Method for removing nitrogen and phosphorus from sewage and special equipment for implementing method

Abstract

The invention relates to a method for removing nitrogen and phosphorus from sewage. According to the method, part of inlet water of a sewage plant directly enters a denitrifying bacterium multiplication tank, after subjected to denitrifying bacterium multiplication, a mixed solution in the denitrifying bacterium multiplication tank is added into an anaerobic tank, and the effect of nitrogen removal by denitrification of the sewage plant can be remarkably improved. Meanwhile, nitrifying bacteria are added into the anaerobic tank, so that the speed of removal by denitrification of NO3-N in returned sludge by activated sludge can be accelerated, a strict anaerobic environment can be formed in the anaerobic tank, anaerobic and aerobic biological phosphorus removal of the activated sludge is facilitated, and the biological phosphorous removal effect of the sewage plant can be improved. The invention also provides special equipment for implementing the method. The special equipment comprises a grit chamber, an anaerobic tank, an anoxic tank, an aerobic tank and a secondary sedimentation tank along a sewage flowing direction, and also comprises a denitrifying bacterium multiplication tank, wherein the denitrifying bacterium multiplication tank is communicated with a water inlet pipe of the sewage plant and the anaerobic tank.

Description

technical field [0001] This application relates to the field of urban domestic sewage treatment. It specifically relates to a method for improving the denitrification and dephosphorization effects of sewage, and special equipment thereof. Background technique [0002] There are more than 3,700 urban sewage plants in my country, with a total treatment capacity of 150 million m 3 / d, the actual processing volume is about 130 million m 3 / d. Pollutants in urban domestic sewage mainly include organic matter (COD Cr 、BOD 5 Indicated), N pollutants (in NH 3 -N, TN means), P pollutants, SS, etc. In the prior art, the secondary activated sludge method is generally used to treat urban domestic sewage, and the main process is A 2 O, oxidation ditch, SBR, organic matter in sewage, NH 3 -N is relatively easy to remove. After secondary treatment, organic matter and NH 3 -N can meet the requirements of Class IV water bodies on the surface; after secondary treatment of P pollutant...

AI Technical Summary

Problems solved by technology

In the prior art, the secondary activated sludge method is generally used to treat urban domestic sewage, and the main process is A 2 O, oxidation ditch, SBR, organic matter in sewage, NH 3 -N is relatively easy to remove. After secondary treatment, organic matter and NH 3 -N can meet the requirements of Class IV water bodies on the surface; after secondary treatment of P pollutants and SS, and then advanced treatment (dosing flocculation + filtration), the effluent TP can meet the requirements of Class IV water bodies on the surface, and the SS content of the effluent is low and the apparent The properties are good; the TN removal rate is related to the reflux rate. Generally, when the reflux rate (including the internal reflux rQ and the external reflux RQ) is (r+R)Q, theoretically, the TN removal rate However, the actual operation results of a large number of sewage plants show that after optimized operation, the effluent TN of the sewage plant is about 11±3mg / L, which can reach Grade A (≤15mg / L), but the denitrification rate cannot reach η = r + R r + R + 1 , Effluent TN is still high

[0003] The effluent from the sewage treatment plant has a high TN and belongs to the super-eutrophic type, which is not conducive to maintaining and improving the urban water environment. Using such reclaimed water to replenish urban rivers and lakes will easily cause water quality deterioration, and eutrophication of the water body occurs from time to time. For this reason, many The city has upgraded the standard and built additional biological denitrification advanced treatment facilities to reduce the TN of the effluent.

The follow-up biological denitrification facilities of the secondary sewage plant not only increase the project investment, but also have lengthy technological process, large area, and complicated management. Necessary to require an external carbon source, leading to high cost of producing recycled water

The real reason for the low nitrogen removal rate of the existing nitrogen and phosphorus removal sewage plants is that the survival and competition ability of denitrifying bacteria in the activated sludge system is weak, and they are in a weak position in the competition with other bacteria, making the activated sludge system The number of denitrifying bacteria is small, which weakens the denitrification ability of activated sludge

Images