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Iranian Journal of Environmental Health, Science and Engineering
Iranian Association of Environmental Health (IAEH)
ISSN: p-ISSN: 1735-1979
Vol. 5, No. 4, 2008, pp. 225-234
Bioline Code: se08038
Full paper language: English
Document type: Research Article
Document available free of charge

Iranian Journal of Environmental Health, Science and Engineering, Vol. 5, No. 4, 2008, pp. 225-234

 en Effects Of 4-Chlorophenol Loadings On Acclimation Of Biomass With Optimized Fixed Time Sequencing Batch Reactor
Movahedyan, H.; Assadi, A. & Amin, M. M.

Abstract

Chlorinated phenols in many industrial effluents are usually difficult to be removed by conventional biological treatment processes. Performance of the aerobic sequencing batch reactor treating 4- chlorophenol containing wastewater at different loadings rates from 0.0075 to 1.2 g4CP/L.d was evaluated. The sequencing batch reactor was operated with fill, react, settle and decant phases in the order of 10:370:90:10 min, respectively, for a cycle time of 8 h at 10 days solid retention time and 16 h hydraulic retention time in the stable period. The effects of 4-chlorophenol loadings on the 4- chlorophenol and chemical oxygen demand removal percents, yield coefficient (Y), biomass variation and sludge volume index were investigated. High chemical oxygen demand removal efficiencies (95±3.5%) and approximately complete 4-chlorophenol removal (>99%) were observed even in the absence of growth substrate. The degradation of 4-chlorophenol led to formation of 5-chloro-2-hydroxymuconic semialdehyde, which was more oxidized, indicating complete disappearance of 4-chlorophenol via metacleavage pathway. A compact sludge with excellent settleability (sludge volume index=47±6.1 mL/g) developed during entire acclimation period. High removal efficiencies with sequencing batch reactor may be due to enforced short term unsteady state conditions coupled with periodic exposure of the microorganisms to defined process conditions which facilitate the required metabolic pathways for treating xenobiotics containing wastewater.

Keywords
Sequencing batch reactor, 4-chlorophenol, biodegradation, organic loading, mixed culture, xenobiotic

 
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