Optimization Of Rural Domestic Sewage Nitrogen And Phosphorus Removal Process Based On Infiltration Silter System Of Chaohu Lake Polder In The Fall And Winter

The fugitive emission of rural domestic sewage was serious to natued bodies pollution. Excess nitrogen and phosphorus nutrients were the main reason of Chaohu lake eutrophication problem while the rural domestic sewage of Chaohu polder area, discharged at will, was an important part of its non-point sources pollution. Subsurface infiltration system, as a land treatment system, has a great potential for rural sewage treatment. Therefore, this research provide parctice basis and experiment of rural sewage treatment by exploring nitrogen and phosphorus removal process optimization of subsurface infiltration system.In this study, the domestic sewage in fall and winter of Chaohu polder area country was chosen to be the research object, nitrogen and phosphorus removal in autumn and winter process optimization research was based on the pilot project to conduct follow major conclusions. Firstly, all the experiments were completed from September to January next year that the fall and winter, the influent ammonia, total nitrogen and total phosphorus concentrations were 0.32mg/L,2.29mg/L and 0.25mg/L on average, respectively which belong to the national bad grade V. Secondly, the pilot process kept a high removal rate of nitrogen and phosphorus still when daily mean temperature was 2℃ low temperature, that TN 58.46% and TP 64.88% higher than 30%～50% of others afer the pocess optimization. Thirdly, reed clastic mixed soil, wormwood clastic mixed soiled, bluegrass clastic mixed soiled, cattails clastic mixed soiled and cattail and sludge mixed soiled were regarded as four matrix composite in matix selection experiment to choose the optium matrix composite through the analysisi of nitrogen and phosphorus removal rate in the running process, and the result showed that when the cattails matrix group was selected, total nitrogen removal could reach the highest. Fourthly, in the C/N/P operation experiment from late September to October, the addition of carbon source(glucose) according to the ratio of 50:5:1,1005:1,1505:1,2005:1 and 2505:1 displayed the promotion of total nitrogen removal and the ammonia nitrogen removal rate of 100% when 1505:1, the main cause were that adding organic carbon source could provide sufficient carbon source for denitrification. Besieds, in the next month, the residencetime operation experiment were set to 1h,2h,5h,8h and 15h respectively and found that nitrogen and phosphorus removal rate to be the higest as 5h, the ammonia nitrogen, total nitrogen, total phosphorus removal rates were 96%,85% and 76%. Last, the test set up 0cm,20cm,40cm,75cm,90cm and 95cm for water level control from early December to January next following, it displaed that the effluent water level ofbetter total nitrogen removal rate between 20cm to 95cm which were matrix layer for landfill, the average removal rate of ammonia nitrogen, total nitrogen and total phosphorus were 91%,74% and 68%.Above all, operating conditions in autumn and winter of the highest comprehensive removal of nitrogen and phosphorus was:cattail group matrix, the optimal ratio of carbon to nitrogen and phosphorus was 150:5:1, the optimal residence time was 5 hours, the best water level was 20～95cm; At this time,the removal of ammonia nitrogen,TN and TP were up to 100%,90.10% and 84.71%. And then, the lowest effluent concentration of them were 0-0.02mg/L,0.34-0.72mg/L and 0.04-0.05mg/L which belong to the national grade Ⅲ.