If pollutants and toxic wastes enter water bodies from the results of industrial enterprises, it is likely that the abundant flowering of water will develop, leading to poisoning and death of the inhabitants of water bodies. Therefore, it is so important to prevent discharges of untreated water into water bodies, especially in those where there are many commercial fish. Biochemical wastewater treatment is used as the main method of wastewater treatment.
The method of biochemical purification is applicable when wastewater is represented by organic contaminants. It includes the mineralization of pollution, which occurs as a result of the activity of microorganisms using organic substances present in the effluents as their food.
So, in the biochemical purification of waste water, pollution related to organic waste is oxidized by the action of bacteria. With such cleansing, not only organic substances are oxidized, but also the energy required for their vital function is released. Some of the energy is expended to increase the mass of bacteria, the amount of activated sludge and the biological film that appears in the treatment facilities.
Types of biochemical purification
Microorganisms that take part in the process of mineralization of organic pollutants, relative to oxygen are divided into:
aerobic;
Anaerobic
The first kind of bacteria needs oxygen to sustain life and development, and the second kind of microorganism does not need oxygen.
Cleaning aerobic
Such biochemical wastewater treatment is performed using aerobic bacteria (mineralizers), which “feed” on organic substances, while intensively consuming dissolved oxygen in the water. When it is fed, the carrier medium is favorable for the life of the bacteria. Such a medium can be a layer of sand, the thickness of which is 1.5 meters. This method was used for the first time in London (in 1866) – it was called “drip filtration.”
An improved form of drip filtration is the method of a percolation filter, consisting in spraying waste water into the rock. A widespread perpolation filter became in the production of plastics with the necessary characteristics. And today, in systems for the purification of effluents, bacterial material accumulates on discs of plastic, which are on a rotating axis. A drip filtering is used today only in a mild climate and the availability of cheap land.
Necessary conditions for the life of microorganisms
For aerobic treatment plants to be used effectively, the following requirements must be met:
Wastewater must consist of organic contaminants that can be oxidized biochemically;
the structure must be provided with sufficient oxygen;
the water temperature should be from minus 100 to plus 300;
there must be an active reaction of the water to be purified;
There should be no toxic substances in concentrations that are toxic to microorganisms
Cleaning with activated sludge
Cleaning with activated sludge is considered to be the most universal today. This method is used in mixing wastewater and silt, which was formed during the oxidation of water. Addition of activated sludge to the waste liquid leads to the decomposition of substances of an organic nature – as a result, carbon dioxide and water are formed.
Microorganisms that are in active sludge, process such wastes, from which the activated sludge turned out. If there are other substances in the sewage, some more time will pass for the multiplication of bacteria, which will oxidize these elements. During water treatment, the activated sludge is periodically withdrawn from the purification system.
For natural aerobic cleansing, natural conditions and structures created for this purpose by man are used. Under natural conditions, the process of water purification on the fields of irrigation, filtration, biological ponds is assumed. As units of the artificial plan, biofilters and aerotanks act with different design features. As a rule, water treatment in artificial structures is faster than it is carried out under natural conditions.
Cleaning anaerobic
For many methods of water purification, including in the biochemical treatment of wastewater, there are precipitations containing substances of an organic and inorganic nature. With the help of anaerobic microorganisms during fermentation, these substances are destroyed. To neutralize precipitation and sewage, the process of methane fermentation is applied. We apply the anaerobic method and as the first stage of cleaning highly concentrated industrial effluents.
English
