ABSTRACT
This project is a primary design of sewage plant of economic area in a of Danyang. The treated wastewater is typical municipal sewage. The design scale is 2000m 3 /d and the total area of the sewage plant is about 3500m2 . The primary water quality is presented as following: BOD5 = 200mg/L，COD = 300 mg/L，SS = 300mg/L，TN = 67mg/L，NH3-N = 45mg/L，TP = 2.2mg/L；and the effluent need reach the Grade B Standards in 《Emission Standards of Urban sewage treatment plant》 GB8978-2002, which is BOD5 ≤20 mg/L，COD≤ 60mg/L， SS ≤ 20mg/L，TN ≤20mg/L，NH3 -N≤8mg/L，TP ≤1mg/.
Through the comparison of activated sludge process in domestic and abroad, I finally choosing improved oxidation ditch process as sewage treatment process. This process increases an anaerobic pond before the Carrousel 2000 oxidation ditch, forming a combined biochemical pool. This method can not only meet the requirements of sewage nitrogen and phosphorous removal, but also consistent with the current water quality status of the film area.
The wastewater treatment process: sewage→medium space grid→sewage promote pump→thin grid→flat flow grit chamber→water distribution well→ anaerobic tank→oxidation ditch→vertical flow sedimentation tank→ultraviolet disinfection→discharge water.
The sludge treatment process: sludge pumping station→sludge thickening tank→sludge storage tanks→dewatering room→ sludge output.
Key words: municipal sewage; improved oxidation ditch; nitrogen and phosphorous removal; sludge treatment
