Evaluation of Nitrogen and Phosphorus removal by Stepwise feeding Activated Sludge System - using one of Taichung Municipal Wastewater Treatment Plants as example

• Main Authors: Kun-Han Wu, 吳昆翰
• Other Authors: 洪俊雄
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/56392697262456656422

碩士 === 國立中興大學 === 環境工程學系所 === 105 === Technical progress came with convience for human and medical innovation, and it thus cause significant growth of population. For this reason, environmental pollution is more and more serious. If the pollution is not treated properly, the pollutant will exceed the environment loading. To prevent this problem, EPA had elevated the effluent standard. According to the effluent standard draft, year 106, ROC, the NH3-N and Phosphrus are more strict. The standard of NH3-N is modified to 6 ppm in water resource and quality protection area, and 10 ppm in other area. And T-N and T-P are 15 ppm and 2 ppm, respectly. This study aimed at evaluation of the removal of NH3-N, T-N and T-P in one of Taichung Municiple Wastewater Treatment Plant with Biological Treatment System. The treatment method is stepwise feeding activated sludge. It’s designed quantity is 12500 CMD, and 180 ppm for BOD. However, the actual quantity is 1300 CMD, NH3-N is 35 ppm, T-P is 40 ppm. The removal efficiency of NH3-N and T-N is 85% and 64%. After evaluating the operation condition, such as BOD, DO, COD, we found the T-N had better removal efficiency as C/N ratio is above 4.5. It’s theoratical removal efficiency can be above 70%. As for the Phosphrus, the C/P ratio should be above 20 to reach better removal. For the carbon source evaluation, we suggest to use acetic acid as the external carbon source in comparison with methanol and sodium acetate. Adding external carbon source in anaerobic tank and first anoxic tank can accelerate the reaction of phosphorus release and denitrification. This study also found the designed capacity is much larger than the actual capacity. The actual BOD concentration is also lower than the designed criteria, so the treatment system is operating under lower loading condition. Another issue is that the mechanical equipments are designed in fully capacity, it also causes over aeration in activated sludge tank, and thus affect the biological system.