Primary sludge fermentation pretreatment method and system for improving performances of dephosphorization and denitrification on town sewage

Abstract

The invention relates to primary sludge fermentation pretreatment method and system for improving the performances of dephosphorization and denitrification on town sewage. In an integrated flocculation fermentation settling pond, a suspended sludge floc layer is formed and maintained with a certain interface height through auxiliary stirring and natural flocculent settling so as to realize the flocculent settling of suspended solids and colloids and tendentious separation of suspended solid inorganic components, and biotic populations in the suspended sludge floc layer have stronger effects of hydrolysis and fermentation on the suspended solids, the colloids and soluble organic matters. In the invention, the resolution ratio on the suspended solids and the colloids is 15-50 percent, the volatile fatty acid concentration is improved by 20-150 percent, the VSS / SS (Volatile Suspended Solid / Suspended Solid) ratio of effluent is improved by 20-60 percent, and the proportion of a high-quality carbon source is improved while the content of the suspended solid inorganic components is obviously reduced, which is beneficial to improving the capability of the subsequent processes on sludge activation as well as dephosphorization and denitrification. The invention has the advantages of convenient implementation, simple operation and management, flexible process adjustment and obvious effect.

Description

Technical field: [0001] The invention relates to a pretreatment system and a treatment method of urban sewage, in particular to a primary sedimentation fermentation pretreatment method and a treatment system for improving the phosphorus and nitrogen removal performance of urban sewage. Background technique: [0002] The pollutant removal objects and discharge control indicators of urban sewage treatment plants mainly include chemical oxygen demand (COD), biochemical oxygen demand (BOD 5 ), suspended solids (SS), ammonia nitrogen (NH 3 -N), total nitrogen (TN) and total phosphorus (TP). According to Announcement No. 21 issued by the State Environmental Protection Administration in 2006, Article 4.1.2.2 of "Pollutant Discharge Standards for Urban Sewage Treatment Plants" (GB 18918-2002) was revised to "The discharge of effluent from urban sewage treatment plants into the national and provincial determination For key river basins and closed and semi-enclosed waters such as la...

AI Technical Summary

Problems solved by technology

However, most urban sewage treatment plants in my country have significantly lower carbon-to-nitrogen ratios in the influent, and the influent BOD 5 The / TKN ratio is only 3-4, which is significantly lower than 5-6 in developed countries, seriously affecting the ability of biological phosphorus and nitrogen removal

In the case of setting up a conventional primary sedimentation tank, due to the different removal ratios of carbon and nitrogen, the problem of low carbon-nitrogen ratio will be more prominent, and BOD 5 The / TKN ratio can be reduced to a level of 2.5-3, and the treatment efficiency of the subsequent biological phosphorus and nitrogen removal process units will be more obviously adversely affected

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