Technological Research Of IC Anaerobic-Triple Oxidation Ditch For Piggery Wastewater

With the development of mechanized piggeries, environmental pollution that it brought about has become more and more serious. Conventional anaerobic processes are merely adopted by the piggeries now, so it can not meet the discharge standard of pollutants. It is difficult to treat piggery wastewater due to higher organic waste contained in it. In this paper IC anaerobic-triple oxidation ditch was adopted and process performance and treatment efficiency of triple oxidation ditch(T-ditch) treating piggery wastewater were emphasized. The main conclusions are as fellows:Firstly, piggery wastewater is treated with IC anaerobic reactor. Then the start-up of the reactor and operation efficiency are studied. It is discovered that cubage load is lower in the forepart of the start-up and overlong HRT is against the treatment efficiency of COD removal. The treatment efficiency of the different concentration in piggery wastewater is good under short HRT (HRT=5.4h, 7.6h, 9.4h) with IC anaerobic reactor, and removal rate of the COD reaches 80.85%~90.2%. The operation of IC reactor is in a good condition under 16癈, which reaches 80%.Afterward, IC anaerobically digested effluent of piggery wastewater is treated with T-ditch. T-ditch process with nitrification and denitrification can achieve a better performance in removal of COD and SS, and is reliable in operation. The removal efficiency of TN TP in the process are better than that of only combined with nitrification. The influence of the temperature, HRT and C/N to the efficiency of the denitrification operation is studied. The removal rate of COD and TN is influenced by the temperature; especially the influence of the removal rate of TN is bigger. The best HRT is 18h when IC anaerobically digested effluent is treated with T-ditch. The amount and quality of carbon source are the important factors to the denitrification.It was found that the ratio of the duration for denitrification phase and that for nitrification, tDN/t, is an important parameter to balance denitrification potential and nitrification capability. By comparing four different tDN/tN:0.17, 0.27, 0.40, 0.56, the best nitrogen removal efficiency can be achieved while tDN/tN is 0.40. The microzoon species appearing in T-ditch operation were summarized in this paper, and some characteristics of biofacies in different conditions were discussed. Some detailed suggestions for improving TN, TP removal, controlling sludge bulking, et al in operation T-ditch are provided. The mass balance equations using ASM1 and the water quality model of T-ditch are established. The simulation result shows that the variety of different water quality represents the periodicity of various degrees and the reason of the appearance of especial peak value is mainly of boundary condition. By comparing the simulation and practice result, the water quality model of T-ditch is good for prediction. .Last, the characters of IC Anaerobic-Triple Oxidation Ditch for Piggery Wastewaterare discussed. The total removal rate of the COD is 97% and the removal rate of the NH3-N is 97%. Therefore, the treated wastewater could meet the discharge standard of pollutants. By comparing the operative expense between this process and practical terms, the former have the good efficiency of treatment for simple flow, few building, low expense of operative and management et al. Finally, IC anaerobic-triple oxidation ditch is concluded.