YANG Mo,LIU Mao,DENG Tao,et al.Advanced Treatment of Effluent from Secondary Sedimentation Tank of A2O Process by Coagulation–Dissolved Air Flotation–Filtration[J].China Water & Wastewater,2020,36(19 19):89-94.
Advanced Treatment of Effluent from Secondary Sedimentation Tank of A2O Process by Coagulation–Dissolved Air Flotation–Filtration
China Water & Wastewater[ISSN:1000-4062/CN:12-1073/TU]
volume:
第36卷
Number:
19 19
Page:
89-94
Column:
Date of publication:
2020-10-01
- Keywords:
- effluent from secondary sedimentation tank; A2O process; advanced treatment; coagulation; dissolved air flotation; filtration; recycling ratio; coagulant dosage
- Abstract:
- A pilot study on advanced treatment process of coagulation-dissolved air flotation (DAF)-filtration was carried out in a wastewater treatment plant in Wuhan，and its influent was secondary sedimentation tank effluent of an A2O process. When surface load was 8-12 m3/(m2·h), COD in the effluent of the advanced process was 17 mg/L, turbidity and TP in the effluent of the advanced process were less than 0.5 NTU and 0.1 mg/L. Surface load had little effect on effluent quality. The optimum operational condition was obtained when the recycling ratio was 15% and the dosage of coagulant (polymeric aluminum ferric sulfate) was 10 mg/L, and removal rates of turbidity, COD and TP were 94%, 63% and 90%, respectively. When recycling ratio was relatively small (10%), increasing coagulant dosage could reduce turbidity and COD in the effluent. When recycling ratio was large (20%), the coagulant dosage was no longer a limiting factor, and it had little impact on turbidity and COD in the effluent. In this process, coagulation-DAF process removed most of the suspended solids, turbidity and COD, in which good filtration efficiency and longer filtration cycle were obtained. This process achieved better treatment efficiency than the existing advanced treatment process of high-density sedimentation tank and precision filter.
Last Update:
2020-10-01