Sewage treatment system for improved A<2>O process

Abstract

The invention provides a sewage treatment system for an improved A<2>O process, belonging to the technical field of sewage treatment. The sewage treatment system concretely comprises a coarse screen well, a fine screen well, an anaerobic pool, an anoxic pool, an aerobic pool and a secondary sedimentation tank, wherein the anaerobic pool is inoculated with domesticated anaerobic sludge for carryingout an anaerobic ammonium oxidation reaction; the top of the anaerobic tank is provided with an exhaust port; an internal reflux mixed liquid pipeline is arranged between the aerobic pool and the anaerobic pool so as to enable nitrifying liquid to flow back; the reflux ratio of internal reflux is 300-500%; an external reflux sludge pipeline is arranged between the secondary sedimentation tank andthe anaerobic pool, and the reflux ratio of external reflux is 120-200%, and the secondary sedimentation tank is also provided with a residual sewage discharge outlet. The removal of total nitrogen is completed by a combined action of anaerobic ammonium oxidation bacteria and denitrifying bacteria, so that the denitrification ability is high; furthermore, the bacteria do not compete with phosphorus-accumulating bacteria for a carbon source and a growth space, so that the phosphorous removal efficiency is high.

Description

technical field [0001] The invention relates to the technical field of sewage treatment, in particular to an improved A 2 O process sewage treatment system. Background technique [0002] A 2 The O process, also known as the AAO process, is an anaerobic-anoxic-aerobic process. It is a commonly used secondary sewage treatment process, which has the effect of synchronous nitrogen and phosphorus removal. The process is: sewage and return sludge first enter The anaerobic tank (DO<0.2mg / L) is completely mixed, and after a certain period of anaerobic decomposition, part of the BOD is removed and part of the nitrogen-containing compounds are converted into N 2 Release, the phosphorus-accumulating microorganisms in the return sludge release phosphorus to meet the demand of bacteria for phosphorus, and then the sewage flows into the anoxic tank (DO≤0.5mg / L), and the denitrifying bacteria in the tank use the undecomposed carbon in the sewage The organic matter is the carbon sourc...

AI Technical Summary

Problems solved by technology

In anaerobic / anoxic / aerobic (A 2 O) In the process of treating urban sewage, due to the water quality characteristics of urban sewage low in organic matter and high in nitrogen and phosphorus, the carbon source is insufficient, which makes denitrification and denitrification in this process unsatisfactory, and it is difficult to achieve a good simultaneous denitrification and phosphorus removal effect

[0003] Chinese Patent No. CN201310474121.5 discloses an improved A 2 O sewage treatment method, through the biological phase separator set in the aerobic tank, the sludge is preliminarily precipitated and then enters the sedimentation tank, and the supernatant in the biological phase separator is returned to the anoxic tank; although the good is increased to a certain extent However, the sludge returned from the aerobic tank will entrain more nitrate nitrogen, thereby increasing the consumption of organic matter in the anaerobic tank, hindering anaerobic phosphorus release, and then affecting the denitrification reaction and good performance of the anoxic tank. The phosphorus-accumulating bacteria in the aerobic tank absorb phosphorus; secondly, the insufficient denitrification reaction in the anoxic tank will cause the sewage entering the aerobic tank to contain a certain amount of nitrate nitrogen, resulting in a high concentration of ammonia nitrogen in the effluent and a high efficiency of total nitrogen purification. Low

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