Application Of Enhanced Biological Phosphorus Removal In Mobile Wastewater

The use of synthetic detergents, fertilizers and pesticides increases with the continuing industrialization and urbanization of China, and this is accompanied by release of large amount of phosphorus into the aqueous system. The resulted eutrphication of water presents a growing risk to the environment. Therefore, the removal of phosphorus is important in sewage treatment. Due to its unique advantages, biological removal of phosphorus received intensive attention.The automobile manufacturing process produces multiple types of wastewater and some of them present high phosphorus content. Chemical removal is commonly used for treating these wastewaters but suffers from disadvantages of high cost, creation of sludge and potential secondary pollution. Biological removal has been proposed as a new technique to overcome these problems. However, since the automobile wastewaters typically have low BOD5, the performance of biological removal process needs to be optimized.In this research, wastewaters from an automobile manufacturing plant were subjected to the SBR removal process. The processing cycle is 9.5h and the parameters were experimentally determined to be: rapid water feed, anaerobic stirring (2h), aeration (6h), precipitating (1h), discharge of water and sludge (0.5h). The changes of pollutants in water were monitored and their removal mechanisms were analyzed. The effect of parameters such as pH, temperature, and additional carbon sources were also investigated in this study.The following conclusions were achieved from the present study: 1. When appropriate MLSS and TP removal rate are maintained, the optimal sludge age is 12 days.2. Increasing the system pH to 8 can significantly enhance absorption ofphosphorus.3. The optimal TP concentration of the original wastewater is about 6 mg/L.4. Anaerobic stirring should be adopted at the anaerobic reaction step to improve the final TP removal rate.5. Quick increase of DO concentration during the first 0.5 h can improve the absorption rate of phosphorus.6. Change of temperature, within the range of the present study, has little effect on phosphorus removal.7. Addition of organic material at the early stage of the anaerobic reaction is essential for biological removal of phosphorus from automobile manufacturing wastewaters.8. When the concentrations of COD: 422 mg/L, TP: 6.7 mg/L and NH3-N: 28 mg/L, the effluent concentrations are reduced to 50 mg/L, 0.8 mg/L and 4.8 mg/L, or corresponding removal rates of 88.2%, 88.0% and 82.8%, respectively. The effluent meets the class 1 standard.