| According to statistics, China produces more than8billion tons rural sewage per year, however, the rural sewage treatment system facilities is relatively lag. The unordered emission of rural sewage had caused serious water pollution in rural areas, therefore the sewage purification and treatment is a matter of great urgency. Among all the technologies, biological trickling filter has a series of advantages, such as low energy consumption, low operation cost, simple management, convenient maintenance and a certain ability to resist impact load. A lot of researches had confirmed that biological trickling filter have a good performance of the removal of COD and SS in sewage, but the common biological trickling filter has lots of disadvantages, such as easy jam, the limited ability for nitrogen and phosphorus removal,instability and insanitation. Thus researchers have focused on the improvements of biological trickling filter to enhance the ability of nitrogen and phosphorus removal.In order to improve the efficiency of novel multi-layered biological tricking filter for nitrogen and phosphorus removal and solve the difficult of the water treatment for rural wastewater,different process variables of layered biological trickling filter was studied.It is expected that these tests will supply practical reference for the efficient treatment for the rural water. Four key factors were studied which were different filter material, different reflux ratio, hydraulic load and seasons during the process of water treatment. The performance of the noval layered biological trickling filter had been systematically studied under different process conditions for the removal of nitrogen and phosphorus in wastewater. The pH value, the concentration of the NH4+-N, TP, TN, COD in the process were observed, so as to determine the optimal parameters. In addition, UBF anaerobic technology-the layered biological trickling filter had been carried out to examine the effects for nitrogen and phosphorus removal.The study shows that:(1) The impact of different filter material on the performance of the nitrogen and phosphorus removal of layered biological trickling filter was carried out with synthetic rural domestic sewage. The results shows that the period of reaching the stability state of the various indicators for three kinds of filter material composite resin, air brick and slag are longer at startup phase during the winter. All the indicators can quickly achieve stability when the device restarts in spring. Slag and air brick have a good performance for ammonia nitrogen removal due to its large specific surface area, the removal rate was84.22%and86.50%respectively. But the ammonia nitrogen removal rate of the air brick is very low in winter, low temperature have a great impact on air brick’s performance. TP removal rate of three kinds of filter material gradually reduce as the operation goes on. TP removal rate of the air brick and the slag reached64.71%and61.56%respectively, but the phosphorus removal of the air brick is also affected by the low temperature in winter. The TN removal rate of composite resin, slag and air brick were52.80%,43.01%and31.49%respectively. The COD removal rate of composite resin, slag and air brick were around70%. The slag was selected to be the best test filter material after comprehensive consideration.(2) The impact of different hydraulic load on the performance of the nitrogen and phosphorus removal of layered biological trickling filter was carried out with synthetic rural domestic sewage. The results shows that the removal rate of TN, TP decreased with the increase of hydraulic load, the removal rate of TN and TP reaches the highest under the condition of hydraulic load at4m3/m2.d-1, the average removal rate were57.37%and64.18%respectively. The removal rate of NH4+-N and COD reaches the highest under the condition of hydraulic load at6m3/m2.d-1, the average removal rate were80.94%and68.80%respectively. (3) The impact of different the reflux ratio on the performance of the nitrogen and phosphorus removal of layered biological trickling filter was carried out with synthetic rural domestic sewage. The results shows that the best reflux ratio of layered trickling filter for ammonia nitrogen, TP, TN,COD removal were1:1,2:1,2:1,1:1, respectively, the average removal rate were87.08%,66.04%,56.02%and80.78%respectively. Adopting high reflux ratio is an efficient way to enhance the ability of the nitrogen removal for trickling filter.(4) The impact of different seasons on the performance of the nitrogen and phosphorus removal of layered biological trickling filter was carried out with synthetic rural domestic sewage. The results shows that the layered biological trickling filter operate stability. It has good treatment effect on the removal of TP and COD, ammonia nitrogen, but it is not suitable to TN removal. TN, TP and ammonia nitrogen removal rate reduced at the later stage of the operation.(5) The study of nitrogen and phosphorus removal of the layered biological trickling filter-UBF technology was carried out for with synthetic rural domestic sewage. The result shows that the removal of ammonia nitrogen, total phosphorus and COD are very significant, the average removal rate reached60%,50%and85%respectively, and the PH value of the sewage effluent was stable at8. But the TN removal rate is only less than30%. |
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