Study On Application Of Biological Aerated Filter In Wastewater Reuse And Reclamation

In this thesis, Application of biological aerated filter (BAF) in secondary effluent advanced treatment for reuse and reclamation is studied. It mainly includes aspects as follows: (1) Media select. Comparing the performance of biofilm growth and pollutants removal of ceramics, quartzite, zeolite and coke, results show that ceramics is better than others. (2) Start-up manner select. Comparing the performance of directly passing the process water with working flow rate, directly passing the process water with gradually increasing flow rate, and using activated sludge as seed, results show that start-up manner of directly passing the process water with working flow rate is better than others, and very suitable for wastewater advanced treatment, which has shorter start-up time, better biofilm growth state. (3) Treatment capacity analysis. The performance of BAF in COD, turbidity, NH3-N, SS removal and its influence factors are all studied, results show these: ceramics size is 2～4mm, when media height is 2m ,under the hydraulic loading of 1.8m3/(m2﹒h),the treatment effluent for upflow BAF can meet Scenic Water Quality Standard; When media height is 2.3m, under the hydraulic loading of 6.4m3/(m2﹒h),the treatment effluent for downflow BAF can meet Miscellaneous Domestic Water Quality Standard. (4) Backwash. The method, intensity, and period of backwash are all discussed, results show that the method of firstly air scouring, then air-water backwash, finally water-wash has many advantages over other methods. Backwash period is relative to water quality, inlet manner and hydraulic loading, etc. Backwash parameters are summarized as these: single air scouring intensity is 10～12L/(m2﹒s), last time is 3min; thenair intensity, water intensity and last time for air-water backwash is 10～12L/(m2﹒s), 7 L/(m2﹒s) and 6min respectively; finally water-wash intensity is 9 L/(m2﹒s), last time is 5min.