Experimental Study On BAF With Post-denitrification To Treat Wastewater

This article aim at the poor effect of the denitrification and phosphorus removal in thecurrent residential sewage treatment process, choose biological aerated filters with manyadvantages-small floor area, low energy consumption and high-quality water to treat wastewater,and then improve it and use the post-denitrifying biological aerated filters technology to improvethe quality of effluent water. First, the experiment adopt the two-stage bamboo charcoalbiological up-flow aerated filters to do the experimental study and theoretical analysis,investigate its removal efficiency and discuss the influence of air water volume ratio, hydraulicretention time and temperature,etc on the pollutant removal performance; and then, through theimprovement device, confirm the superiority of post-denitrifying device, and by using theorthogonal experiments to determine the optimum condition and removal performance of thepost-denitrifying biological aerated filters.With bamboo charcoal for packing, the two levels of biological aerated filters andpost-denitrifying biological aerated filters have good effect in the contamination removal, andthe latter is more better on the removal efficiency of TN. The results show as follow:(1) The optimum conditions of two-stage bamboo charcoal BAF is: the hydraulic loadingis0.5m3/(m2·h), the first air water volume ratio is4:1, the second air water volume ratio is1:1. Inthese conditions, COD, ammonia nitrogen, SS, TN, TP removal rate are respectively87.32%,76.39%,90.32%,43.19%and23.06%, the concentration of raw water are as follows:334.07mg/L,33.67mg/L,99.58mg/L,59.25mg/L and6.30mg/L, the concentration of effluent are42.36mg/L,7.95mg/L,9.64mg/L,33.66mg/L and4.85mg/L. In addition to the concentrationof TN and TP are too high, the others can be directly emissions.(2) The optimum conditions of post-denitrifying BAF is: the hydraulic loading is0.5m3/(m2·h), the air water volume ratio is4:1, C/N ratio is4:1, anaerobic zone height is0.6m.In these conditions, the removal rate of COD, ammonia nitrogen, SS, TN, TP are85.81%,74.86%,91.30%,71.35%and33.22%, the concentration of raw water are as follows:318.90mg/L,31.17mg/L,100.38mg/L,44.19mg/L,5.78mg/L, and the effluent are respectively:8.73mg/L,45.25mg/L,7.84mg/L,12.66mg/L,3.86mg/L. Among them, TP is not conform to theemissions standards, the other pollutants are achieve the A standards.The results show that: the above devices both have a good removal efficiency of COD, SS,ammonia nitrogen, and is suitable for treating sewage; with the carbon source, the removal rateof TN improve; the effect of TP is unsatisfactory, and more corresponding chemical phosphorusremoval process are needed.