Sewage treatment system

Abstract

The invention relates to a sewage treatment system comprising: a pre-anoxic tank which is connected to a sewage inlet pipeline and is used for an anoxic denitrification reaction of returned sludge and the sewage; an anaerobic tank which is connected to the sewage inlet pipeline and communicated with the pre-anoxic tank and is used for anaerobic phosphorus releasing during biochemical dephosphorization; an anoxic tank which is connected to the sewage inlet pipeline and communicated with the anaerobic tank and is used for nitrogen removal by denitrification; an aerobic tank which is communicated with the anoxic tank and is used for degrading organic substances, nitrating organic nitrogen and ammonic nitrogen and absorbing phosphorus; a post-anoxia tank which is communicated with the aerobic tank and is used for performing nitration and denitrification at the same time; and a sequencing batch sloping plate sedimentation tank which is communicated with the post-anoxia tank and is used for separating muddy water and concentrating the returned sludge, herein the returned sludge is flown back to the pre-anoxic tank. The sewage treatment system is excellent in comprehensiveness and flexibility and can flexibly fit various water quality and treatment requirements generally.

Description

technical field [0001] The invention relates to a sewage treatment system, in particular to an urban sewage treatment system. Background technique [0002] Generally speaking, sewage treatment technology can be divided into physical treatment technology, physical chemical treatment technology, biochemical treatment technology and chemical treatment technology, among which biochemical treatment technology of sewage is the most commonly used. There are also many kinds of biochemical treatment technologies, which are mainly classified according to the different conditions of microbial growth conditions and oxygen supply methods. In order to achieve the purpose of nitrogen and phosphorus removal in biological treatment, it is necessary to create anaerobic, anoxic, and aerobic regions in the space or time of the reactor, so as to realize different forms of anaerobic-aerobic phosphorus removal and aerobic-anoxic dephosphorization. Nitrogen, the required hydraulic retention time i...

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Problems solved by technology

[0004] With the increasing eutrophication of water bodies, the nitrogen and phosphorus discharge standards of urban sewage treatment plants are getting higher and higher. At present, the most widely used nitrogen and phosphorus removal process is A / A / O and its improved process. This process is mainly composed of Composed of anaerobic tank, anoxic tank, aerobic tank and secondary sedimentation tank, the removal effect of organic pollutants and suspended solids is good, but there are some disadvantages: ①The removal effect of nitrogen and phosphorus is unstable; ②Influent water quality and quantity The change of the hydraulic pressure has a great influence on the operation effect; ③The design hydraulic retention time is longer, and the operating cost is higher

[0006] SBR and its variant process realize anaerobic, anoxic and aerobic in time series to achieve the function of denitrification and phosphorus removal. The reaction and sedimentation process are concentrated in one pool, which has the advantages of less processing structures, small footprint and flexible operation. and other characteristics, but it also has some disadvantages: ①SBR and its variants both use decanters. Due to the limitation of the water output of the decanters, it is impossible to treat a large amount of water in a single tank, so this process is not suitable for large-scale sewage treatment plants; ②The volume utilization rate of the reactor is low, and the water head loss is large; ③The utilization rate of the system equipment is low, and the control is complicated; ④Affected by the reaction time, the reaction conditions of anaerobic, anoxic and aerobic cannot be fully guaranteed; ⑤The effluent is not continuous, and subsequent treatment difficulty

[0008] The UNITANK process is actually very similar to the three-ditch oxidation ditch process. Although the secondary settling tank and the sludge return system can be omitted, they have ① no obvious independent anaerobic and anoxic areas, which affect the nitrogen and phosphorus removal effect; ② The sludge concentration in the reaction tank is unbalanced. In the later stage of the reaction cycle, the sludge concentration on the inlet side is low, and the sludge concentration on the sedimentation side is high. ③The number of UNITANK process equipment is large, the utilization rate of the equipment is low, and the control is complicated; ④The outlet weir is fixed, and the initial outlet The amount of water is difficult to determine and requires backflow treatment

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