title: Comprehensive reuse of drinking water treatment residuals in coagulation and adsorption processes.
abstract: While drinking water treatment residuals (DWTRs) inevitably lead to serious problems due to their huge amount of generation and limitation of landfill sites, their unique properties of containing Al or Fe contents make it possible to reuse them as a beneficial material for coagulant recovery and adsorbent. Hence, in the present study, to comprehensively handle and recycle DWTRs, coagulant recovery from DWTRs and reuse of coagulant recovered residuals (CRs) were investigated. In the first step, coagulant recovery from DWTRs was conducted using response surface methodology (RSM) for statistical optimization of independent variables (pH, solid content, and reaction time) on response variable (Al recovery). As a result, a highly acceptable Al recovery of 97.5 ± 0.4% was recorded, which corresponds to 99.5% of the predicted Al recovery. Comparison study of recovered and commercial coagulant from textile wastewater treatment indicated that recovered coagulant has reasonable potential for use in wastewater treatment, in which the performance efficiencies were 68.5 ± 2.1% COD, 97.2 ± 1.9% turbidity, and 64.3 ± 1.0% color removals at 50 mg Al/L. Subsequently, in a similar manner, RSM was also applied to optimize coagulation conditions (Al dosage, initial pH, and reaction time) for the maximization of real cotton textile wastewater treatment in terms of COD, turbidity, and color removal. Overall performance revealed that the initial pH had a remarkable effect on the removal performance compared to the effects of other independent variables. This is mainly due to the transformation of metal species form with increasing or decreasing pH conditions. Finally, a feasibility test of CRs as adsorbent for phosphate adsorption from aqueous solution was conducted. Adsorption equilibrium of phosphate at different temperatures (10-30 °C) and initial levels of pH (3-11) indicated that the main mechanisms of phosphate adsorption onto CRs are endothermic and chemical precipitation; the surfaces are energetically heterogeneous for adsorbing phosphate.
authors.affiliation: Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul, 130-650, South Korea.
authors.forename: Kyung-Won
authors.initials: KW
authors.lastname: Jung
authors.affiliation: Future Environmental Research Center, Korea Institute of Toxicology, 17 Jeigok-gil, Munsan, Jinju, Gyeongsangnam-do, 660-844, South Korea.
authors.forename: Min-Jin
authors.initials: MJ
authors.lastname: Hwang
authors.affiliation: Department of Civil and Environmental Engineering, KAIST, 291, Daehak-ro, Yuseong-gu, Daejeon, 341-141, South Korea.
authors.forename: Dae-Seon
authors.initials: DS
authors.lastname: Park
authors.affiliation: Center for Water Resources Cycle Research, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul, 130-650, South Korea. Electronic address: khahn@kist.re.kr.
authors.forename: Kyu-Hong
authors.initials: KH
authors.lastname: Ahn
mesh_terms: D000327:Adsorption; D000535:Aluminum / Q000737:chemistry; D057919:Biological Oxygen Demand Analysis; D011232:Chemical Precipitation; D003116:Color; D060766:Drinking Water / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry; D059027:Recycling; D056910:Republic of Korea; D013783:Textile Industry; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D000535:Aluminum; D060766:Drinking Water; D010710:Phosphates; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Coagulant recovered residuals; Coagulant recovery; Drinking water treatment residuals; Response surface methodology; Textile wastewater