Study of chemically enhanced primary treatment of wastewater received by urban rivers
- XU Chun-hua,GAO Bao-yu,LU Lei,XU Shi-ping,CAO Bai-chuan,YUE Qin-yan and ZHANG Jian
J4. 2006, 41(2):
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The chemically enhanced primary treatment of wastewater received by the Zhulong River and Baijia River in the city of Zibo, Shandong, China has been studied. According to the characteristics of the rivers, their water quality, and the wastewater received, several coagulants were selected to use in the experiments conducted at the rivers, including polyaluminum chloride (PAC), cationic polyacrylamide (CPAM), anionic polyacrylamide (APAM) and polydimethyldiallylammonium chloride (PDMDAAC). Their efficiencies for removing COD, SCOD, turbidity, NT and PT were investigated and compared. APAM and PDMDAAC were found to be the most appropriate coagulants. The impact of surface load and pH on the effectiveness of coagulation was also considered and analyzed. The results showed that at the optimum dosage of APAM (0.3?mg/L), the COD and SCOD removal efficiencies reached to 44％～64％ and 33％～67％, respectively, while at the optimum dosage of PDMDAAC (0.5?mg/L), COD and SCOD removal efficiencies were 51％～60％ and 21％～67％, respectively. Both APAM and PDMDAAC achieved a lower efficiency, 15％～20％, in removing NT, whereas they had a higher PT removal efficiency that was 60％～80％. It was found that pH had a very little effect on the efficiency of COD removal, and better coagulation could be achieved when pH was in the range of 7～10. The results also showed that there was insignificant change in COD and turbidity removal efficiency when surface load was increased from 0.8?m3/m2·h to 1.2?m3/m2·h.