Study on coagulation property of metal-polysilicate coagulants in low turbidity water treatment.
In order to remove the low turbidity present in surface water, a novel metal-polysilicate coagulant was used to treat the raw water taken from Tanjiang River in Guangdong Province. This study on the effects of Al/Fe molar ratio on the performance of a complex compound formed by polysilicic acid, aluminium and ferric salt (PAFS) showed that PAFS with Al/Fe ratio of 10:3 seemed to have the best coagulation performance in removing turbidity and color. Experimental results showed that under the conditions of polymerization time of 15 d, sedimentation time of 12 min, and pH of 6-8, PAFS with Al/Fe molar ratio of 10:3 had the best coagulation efficiency and lowest residual Al concentration. The turbidity decreased from 23.8 NTU to 3.23 NTU and the residual Al concentration was only 0.165 mg/L in the product water. It could be speculated that colloidal impurities and particulate Al were removed by adsorption bridging and electrical neutralization of long chain inorganic polymer coagulants.
Yang
Hai-yan
HY
School of Municipal & Environment Engineering, Harbin Institute of Technology, Harbin 150090, China. haiyanyang_hw@sina.com
Cui
Fu-yi
FY
Zhao
Qing-liang
QL
Ma
Chao
C
D000327:Adsorption; D000535:Aluminum / Q000032:analysis / Q000737:chemistry*; D002681:China; D003029:Coagulants / Q000737:chemistry*; D003116:Color; D005427:Flocculation; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000032:analysis / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*; D013997:Time Factors; D014867:Water / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D014881:Water Supply / Q000032:analysis / Q000592:standards
D003029:Coagulants; D011108:Polymers; D017640:Silicates; D014867:Water; D000535:Aluminum; D007501:Iron