| With the promulgation of the new effluent standers set up, the sewage treatment plant of china will face more severe challenges. A2/O is most widely used because it is the most simple activated sludge process which can remove nitrogen and phosphorus synchronously. But it has some drawbacks, such as the competition of carbon source and different sludge age. It is difficult to simultaneously in a single system for efficient removal of nitrogen and phosphorus. Therefore,the research of develop the new water treatment material, process, technology, and strengthen the existing technology of the process is particularly important. Fiber carrier A2/O process is developed by adding polyvinyl alcohol fiber to the anaerobic, anoxic and aerobic tank in a A2/O process by combining biofilm approach into conventional activated sludge process to constitute a new system. The reactor provide a more favorable living environment for different types of bacteria. This complex biofilm process also exists the phenomenon of denitrifying phosphorus removing bacteria accumulate organism in anoxic tank, it can make use of carbon source.Fiber carrier A2/O process was compared with traditional A2/O process for domestic wastewater treatment. Results show that under the same conditions the wastewater treatment performance of fiber carrier A2/O process was better than traditional A2/O process. The fiber carrier A2/O process improved the effluent COD,ammonia nitrogen and phosphorus from Grade B to Grade A. The effluent concentrations of COD, ammonia nitrogen and phosphorus were 35mg/L、3.9 mg/L、0.5 mg/L. The removal rates were kept at 91.6%～93%、92.7%～ 94%、84.5%～86%.Although both processes have reached the Grade A, the fiber carrier A2/O process TN effluent was lower than the traditional A2/O process 3.9 mg/L or more. The experiment also found in the traditional A2/O process the denitrifying phosphorus removal amount occupies 37.6% on average. In fiber carrier A2/O process this phenomenon effect is enhanced and this figure reached 48.3%. In traditional A2/O process the average removal rate of COD was 80.5% in anaerobic tank. While in fiber carrier A2/O process the average removal rate of COD was 91.7%. The anaerobic tank make a lot of COD transform to PHB enter the anoxic tank.In this study using fiber carrier A2/O process to analyze the effect of denitrifying phosphorus removal efficiency in different nitrification liquid reflux ratio. The nitrification liquid reflux ratio set up four conditions,they were 150%,200%,250%,300% to study the phosphorus release in anaerobic, phosphorus absorption in anoxic or aerobic tank. Results show that when reflux ratio reached 250% the maximum of phosphorus reach 0.723. It showed that denitrifying phosphorus removal of anoxic tank account for 72.3% of the total phosphorus removal. For denitrifying phosphorus accumulating bacteria, the maximum utilization of PHB was 1.08 g/(g/L) and had the best metabolic activity. The removal efficiencies of COD and ammonia has little influence at different reflux ratio. When nitrification liquid reflux ratio reached 250% the total nitrogen removal rate reached 91.5%.The results showed that when the reflux ratio at 250% is the best conditions. Not only organics removal effect performance well, but also promote the accumulation of denitrifying phosphorus and makes it developed.The absolute value of ORP in anaerobic tank and anoxic tank has certain relationship with releasing phosphorus in anaerobic tank and uptake phosphorus in anoxic tank. The effect can be measured by the test of ORP. |
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