The biochemical water treatment method takes advantage of the various bacteria microorganisms that exist in nature to decompose organic matter into harmless substances and purify the waste water.
The biochemical water treatment method can be divided into activated sludge process, biofilm method, biological oxidation tower, land treatment system and anaerobic biological water treatment method.
Process of biochemical water treatment:
Raw water, grille, regulating pool, contact oxidation pond, sedimentation, filtration, disinfection, effluent.
1. Activated sludge water treatment method.
(1) pure oxygen aeration method.
The first pure oxygen aerated sewage treatment plant was built in 1968 in the United States.
Pure oxygen aeration is widely used because of the decreasing cost of producing oxygen.
(2) deep water aeration method.
Increase the depth of the aeration tank can increase the water pressure, so as to increase the solubility of oxygen in water, the dissolution rate of oxygen phase should also increase quickly, as a result, deep water aeration pool of dissolved oxygen is higher than normal aerator, general is to pool depth increased from the original 4 m to 10 m or so.
(3) jet aeration method.
Of sewage and sludge mixture through the jet device, as a result of high speed jet pressure, thus there are a large number of air suction, air fully contact with the mixture, improves the oxygen uptake rate of wastewater, so that the sewage efficiency was improved.
(4) add chemical coagulant and activated carbon method.
The chemical coagulant and activated carbon in the aeration tank of activated sludge method are equivalent to physicochemical treatment at the same time as biochemical treatment.
Activated carbon can be used as the carrier of microorganism and has the effect of assisting solid settlement, and the removal rate of BOD and COD is improved to purify water.
(5) biological contact oxidation.
This is a new type of sewage treatment method with the characteristics of activated sludge and biological filtration method. The contact oxidation pool is used to replace the general aeration tank to contact the sedimentation tank instead of the commonly used sedimentation tank.
(6) pipeline aeration aeration.
This method is to allow the sewage to be aerated in the pressure pipeline and to carry out the long-distance transportation.
Due to the lack of equipment, investment and operating expenses can be reduced.
Aeration: flow aeration, using aeration fan in waste water will be compressed air blowing constantly, guarantee have a certain amount of dissolved oxygen in water, in order to maintain life activities of microorganism, decompose organic matter in water, in order to achieve the purification effect of water treatment.