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Water Science & Technology—WST Vol 57 No 8 pp 1155–1160 © IWA Publishing 2008 doi:10.2166/wst.2008.093

Treatment of low and medium strength sewage in a lab-scale gradual concentric chambers (GCC) reactor

L. Mendoza, M. Carballa, L. Zhang and W. Verstraete

Experimental Reproduction Centre (CEYSA), Agricultural Faculty, Technical University of Cotopaxi, Latacunga, Ecuador E-mail: lauramen_2000@yahoo.com
Laboratory of Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, B-9000, Ghent, Belgium E-mail: willy.verstraete@ugent.be; marta.carballa@ugent.be; lezhanghua@hotmail.com


ABSTRACT

One of the major challenges of anaerobic technology is its applicability for low strength wastewaters, such as sewage. The lab-scale design and performance of a novel Gradual Concentric Chambers (GCC) reactor treating low (165±24 mg COD/L) and medium strength (550 mg COD/L) domestic wastewaters were studied. Experimental data were collected to evaluate the influence of chemical oxygen demand (COD) concentrations in the influent and the hydraulic retention time (HRT) on the performance of the GCC reactor. Two reactors (R1 and R2), integrating anaerobic and aerobic processes, were studied at ambient (26°C) and mesophilic (35°C) temperature, respectively. The highest COD removal efficiency (94%) was obtained when treating medium strength wastewater at an organic loading rate (OLR) of 1.9 g COD/L·d (HRT = 4 h). The COD levels in the final effluent were around 36 mg/L. For the low strength domestic wastewater, a highest removal efficiency of 85% was observed, producing a final effluent with 22 mg COD/L. Changes in the nutrient concentration levels were followed for both reactors.

Keywords: anaerobic digestion; developing countries; reactor configuration, sewage, temperature


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