Hydrolysis of polyaluminum chloride prior to coagulation:Effects on coagulation behavior and implications for improving coagulation performance  

作　　者：Zhongguo Zhang Jun Wang Dan Liu Jiuyi Li Xiaolin Wang Boyu Song Bing Yue Kehui Zhao Yun Song 

机构地区：[1]Key Laboratory of Energy-Water Conservation and Wastewater Resources Recovery(Environmental Protection Research Institute of Light Industry),China National Light Industry,Beijing 100089,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Beijing Key Laboratory of Industrial Wastewater Treatment and Resource Recovery,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China [4]Department of Civil and Environmental Engineering,Beijing Key Laboratory of Aqueous Typical Pollutants Control and Water Quality Safeguard,School of Civil Engineering,BeijingJiaotong University,Beijing 100044,China [5]Beijing Water Authority,Beijing 100038,China [6]Beijing Key Laboratory of Industrial Land Contamination and Remediation,Environmental Protection Research Institute of Light Industry,Beijing Academy of Science and Technology,Beijing 100089,China

出　　处：《Journal of Environmental Sciences》2017年第7期162-169,共8页环境科学学报（英文版）

基　　金：the Special Fund for the Technical Development of Scientific Research Institutions;financed by the Ministry of Science and Technology of the People's Republic of China(Nos.2011EG111307 and 2012EG111122);the Program for Overseas Talents of the Beijing Academy of Science and Technology(No.OTP-2013-015)

摘　　要：The effects of polyaluminum chloride（PACl） hydrolysis prior to coagulation on both the coagulation zone and coagulation performance of a kaolin suspension were investigated by a novel jar test named the ＂reversed coagulation test＂.The tests showed that PACl hydrolysis prior to coagulation decreased the performance of charge neutralization coagulation in the case of short-time slow mixing（10 min;G = 15 sec-1） and increased the optimal dosage for charge neutralization and sweep coagulation.Moreover,the hydrolysis time had insignificant effects on the size and zeta potential of PACl precipitates and the residual turbidity of the raw water.However,PACl hydrolysis prior to coagulation and the size of PACl precipitates had a negligible effect on the performance of sweep coagulation.The results imply that,in practice,preparing a PACl solution with deionized water,rather than tap water or the outlet water from a wastewater treatment unit,can significantly save PACl consumption and improve the performance of charge neutralization coagulation,while preparing the PACl solution with tap or outlet water would not affect the performance of sweep coagulation.In addition,the optimal rapid mixing intensity appears to be determined by a balance between the degree of coagulant hydrolysis before contacting the primary particles and the average size of flocs in the rapid mixing period.These results provide new insights into the role of PACl hydrolysis and will be useful for improving coagulation efficiency.The effects of polyaluminum chloride（PACl） hydrolysis prior to coagulation on both the coagulation zone and coagulation performance of a kaolin suspension were investigated by a novel jar test named the ＂reversed coagulation test＂.The tests showed that PACl hydrolysis prior to coagulation decreased the performance of charge neutralization coagulation in the case of short-time slow mixing（10 min;G = 15 sec-1） and increased the optimal dosage for charge neutralization and sweep coagulation.Moreover,the hydrolysis time had insignificant effects on the size and zeta potential of PACl precipitates and the residual turbidity of the raw water.However,PACl hydrolysis prior to coagulation and the size of PACl precipitates had a negligible effect on the performance of sweep coagulation.The results imply that,in practice,preparing a PACl solution with deionized water,rather than tap water or the outlet water from a wastewater treatment unit,can significantly save PACl consumption and improve the performance of charge neutralization coagulation,while preparing the PACl solution with tap or outlet water would not affect the performance of sweep coagulation.In addition,the optimal rapid mixing intensity appears to be determined by a balance between the degree of coagulant hydrolysis before contacting the primary particles and the average size of flocs in the rapid mixing period.These results provide new insights into the role of PACl hydrolysis and will be useful for improving coagulation efficiency.

关 键 词：Polyaluminum chloride（PACl） Precipitate Hydrolysis Charge neutralization Sweep coagulation 

分 类 号：X703[环境科学与工程—环境工程]