The Experiment Study On The Biological Aerated Filter As Advanced Treatment For The Effluent From The Secondary Sedimentation Tank

Water shortages and pollution has been the limiting factor for sustainable development ofsociety with the rapid development of our economy and the constantly improvement of people’sliving standards, therefor it has become necessary to put forword new wastewater treamenttechnologies, which is simple,efficient,low consumption.This subject adpated Biological AeratedFilter （BAF） to deep treat the effulent from the secondary sedimentation tank,which would meetthe resuse standards.The results showed that using artificial vaccination method is feasible,the two filters weresuccessfully inoculated almost the same,the start-up time of the ceramsite column was20daysand the charcoal column was22days when taking into account the removal effect of COD andNH3-N.The best optimal operation parameters of the two-stage BAF were: hydraulic load0.3m3/m2·h and HRT of6h, the first reactor air/water ratio of3:1,the secondary one of1:1.Underthis condition,the average COD、NH₃-N and turbidity removal rates of the two-stage BAF were84.72%、83.13%、89.87%respectively,and the average effluent concentration were7.37mg/L、3.11mg/L、1.1NTU respectively,while the effluent quality could meet the standards of urbanmiscellaneous water. The ceramsite column play a major role in the removal of COD,and thedegradation of NH₃-N mainly occurred in the charcoal column. The average removal rate of TNwas61.36%, which provided that simultaneous nitrification and denitrification had happened inthe reactor.The removal of TP was less effective and unstable,the average removal rate was29.63%.The way of the filters bachwashing adpated air-water combination method.The backwashparameters were summarized as follows:first,the single air-flow intensity of the two reactor were10L/（s·m²）、8L/（s·m²） respectively,time was3min;second,mixing backwash,the air-flowintensity was the same as before,the water-flow intensity of the two reactor were8L/（s·m²）、5L/（s·m²） respectively, time was10min;finally,the single water-flow intensity of the two reactorwere8L/（s·m²）、6L/（s·m²） respectively,time was6min.The results showed that air-watercombination method could save energy to a certain extent and the filters had a good effect in thiscondition.