title: Impact of coagulation as a pre-treatment for UVC/H2O2-biological activated carbon treatment of a municipal wastewater reverse osmosis concentrate.
abstract: After coagulation of high salinity reverse osmosis concentrate (ROC) with either alum or ferric chloride followed by UVC/H2O2 treatment, biological activated carbon (BAC) was investigated for the removal of DOC. BAC treatment mainly removed low molecular weight (LMW) neutral molecules indicating that biodegradation was the predominant mechanism of organic matter removal. Coagulation with ferric chloride gave greater DOC reductions than alum both as a stand-alone treatment and after the sequence of UVC/H2O2 and BAC treatment. However, overall reduction after the sequence of coagulation, UVC/H2O2 and BAC treatment was only marginally greater for ferric chloride (68%) than for alum (62%). Trihalomethane formation potential and N-Nitrosodimethylamine concentration decreased markedly after UVC/H2O2 treatment. UVC/H2O2 treatment of the ROC led to the generation of extreme toxicity according to the Microtox assay, but no toxicity was observed after BAC, demonstrating its advantage for enabling safe disposal of the treated ROC. Implementation of coagulation as a pre-treatment and BAC as a post-treatment markedly reduced (6-8 times) the electrical energy dose (EED) required for the UVC/H2O2 process. The sequence of coagulation, UVC/H2O2 and BAC treatment was demonstrated as a potential process for the removal of organic matter from high salinity municipal ROC.
authors.affiliation: School of Civil, Environmental and Chemical Engineering, RMIT University, GPO Box 2476, Melbourne, 3001 Victoria, Australia.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Umar
authors.affiliation: School of Civil, Environmental and Chemical Engineering, RMIT University, GPO Box 2476, Melbourne, 3001 Victoria, Australia. Electronic address: felicity.roddick@rmit.edu.au.
authors.forename: Felicity
authors.initials: F
authors.lastname: Roddick
authors.affiliation: School of Civil, Environmental and Chemical Engineering, RMIT University, GPO Box 2476, Melbourne, 3001 Victoria, Australia.
authors.forename: Linhua
authors.initials: L
authors.lastname: Fan
mesh_terms: D002606:Charcoal; D002712:Chlorides / Q000737:chemistry; D004128:Dimethylnitrosamine; D005290:Ferric Compounds / Q000737:chemistry; D005374:Filtration; D006861:Hydrogen Peroxide / Q000737:chemistry*; D054712:Salinity; D022882:Trihalomethanes / Q000032:analysis; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D002606:Charcoal; D002712:Chlorides; D004128:Dimethylnitrosamine; D005290:Ferric Compounds; D006861:Hydrogen Peroxide; D022882:Trihalomethanes; D062065:Wastewater; D014874:Water Pollutants, Chemical; C024555:ferric chloride
keywords: Biological activated carbon; Coagulation; Disinfection by-products; Reverse osmosis concentrate; UVC/H(2)O(2)