Study On Treatment Of Chemical Fiber Wastewater Using Thermophilic Anaerobic-mesophilic Aerobic Coupling System

The components of chemical fiber wastewater are very complicated and vary much seriously. The concentrations of COD and NH3-N contained in chemical fiber wastewater are very high. So chemical fiber wastewater is very difficult to be treated using traditional methods. In this paper, a new system by using coupling of moderate temperature and high temperature was applied in treating wastewater with high concentration of chemical fiber and a better result was obtained finally.Firstly, the aerobic activated sludge of moderate temperature was acclimated through gradient culture in a batch reactor into anaerobic activated sludge under high temperature. Secondly, the anaerobic activated sludge was introduced into a stirred tank reactor and was cultured continuously to treat real wastewater from chemical fiber factory. The effects of different operating parameters on treating wastewater were conducted and the optimum operating conditions were obtained finally. The results showed that under the optimum operating conditions (temperature = 55 ℃, influent pH = 5.3,HRT = 18 h, activated carbon as carrier), the removal efficiency of COD and NH3-N were 83.3 % and 31.7 %, respectively. The concentration of COD and NH3-N contained in effluent were 548.6 mg/L and 121.9 mg/L, respectively. As can be seen from these, the feasibility of biodegradation was enhanced and the expected results were obtained by the first stage anaerobic treatment under high temperature.Then the effluent from the stirred tank reactor was introduced into an airlift loop reactor and was treated for the second stage under high temperature. The effects of two different carriers and some operating parameters on the treatment efficiency were conducted. The results showed that the effluent concentration of COD and NH3-N was 69.0 mg/L and 17.4 mg/L, respectively, when temperature was 35 ℃, influent pH was 7.5, the gas Flux was 0.075 m3/h and HRT was 8 h . The effluent concentration of COD and NH3-N reached the first level effluent standard of China (COD≤150mg/L,NH3-N≤25mg/L).The system by coupling of high temperature and moderate temperature was considered and optimized. The results showed that the system could work favorably and the effluent concentration of COD and NH3-N reached the first level effluent standard of China when the volume of the stirred tank reactor was 1 L and the volume of the airlift loop reactor was 4.2 L.