Wastewater Treatment with Biological Aerated Filter Using Waste Materials-Grain Slag Media as Biofilm Support

摘要

The aim of this research was to empolder a sort of biofilm media used as biofilm support of BAF (Biological Aerated Filter). The performance of two lab-scale BAF was monitored for 6 months to compare the effect of grain-slag with haydite as media. Under ammonia nitrogen load rates varying from 0.49 to 1.21kg NH3-N·(m3· d)-1, the overall NH3-N reductions of the BAF supported by grain-slag and haydite averaged 84.30 and 80.87%, respectively. Higher ammonia nitrogen removal in the BAF with grain-slag was attributable to its buffering pH value capacity by stripping calcium carbonate (CaCO3). In terms of removing organic matter、turbidity and colourity, the efficiency of the BAF with grain-slag was lower than that with haydite, but More than 78%, 79% and 80% of fed organic matter, turbidity and colourity was still removed, respectively. So it is feasible for grain-slag to be applied as the media of BAF. The results obtained from the research of ammonia nitrogen removal rate versus pH values indicate that ammonia nitrogen removal rates were not distinctly dependent of pH values in the BAF supported by grain-slag. More than 85% of ammonia nitrogen was removed at pH values from 5.2 to 7.8 ranges. Grain-slag can strip CaCO3 into the wastewater to buffer pH value and maintain optimal nitrification rates.