Simulating Study On Using Of Sanitary Sewers As Municipal Wastewater Treatment Systems

The simulating experiment of using sanitary sewers to treat municipal wastewater was studied in the paper to develop simple, high efficient and low power-wasting treatment technology that adapted to the situation of our country.The lack of biomass in sanitary sewers was resolved by means of return-sludge flow and suspending filler. Using strengthen of pipeline aeration, wastewater flow and hydraulic drop in sanitary sewers to oxygenate, the experiment of oxygenate efficacy indicated: the oxygenate mode of hydraulic drop possess enormous popularized predominance in the engineering.The effect of flow velocity, HRT, biomass concentration and loading rate Ns on treatment efficacy in sanitary sewers was studied by means of two kinds of running state: activated sludge and bio-film process.(1) Using activated sludge in sanitary sewers process, the research result shown: when influent CODcr was 200 mg/L,MLSS was 3.0g/L, HRT was 0.5h, Nswas 3.6 kgBOD5/kgMLSS-d, when influent COD cr was 400 mg/L,MLSS was 3.0g/L, HRT was 3.0h, Nswasl.2 kgBOD5/kgMLSS-d, the effluent COD cr was less than 60mg/L, effluent BODs was less than 20mg/L and effluent SS was less than 20mg/L, which achieved the requirement of level 1 of national town wastewater discharge standard entirely.(2) Using activated sludge in sanitary sewers + bio-flocculation process, the research result shown: when influent COD cr was 600 mg/L, water temperature was 20 C, and to sewer step, Ns was 2.4 kgBOD5/kgMLSS-d, HRT was 120min, and to bio-flocculation step, Nswas 2.5 kgBOD5/kgMLSS-d, HRT was 25min, the effluent COD was less than 60mg/L, effluent BODs was less than 20mg/L and effluent SS was less than 20mg/L, which achieved the requirement of level 1 of national town wastewater discharge standard entirely.(3) The study on only using bio-film process in sanitary sewers to treat low and middle concentration municipal wastewater showed: when influent CODcr was 150~ 350 mg/L,filter volume density was 35% and HRT was 2.5-3.5h, the effluent CODcr was less than 60mg/L, effluent SS was less than 20mg/L, COD was 71.4-84.5%, SS was 86.2-88.3%, and effluent wastewater quality was good.(4) The study on using bio-film in sanitary sewers + bio-flocculation process totreat middle and high concentration municipal wastewater showed: when influent COD cr was 360~750 mg/L,filter volume density was 35%, HRT in the sewer was 2.5~3.5h, HRT and Ns of bio-flocculation process was respective 30min and 3.0 kgBODs/kgMLSS.d, the effluent CODcrwas less than 60mg/L, effluent SS was less than 20mg/L, total a COD was 91.4-93.5% and total n. ss was 89.4-94.6%.