Inhibitory effects of Cu (II) on fermentative methane production using bamboo wastewater as substrate

The toxic effects of Cu (II) present in bamboo industry wastewater (BIWW) upon its anaerobic biodegradability of organic content were investigated. The analysis through the Modified Gompertz model indicated that the optimum chemical oxygen demand (COD) concentration for digestion was 22,780 mg L-1 with a maximum R-m (maximum CH4 production rate) value of 2.8 mL h(-1), corresponding to a specific methanogenic activity (SMA) of 2.38 mLCH(4) gVSS(-1) h(-1). The inhibitory effects of Cu (II) on cumulative methane production depended on its concentration and contact time. Low concentrations (5 mg L-1) of Cu (II) showed a stimulating effect on methanogenesis. Methane was not detected when the Cu (II) concentration was increased beyond 300 mg L-1. The IC50 value of Cu (II), the Cu (II) concentration that causes a 50% reduction in the cumulative methane production, was 18.32 mg L-1 (15.9 mg Cu (II) gVSS(-1)). (C) 2011 Elsevier B.V. All rights reserved.