Study On Packing Screening For Phosphorus Removal And Rural Domestic Sewage Treatment In Biofilter

With the rapid economic development of China, the rural domestic sewage treatment has already become one of the most concerned environmental problems by government and the public. Research on packing selection for phosphorous removal and biofilter processing of rural domestic sewage were inveatigated in this project, in order to provide reference for practical engineering application in rural domestic sewage treatment by biofilter.In the static adsorption experiment, after oscillating for 60h at 30℃, the concentration of phosphorus in 200 mL simulated sewage decreased from 5 mg-L"1 to below 1 mg·L-1 by adding 3 g aerated concrete particles or 7 g steel slag. Packings had the better capability of adsorption under alkaline condition. Increasing original concentration of TP in solution was able to increase Packings'adsorption quantity. The isothermal adsorption curve of aerated concrete particles matched well with Freundlich adsorption model but not so compatible with Langmuir adsorption model, while the isothermal adsorption curve of steel slag and shale matched well with both models.Pure steel slag had the best phosphorus removal efficiency under different hydraulic retention time and initial pH value, concentration of phosphorus; Except for the combined packing of steel slag and aerated concrete particle, all other kinds of combination of packings almost had the same phosphorus removal efficiency. Considering the efficiency and cost effectiveness, it was suitable to choose the steel slag, aerated concrete particles and shale combined packing when constructing the biofilter and the volume ratio of steel slag, aerated concrete particles and shale was 1:1:1.Throughout the biofilter start-up operation stage, the removal rate of TP basically remained at 86%. In the stable operation stage, the removal efficiencies of CODCr, NH3-N, TN were quite good. The concentrations of CODCr, NH3-N, TN were 15.34 mg·L-1,0.63 mg·L-1,1.32 mg·L-1, the removal rates were 93.53%,91.44% and 94.43% in intermediate effluent respectively; The concentrations of CODCr, NH3-N, TN were 11.24 mg·L-1,0.32 mg·L-1,1.14 mg·L-1, the removal rates were 95.26%,97.13% and 92.62% in final effluent respectively.Considering the two cases of the actual engineering situation and operation of rural domestic sewage treatment by biological filter, when the optimal DO is 0.5 mg·L-1, under this condition, the removal rates of CODCr, NH3-N, TN and TP achieved 76.94%,5.91%,84.62% and 85.47% respectively; when the optimal HRT is 12h, the removal rates of CODCr, NH3-N, TN and TP were up to 93.13%,81.45%,82.77% and 94.30% respectively; when the optimal C:N is 10:1, the removal rates of CODCr, NH3-N, TN and TP were up to 87.88%,92.55%,84.62% and 86.57% respectively.