Experiment And Project Application Of Light Medium-Biological Aerated Filter

Two stage up-flow biological aerated filters with modified polystyrene have been used in experiment, and oxygenation capacity, biofilm attachment and the effect of sanitary waste treatment are analyzed. The results show that: medium can improve the oxygen transfer rate and oxygen utilization rate of BAF. The oxygen transfer rate of BAF with 30% packing ratio is 30%~70% larger than with no medium. The oxygen transfer rate of BAF with 60% packing ratio is begin fall, but it's still larger than with no medium. Polystyrene medium is easy to be attached by biofilm, and the period of biofilm attachment is only 13 days. Both of the stability and average removal rate of the former's are better than the latter's.COD and turbidity are removed well by two-stage biological aerated filters. The effluent COD of primary reactor below 100mg/L except especial condition; the average and the maximum removal of COD are 68.09% and 90.53%. The effluent COD of secondary reactor below 60mg/L. Total removal and the maximum removal of COD are 77.75% and 91.39%. The average turbidity removal of primary reactor is 80.54%, and total removal rate is 87.52%. Besides, the effluent ammonia nitrogen is stable and the average removal is 79.68% in the condition that the influent ammonia nitrogen is less than 35mg/L; or else, the removal of it fall evidently.Gas-water bachwash is effective for biological aerated filter. The effluent can recovery to normal in one hour and a half, and the effluent COD and turbidity are below 60mg/L and 10NTU respectively. The removal of ammonia nitrogen is little affected by bachwash process.Besides, a set of intergrated equipment has been manufactured and used in Reclaimed Water Project of Tianjin Cancer Institute and Hospital, the main section of which is biological aerated filter using ceramisite medium. After debug and operate, effluent meets the requirement of The Reuse of Urban Recycling Water-Water Quality Standard for Urban Miscellaneous Water Comsumpution (Flushing Water) of GB/T18920-2002, according to examination results of Tianjin Drainage Monitoring Station. This project has acquired good econmic effects and society effects.