Study On Denitrification By Autotrophism And Heterotrophism In Biological Aeration Filter

BAF is a wastewater treatment technology with characteristic of facility，goodeffect and low consumption. In the present study, aerobic ammonia oxidizing bacteriawhich were enriched in a SBR reactor had inoculated into biological aerated filter tostarting up, and then the running effect in different conditions was tested. Reactionmechanism and influence factors of nitrification and denitrification were studied withlimit of dissolved oxygen conditions in biological aerated filter. The wastewatertreatment effect in autotrophic and in heterotrophic condition were inspected. And aseries of studies were did about parameters and operation condition for biologicalaerated filter.The test results shows that after24days hanging film, ammonia nitrogenremoval rate in one reactor were88.8%, and were90.2%in another. It indicated thattreatment effect was good on synthetic wastewater by biological aerated filter.The effects of the layer height, reflux ratio, backwash cycle and small particlesize of fillers on the biological aerated filter had researched. The test results showsthat good result of removing ammonia nitrogen can be come true by BAF using smallparticle size ceramsite(1～2mm), but it required strict growing conditions. It alsoshows that the ammonia nitrogen removal rate was higher in the lower part than theupper filler layer. And it had the highest ammonia nitrogen removal rate when theinner recycle ratio was200%, while reflux ratio of more than300%in ammonianitrogen removal rate declined obviously. The treatment effect could be stable whenBackwash cycle was48hour.It was no obvious effect of ammonia nitrogen removal when COD under50mg/L.When COD was more than100mg/L, ammonia nitrogen removal rate was reduced,and the removal rate of COD was increased. The removal of COD mainlyconcentrated in the lower part of the filter layer, and the removal rate of COD in theupper part of the was obviously reduced. In the filtering layer, ammonia nitrogen removal are mainly concentrated in the middleand upper part, but was highest in themiddle.