Effects of pH on coagulation behavior and floc properties in Yellow River water treatment using ferric based coagulants  

作　　者：CAO BaiChuan GAO BaoYu XU ChunHual, FU Ying LIU Xin 

机构地区：[1]Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong Uni- versity, Jinan 250100, China [2]School of Civil and Architecture, Jinan University, Jinan 250022, China

出　　处：《Chinese Science Bulletin》2010年第14期1382-1387,共6页

基　　金：supported by the Key Projects in the National Science & Technology Pillar Program in the Eleventh Five-year Plan Period (Grant No.2006BAJ08B05);the sub-projects in the National Water Pollution Control and Government Key Special Project in the Eleventh Five-year Plan Period (Grant No.2008ZX07422-003-02)

摘　　要：Enhanced coagulation is one of the major methods to control disinfection by-products (DBPs) in water treatment process. Coagulation pH is an important factor that affects the enhanced coagulation. Recently, many studies focus on the coagulation effects and mechanisms, and few researchers studied the properties of flocs formed under different coagulation pH. Two inorganic polymer coagulants, polyferric silicate sulphate (PFSS) and polyferric sulphate (PFS), were used in Yellow River water treatment. The influence of pH on coagulation effect was investigated under the optimum dosage, and the results show that both coagulants gave excellent organism removal efficiency when pH was 5.50. According to the variation of zeta potential in coagulation process, coagulation mechanisms of the coagulants were analyzed. An on-line laser scatter instrument was used to record the development of floc sizes during the coagulation period. For PFSS, pH exerted great influence on floc growth rates but little influence on formed floc sizes. In PFS coagulation process, when pH was 4.00, PFS flocs did not reach the steady-state during the whole co-agulation period, while little difference was observed in floc formation when pH was 5.50 and above. The preformed flocs were exposed to strong shear force, and the variation of floc sizes was determined to evaluate the influence of pH on floc strength and re-growth capability. In comparison of the two coagulants, PFS flocs had higher floc strength and better recovery capability when pH was 4.00, while PFSS flocs had higher floc strength but weaker recovery capability when pH was 5.50 and above.Enhanced coagulation is one of the major methods to control disinfection by-products （DBPs） in water treatment process. Coagulation pH is an important factor that affects the enhanced coagulation. Recently, many studies focus on the coagulation effects and mechanisms, and few researchers studied the properties of flocs formed under different coagulation pH. Two inorganic polymer coagulants, polyferric silicate sulphate （PFSS） and polyferric sulphate （PFS）, were used in Yellow River water treatment. The influence of pH on coagulation effect was investigated under the optimum dosage, and the results show that both coagulants gave excellent organism removal efficiency when pH was 5.50. According to the variation of zeta potential in coagulation process, coagulation mechanisms of the coagulants were analyzed. An on-line laser scatter instrument was used to record the development of floc sizes during the coagulation period. For PFSS, pH exerted great influence on floc growth rates but little influence on formed floc sizes. In PFS coagulation process, when pH was 4.00, PFS flocs did not reach the steady-state during the whole coagulation period, while little difference was observed in floc formation when pH was 5.50 and above. The preformed flocs were exposed to strong shear force, and the variation of floc sizes was determined to evaluate the influence of pH on floc strength and re-growth capability. In comparison of the two coagulants, PFS flocs had higher floc strength and better recovery capability when pH was 4.00, while PFSS flocs had higher floc strength but weaker recovery capability when pH was 5.50 and above.

关 键 词：絮凝性能 pH值 混凝剂 水处理 铁基 黄河 行为 凝血 

分 类 号：X52[环境科学与工程—环境工程]