Optimization Of Multi-layered Bio-Tricking Filter Process In Treating Domestic Sewage-Enhanced Nitrogen And Phosphorus Removal

Water pollution is becoming more and more serious along with further development of the acceleration of urbanization in our country, so it’s meaningful to find a economic way for dealing with the problem of country domestic sewage.Owing to less capital investment, low power consumption, less sludge production, biotrickling filter have been used in domestic sewage treatment.According to numerous studies abroad: as a decontamination process,bio-trickling filter relies on biofilm.Through proper packing,reactor design and relying on natural ventilation oxygen, it can greatly improve nitrifying bacteria dwell time in the system.So the removal of pollutants in sewage is good, which can be realized on nitrogen and phosphorus removal under low-energy conditions of rural sewage treatment.The study which uses multi-layered bio-tricking filter process in treating campus sewage mainly divided into two phases. First, we use single-stage parallel combination of biological trickling filter to clear campus sewage and study hydraulic loading,packing type, water distribution cycle,A/O +reflux and and other factors on the influence of the treatment,which can help us get the Optimum operating condition;Second,we use two-stage A/O bio-trickling filter to study the reflux ratio on the treatment effect, strengthening the system nitrogen and phosphorus removal. The main results are as follows:(1) In the study of mixed packing bio-trickling filter’s biofilm properties,two mixed packing bio-trickling filter basically have the same speed of biofilm growth,but in terms of the effect of domestic sewage treatment, clinoptilolite +coke mixed packing bio-trickling filter is better than clinoptilolite + blue carbon mixed packingbio-trickling filter.(2)In two different mixed packing bio-trickling filter comparative test, their best hydraulic loading are 0.6m3/(m2·d). Respectively, the average removal rate of COD,ammonia nitrogen, TN and TP were83.3% 、 86.52% 、 23.93% and 60.48% for clinoptilolite +coke mixed packing bio-trickling filter;On the other hand, the average removal rate of COD, ammonia nitrogen, TN and TPwere77.31%、86.6%、31.87% and47.51% for clinoptilolite +blue carbon mixed packing bio-trickling filter. In a word,clinoptilolite+coke mixed packing bio-trickling filter has a better removal of TP and clinoptilolite +blue carbon mixed packing bio-trickling filter is suitable for removing TN.(3)A/O+reflux structure has little effect on removal of COD, ammonia for the two mixed packing bio-trickling filter, but they have some different on removal of TN and TP.(4)Considering the pollutant removal, biofilm update and actual system operation,two mixed packing bio-trickling filters’ best water distribution cycle are 10:1. Under of the condition of best water distribution cycle, clinoptilolite+coke mixed packing bio-trickling filter and clinoptilolite +blue carbon bio-trickling filter‘s COD, ammonia nitrogen, TN and TP removal rates respectively were 83.2%, 88.7%, 26.4%, 61.6% and78.7%, 81.8%, 32.9%,47.5%.(5)Because hydraulic loading, packing types and water distribution cycle has little effect on system effluent p H, so bio-trickling filter has a certain p H control for influent.(6)In the two-stage A/O bio-trickling filter, the appropriate reflux ratio can help to remove COD, ammonia nitrogen, TN and TP in the domestic sewage. With increasing reflux ratio, the removal rate of COD, TN and TP fall after increase.The best reflux ratio were 100%, 50% and 100% and the average removal rates were 91.8%, 41.9%and 46.8%; On the other hand, the removal rate of ammonia increase in pace with increasing reflux ratio.The best reflux ratio is 200% and the average removal rate was99.67%.