Efficient nitrogen and phosphorus removal process suitable for low carbon-nitrogen ratio sewage

Abstract

The invention discloses an efficient nitrogen and phosphorus removal process suitable for low carbon-nitrogen ratio sewage. The process comprises the following steps: (1) mixing original sewage or pretreated sewage with return sludge in an anaerobic tank; (2) returning nitrification liquid in a first aerobic tank to a first anoxic tank to mix with the mixed solution subjected to anaerobic treatment; (3) adding the mixed solution after anoxic treatment into the first aerobic tank; (4) adding the mixed solution treated in the first aerobic tank into a second anoxic tank; (5) adding the mixed solution treated in the second anoxic tank into a second aerobic tank; and (6) performing sludge-water separation in a sedimentation tank. The process disclosed by the invention is particularly suitable for treatment of the low carbon-nitrogen ratio sewage, not only can remove organic matters, but also can efficiently remove nitrogen and phosphorus. Moreover, the process can reduce the total tank capacity and the reflux ratio of the nitrification liquid, thereby effectively reducing the construction cost and operating cost; and at present, large-scale engineering application of the process is realized.

Description

technical field [0001] The invention relates to the treatment of sewage with a low carbon-to-nitrogen ratio, in particular to an efficient nitrogen and phosphorus removal process suitable for sewage with a low carbon-to-nitrogen ratio. Background technique [0002] In recent years, explosive environmental incidents caused by eutrophication of water bodies have continuously appeared in my country, and the attention of the whole society to water environment issues has increased significantly. National and local requirements for nitrogen and phosphorus removal in sewage treatment plants are becoming more and more stringent. Nitrogen and phosphorus removal has become one of the important issues that cannot be ignored in the upgrading and transformation of sewage treatment plants. Sewage treatment has moved from the single purpose of removing organic matter to the advanced treatment stage of both removing organic matter and removing nitrogen and phosphorus. [0003] In addition...

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Problems solved by technology

[0003] In addition, the carbon-nitrogen ratio of urban sewage in my country is generally low, coupled with the contradictions in the sludge age of nitrifying bacteria, denitrifying bacteria and phosphorus-accumulating bacteria during operation, and many other factors, resulting in more than 95% of urban sewage treatment plants. The water quality is difficult to meet the first-class A discharge standard of "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB18918-2002)

However, municipal sewage treatment plants generally have a large scale of treatment, and the cost of chemical nitrogen and phosphorus removal is too high, usually only as an auxiliary means, and the effect of biological nitrogen and phosphorus removal directly determines the operating cost

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