Comparative study of COD removal and nitrification efficiencies in single and two-stage BAF processes
单级与二级BAF工艺除碳硝化效能的对比研究

In order to investigate COD removal and nitrification efficiencies in single(C/N) and two-stage BAF(C+N) processes for treating domestic wastewater,two parallel operated BAF processes were carried out under the same aeration rate,HRT,temperature and influent wastewater quality.The results showed that the separation of COD removal and nitrification led to higher treatment performance than single-stage BAF process.BAF C had higher organic removal loading rate than BAF C/N,and the effluent COD concentration was stably lower than 50 mg/L.The effluent NH+4-N concentration of BAF C/N and BAF C+N processes were 5～12 mg/L and lower than 5 mg/L,respectively,and nitrification occurred in BAF N at pH<6.3.The lower part of BAF N had highly microbial activity,the average specific oxygen uptake rate(SOUR) was 32 mg O2/(g VAS·h).Backwash of BAF C was the same as BAF C/N,while the backwash intervals of BAF N was extended to 5～7 days,which may reduce the energy and water consumption.