Anaerobic multi-stage aerobic-anoxic dephosphorization and denitrification process

Abstract

The invention relates to multistage anaerobic, aerobic and anoxic dephosphorization and denitrogenation technology, which is mostly suitable for treating urban domestic sewage. The sewage is divided into two parts, namely approximately 30 percent of the sewage is mixed with return sludge and enters into an anaerobic tank, and most of the sewage exceeds the anaerobic tank and directly enters into an anoxic tank for denitrogenation in a multipoint mode; after denitrogenation is completed, the mixed solution is mixed with a small part of the sewage and enters into a secondary settling tank for sludge-water separation; and denitrogenation reaction is continuously completed during sludge-water separation; and the return sludge and nitrite nitrogen and nitrate nitrogen of discharged water are reduced, and residual sludge is discharged regularly. The multistage anaerobic, aerobic and anoxic dephosphorization and denitrogenation technology has high phosphor and nitrogen removal rate, reduces the capacity of a structure, saves investment, fully utilizes carbon sources and simultaneously reduces direct oxygen consumption because the sewage does not directly enter into an aerobic tank and then the carbon sources in the sewage do not directly contact oxygen, and improves the catch rate of air bubbles and obviously saves the aeration cost due to ultrahigh sludge concentration in the aerobic tank under the condition of blast aeration.

Description

Technical field [0001] The invention relates to an anaerobic multi-stage aerobic and anoxic phosphorus and nitrogen removal process, which is especially suitable for urban domestic sewage treatment. Background technique [0002] In recent years, biological dephosphorization and denitrification of sewage has become a research hotspot. Biological phosphorus and nitrogen removal are achieved by phosphorus accumulating bacteria that have excessive accumulation of phosphorus for growth. Phosphorus accumulating bacteria alternately compete with other bacteria for substrate under anaerobic and aerobic conditions, absorb volatile fatty acids under anaerobic conditions, and transport them to the cell, assimilating into intracellular carbon storage (PHB), and at the same time Release the poly-P phosphorous in the cell protoplasm to provide energy; under aerobic conditions, the phosphorous accumulating bacteria store the amount of phosphorous exceeding the growth requirement in the form of ...

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Problems solved by technology

[0003] At present, the wastewater treatment plant adopts a wide range of denitrification and phosphorus removal processes: A 2 / O, SBR, oxidation ditch, etc. These processes are all developed based on the traditional mechanism of nitrification and denitrification, nitrogen and phosphorus removal, but because the nitrifying bacteria in these processes grow slowly, and the nitrification of the traditional activated sludge method The sludge concentration in the process is low, generally only 3-5g / L, so it takes a long time for nitrification. For general domestic sewage, it usually takes more than 5 hours for nitrification, which increases investment and operation. cost

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