| In order to achieve the purpose of reuse, the secondary treatment water in the sewage treatment plant need tertiary treatment. The sewage after secondary treatment is used as a source of renewable water, the water indicators are:COD:35～55 mg/L, BOD5:10-20 mg/L, SS:10-20mg/L, NH3-N≤15mg/L, TN≤20mg/L。According to Low water carbon source and poor Biodegradability of the wastewater in the treatment plant, this paper puts forward three craft project, A/O+D-type filter, BAF+UF, MBR. With three aspects of process weaknesses, pollutants removal rate, and economic being comprehensively compared, we finally choose BAF+UF process and defined the process parameters.The advantages of BAF+UF process as follows:1. High organic load capacity, high hydraulic load, short hydraulic retention time and high water production quality;2. Requires a small amount of Area and low infrastructure investment;3.Easy to start-up and start flexiblely, It can be built as a closed plant, with no bad smell and less air pollution;4. Strong resistance to impact load ability and low temperature, no sludge bulking problem.In this paper, BAF+UF has an higher efficiency in denitrification and lower turbidity of product water. It still has a positive effect on removing Ammonia nitrogen in low temperature. Subsequent UF can guarantee the stability of water-supply; The removal rate of the target COD, BOD5, NH3-N, SS is respectively 80%,95.9% to 99.3%,92%,93.75% to 99.9%.This meet the requirements of small amount of occupied area, low infrastructure costs, low carbon sources, denitrification, stable treatment effect of water quality and quantity, thus make both the energy saving, emission reduction of sewage treatment plant, power plant and the water resources recycling possible.
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