wastewater up to 98%, the anaerobic method - up to 70%.
Household effluents from private houses contain a large amount of organic pollution. Bacteria in wastewater treatment plants operating according to one technology or another feed on organic contaminants, turning them into simple compounds, carbon dioxide, water. Choosing a treatment plant is half the battle for the construction of a sewerage system on the site, which other facilities will or will not be included in the system, how the pipeline will need to be installed, etc. will depend on this.
But it is not enough to properly make a sewer in a country house or in a country house, it still needs to be properly operated.
Substances that can affect the vital activity of bacteria in the treatment plant should not enter the sewer system of a cottage or a country house. Therefore, each such structure is accompanied by a list of items and substances that should not enter the system:
- chlorine-containing household liquids;
- acids, alkalis;
- gasoline, solvents;
- medicines;
- fertilizers;
- water after regeneration of water treatment system filters;
- building materials (cement, lime);
- film and others.
At the last stage of wastewater treatment in a treatment plant, the method of water disinfection with ultraviolet light can be used. After such cleaning, wastewater can be drained directly on the site or into a reservoir - it will be absolutely safe for the environment.
The principle of operation of treatment facilities
In septic tanks using an anaerobic treatment method, wastewater undergoes a process of decay without oxygen. In such facilities, only 70% of wastewater is processed, because without oxygen it is impossible to destroy organic matter. All that part of the waste that has not been recycled settles to the bottom of the septic tank, accumulating there. This sediment contains a large number of dangerous microorganisms, so it must be pumped out at least once a year with a sewage machine.
Devices using the anaerobic method - septic tank TANK, KEDR and others. The water received after the septic tank requires post-treatment in soil filtration facilities.
Facilities that use the aerobic processing method are also called deep biological treatment plants. The bacteria used in these stations, with the help of oxygen, are able to effectively decompose household pollution. The sediment that forms in this case in a small amount can be used as fertilizer, and the liquid obtained at the outlet of the station can be used to water plants or drain into a ditch, river or lake - it no longer contains harmful and hazardous substances.
