title: Evaluation of reusing alum sludge for the coagulation of industrial wastewater containing mixed anionic surfactants.
abstract: A coagulation-flocculation process is typically employed to treat the industrial wastewater generated by the consumer products industry manufacturing detergents, soaps, and others. The expenditure of chemicals including coagulants and chemicals for pH adjustment is costly for treating this wastewater. The objective of this study was to evaluate the feasibility of reusing the aluminum sulfate (alum) sludge as a coagulant or as a coagulation aid so that the fresh alum dosage can be minimized or the removal efficiency can be enhanced. The experiments were conducted in a jar-test apparatus simulating the coagulation-flocculation process for simultaneous removals of organic matters, anionic surfactants, suspended solids, and turbidity. At the optimum initial pH value of 10 and the fresh alum concentration of 400 mg/L, the total suspended solids (TSS), total chemical oxygen demand (TCOD), total anionic surfactants, and turbidity removal efficiencies were 71.5%, 76.4%, 95.4%, and 98.2%, respectively. The addition of alum sludge as a coagulant alone without any fresh alum addition could significantly remove the turbidity, TCOD, and anionic surfactants. The TSS was left in the supernatants after the settling period, but would subsequently be removed by adding the fresh alum. The TSS, TCOD, and turbidity removal efficiencies were also enhanced when both the alum sludge and the fresh alum were employed. The TCOD removal efficiency over 80% has been accomplished, which has never fulfilled by using the fresh alum alone. It is concluded that the alum sludge could be reused for the treatment of industrial wastewater generated by the consumer products industry.
authors.affiliation: Environmental Science Program, Faculty of Science, Burapha University, Chonburi 20131, Thailand. jangkorn29@hotmail.com
authors.forename: Siriprapha
authors.initials: S
authors.lastname: Jangkorn
authors.forename: Sinchai
authors.initials: S
authors.lastname: Kuhakaew
authors.forename: Suwapee
authors.initials: S
authors.lastname: Theantanoo
authors.forename: Harit
authors.initials: H
authors.lastname: Klinla-or
authors.forename: Tongchai
authors.initials: T
authors.lastname: Sriwiriyarat
mesh_terms: D000534:Alum Compounds / Q000737:chemistry*; D000838:Anions; D057919:Biological Oxygen Demand Analysis; D005427:Flocculation; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000032:analysis*; D009391:Nephelometry and Turbidimetry; D059027:Recycling; D012722:Sewage / Q000737:chemistry*; D013501:Surface-Active Agents / Q000302:isolation & purification*; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000302:isolation & purification
chemical_list: D000534:Alum Compounds; D000838:Anions; D007220:Industrial Waste; D012722:Sewage; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical