Study On Enhanced Aeration Bio-filter For Rural Domestic Sewage Treatment

At present,the rural revitalization is facing the problem of rural sewage treatment.The rural domestic sewage treatment system that has been built in China generally has problems such as out of reality,poor process selection and lack of professional management,etc.Finally it has to be shut down due to complicated operation management or high operating costs.This study returned to the traditional sewage treatment process,based on the A/O process and the biological filter to propose a rural domestic sewage treatment device.It has the characteristics of stable treatment effect,simple management and operation,low processing cost.The whole operation energy consumption is only one small power sewage pump.This study took the domestic sewage of Hanzhuang Village,Pingyi County in Henan Province as an example.During this period,the experiment examined the changes of COD and ammonia nitrogen during microbial growth and investigated the change of COD and ammonia nitrogen along the filter layer.The experiment focused on the oxygenation effect of bio-filter and its influencing factors,and studied the removal effect of COD,ammonia nitrogen,TN and TP during the stable operation period of the test device.The results show that the natural membrane should be used under the condition of average water temperature of 25?,and the membrane circulation period of the bio-filter is about 25 d.The heterotrophic bacteria are mainly distributed in the upper part of the filter layer,but the nitrifying bacteria are mainly distributed in the middle and lower parts of the filter layer.The dissolved oxygen concentration in the water gradually increases along the filter layer.Under high hydraulic load conditions,the dissolved oxygen of each filter layer is lower than that under low hydraulic load,but it can still meet the normal growth and nitrification of microorganisms in the filter layer.The average concentrations of COD,ammonia nitrogen,TN and TP in influent water during stable operation were 450,27.6,33.63 and 9.38mg/L,respectively.The average effluent concentration were 79.6,5.1,12.4 and 4.50mg/L,respectively.The average removal rates were82.24,81.52,63.07 and 52.02%,respectively.The test device had outstanding removal effect.According to the analysis of the test results,the hydraulic load of the test device should be kept between 3~5m3/m2·d,and the reflux ratio should be kept at 300%.The operating cost is only 0.34 yuan/ton,which is economical and practical.It is worth promoting in a large scale.