Continuous treatment of azo acid dyes by photo-dependent denitrifying sludge

Article type: Research Article

Authors: Hong, Jing-lan | Otaki, Masahiro | Rouse, Joseph D. | Furukawa, Kenji

Affiliations: Department of Environmental Engineering of Ochanomizu University,2-1-1 Otsuka,Bunky-ku,Tokyo 112-8610,Japan, E-mail:g0170419@ edu.cc.ocha.ac.jp | Department of Civil and Environmental Engineering,Kumamoto University,2-39-1 Kurokami,Kumamoto 860-8555,Japan

Abstract: Simultaneous removals of dye and nitrate by photo-dependent denitrifying sludge(PDDS) have been demonstrated in a continuousflow bench-scale reactor.The best C/N for the degradation of azo dyes by PDDS was 1.5.The specific removal rate of azo dye AB92 decreased with a decrease in hydraulic retention time and increased with a decrease in solids retention time.The degradation rate of TOC decreased with a decrease in hydraulic retention time.AB92,which has nitro and hydroxyl substitutions in non-para positions,was uniquely degraded.During continuous flow treatment experiments using PDDS,complete degradation of azo dyes AB92 and AO20 at influent concentrations of 40 mg/L and 30 mg/L,respectively,was achieved with an HRT of 16.

Keywords: photo-dependent denitrifying sludge (PDDS), continuous treatment, simultaneous removals, azo dye, nitrate

Journal: Journal of Environmental Sciences, vol. 14, no. 3, pp. 296-302, 2002