Study On The Effects Of The Operational Process Of Biological Aerated Filter

Biological aerated filter has been widely used and extended in China,in this text,we concerned about the actual situation of three sewage treatment plant which usebiological aerated filter process in the western, southern and central of Daqing,wediscussed some influencing factors including backwashing、concentration of dissolvedoxygen、temperature and biofilm of the biofilter during operation. The achievementof the study as follows：（1）Though carrying out the First-degree BiologicalAerated Filter backwash schememade by backwash experimental in central wastewater treatment plant， the timerequired for flushing a pond reduced from4hours to1hour and10minutes，and thesurface appearance of water improved greatly，the degree of uniformity of gasdistribution have been improved significantly too，the extent of anaerobic has beenreduced greatly，the removal rate of COD improved by8.04％；suspended solidsimproved by15.52％.（2）The gas and water mixing ratio of first-degree biological aerated filter Should becontrolled in3.5:1~4:1，the gas and water mixing ratio of second-degree biologicalaerated filter Should be controlled in3.5:1~5:1, we can make the concentration ofdissolved oxygen of first-degree biological aerated filter controlled in3mg/L~3.5mg/L and second-degree biological aerated filter controlled in2.5mg/L~3mg/L, at this moment, the removal rate of COD and ammonia nitrogen offirst-degree and second-degree biological aerated filter can be above70%,the effect ofthis treatment is betrer. we get the scheme of the fan operations of biological aeratedfilter in the sewage treatment plant of southern district though calculation and the actual inspection, which can ensure the concentration of dissolved oxygen in theoptimal operating range, at the same time,the amount of aeration is appropriate, inorder to energy-saving.（3）The effect of temperature on the biological aerated filter is very significant, whenthe temperature decreases, the removal rate of COD and ammonia nitrogen decreased,the level of biological aerated filter control dropped significantly. Therefore, in orderto reduce the impact of temperature on the process of running, we developed fivemeasures based on the management experience of the actual operation of biologicalaerated filter:①、Strengthen the level of pretreatment. and make the water qualitybetter and reduce the load to increase its processing capacity；②、We improve theaeration quantity of fans appropriately to optimize the quality of the environment inorder to increase the growth speed of microbial；③、When the aeration tank running ingood condition,we can reduce the cycle of backwash, so that we can avoid the loss ofmicrobial brought by the backwash, reduce the recovery time after backwashing；④、We could also use the advanced treatment process to ensure the quality of finaleffluent；⑤、In winter,we can add structures to keep the Biological Aerated Filterwarm.For example,we can use the plastic shed over the top.（4）Though the biological microscopy, we could see that the best time to biofilm isstable period, we can see many species and quantity metazoan though the microscope,the composition of the whole microbial tends to relatively stable. Therefore, theremoval rate of COD has remained at a high level(above70％)，when we see thebiological aerated filter, we can feel it is relatively clear, and it can maintain a goodtreatment effect and operating status.