title: Improvement of DOC removal by multi-stage AOP-biological treatment.
abstract: The single and multi-stages advanced oxidation process (AOP)-biological treatments were evaluated to apply for drinking water treatment, especially for the water containing less susceptible dissolved organic carbon (DOC) to ozone, comparing with the ozonation-biological treatment. Minaga reservoir water and the secondary effluent from a Municipal wastewater treatment plant were used as dissolved organic matter (DOM) solutions. DOC removals after 60 min AOP-biological treatment were 62% and 41% in the Minaga reservoir water and the secondary effluent, respectively, whereas those in the ozonation-biological treatment only 40% and 15% of DOC were removed, respectively. The result indicated that the single-stage AOP-biological treatment could improve DOC removal in comparison with the single-stage ozonation-biological treatment. This is because the AOP mineralized both biodegradable dissolved organic carbon (BDOC) produced in the early stage of oxidation and non-biodegradable dissolved organic carbon (NBDOC), whereas only BDOC was mineralized by further ozonation and NBDOC was not oxidized in the ozonation-biological treatment. The multi-stage treatment could not improve DOC removal in comparison with the single-stage treatment in the ozonation-biological treatment for the secondary effluent containing less susceptible DOC to ozone. However, the multi-stage AOP-biological treatment significantly reduced DOC and achieved 71% of DOC removal by 4 times repetition of 15 min oxidation, whereas DOC removal was 41% in the single-stage AOP-biological treatment for the same oxidation time. The improvement of DOC removal by the multi-stage AOP-biological treatment was due to BDOC removal as a radical scavenger by subsequent biological treatment in the early stage of oxidation and direct mineralization in the latter stage of oxidation.
authors.affiliation: Department of Material Science and Chemical System Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima, Hiroshima 739-8527, Japan. fahmi@environ.hiroshima-u.ac.jp
authors.lastname: Fahmi
authors.forename: Wataru
authors.initials: W
authors.lastname: Nishijima
authors.forename: Mitsumasa
authors.initials: M
authors.lastname: Okada
mesh_terms: D001673:Biodegradation, Environmental; D002244:Carbon / Q000737:chemistry*; D016166:Free Radical Scavengers; D009930:Organic Chemicals / Q000378:metabolism; D010083:Oxidants, Photochemical / Q000737:chemistry*; D010084:Oxidation-Reduction; D010126:Ozone / Q000737:chemistry*; D012995:Solubility; D018508:Water Purification / Q000379:methods*; D014881:Water Supply
chemical_list: D016166:Free Radical Scavengers; D009930:Organic Chemicals; D010083:Oxidants, Photochemical; D010126:Ozone; D002244:Carbon