ABSTRACT
The major process of the design is that CASS technique was adopted for treating the Domestic Sewage. The CASS process ( Circular activated sludge ) is intermittent activated sludge process that well combines a activated sludge who will be variable volume with biological selector principle, and it has the characteristics of nutrients removal and phosphorus removal, and it operates the way sequencing batch aeration and the aeration.This design is simple and orderly on the general layout. It sets two grilles in the inlet, they remove mainly the larger floaters and suspended solids in the sewage; And then, It sets two sink sand pools, they remove mainly the little inorganic particles; It also sets flocculation reaction pool, It uses chemical processing methodes and moves mainly the SS in the sewage; And this design sets CASS technique as the major process of biological treatment method which removes mainly the organics in the sewage.Effluent quality can met the requirements of the GB 18918-2002 Standard for Discharge of Pollutants from Sewage Treatment Works in Towns and Cities IB. This paper Mainly introduces the advantages and disadvantages of CASS technique, the comparison of CASS technology and other biological treatment processes, It designs the process of sewage treatment and the size of each poolbody according to the yield of water and quality of water. The article makes the calculation of elevation and analysis of effectiveness.
Keywords:CASS technique; treating domestic sewage; process design
第一章总论
1.1主要内容：
要求通过对城市污水进、出水水质的研究，根据总体规划和设计资料，充分利用所学知识和现有条件，采用CASS法处理6万吨城市污水，出水要求达到污水综合排放标准的二级标准
处理量：5万吨 /d 进水：COD＝400mg/L；BOD=200mg/L；SS=200mg/L；