title: Recycle of Alum recovered from water treatment sludge in chemically enhanced primary treatment.
abstract: An investigation was made to study the feasibility of recovering the Alum from coagulation sludges and reusing it in chemically enhanced primary treatment (CEPT) process to make the CEPT more cost-effective and recover the resource (Alum) efficiently. The optimum condition and efficiency of the acidification method for Alum recovery from coagulation sludge were investigated in the test. The results show that when the recovery rate of Alum reaches its highest level, 84.5%, the reduction rate of sludge is 35.5%. It turns out that the capability of recovered coagulant to remove turbidity, UV(254) and COD are 96%, 46% and 53%, respectively. The results prove that the recovered coagulants could be used in CEPT and the efficiency of recovered coagulant to remove pollutants is similar to that of fresh coagulant. Although some substances will be enriched during recycle, they have little effect on the quality of treated wastewater. The experiments verify that it would be an advisable and cost-effective way to recover Alum from coagulation sludges in water treatment and chemical wastewater treatment, and it could be then recycled to CEPT as well as reduce sludge volume.
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, P.O. Box 2602, 202 Haihe Road, Nangang District, Harbin, Heilongjiang Province, Postal code 150090, China. xgr@hit.edu.cn
authors.forename: G R
authors.initials: GR
authors.lastname: Xu
authors.forename: Z C
authors.initials: ZC
authors.lastname: Yan
authors.forename: Y C
authors.initials: YC
authors.lastname: Wang
authors.forename: N
authors.initials: N
authors.lastname: Wang
mesh_terms: D000534:Alum Compounds / Q000737:chemistry*; D002623:Chemistry Techniques, Analytical / Q000379:methods; D003029:Coagulants / Q000737:chemistry; D003124:Colorimetry; D003362:Cost-Benefit Analysis; D006863:Hydrogen-Ion Concentration; D019216:Metals, Heavy / Q000737:chemistry; D009391:Nephelometry and Turbidimetry; D012722:Sewage; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D014873:Water Pollutants / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D000534:Alum Compounds; D003029:Coagulants; D019216:Metals, Heavy; D012722:Sewage; D014873:Water Pollutants; C041524:aluminum sulfate