The effect of electrodialytic treatment and Na2H2EDTA addition on methanogenic activity of copper-amended anaerobic granular sludge: treatment costs and energy consumption

Abstract

The effect of electrodialytic treatment in terms of a current density, pH and Na2H2EDTA addition on the methanogenic activity of copper-amended anaerobic granular sludge taken from the UASB reactor from paper mill was evaluated. Moreover, the specific energy consumption and simplified operational and treatment costs were calculated. Addition of Na2H2EDTA (at pH 7.7) to copper-amended sludge resulted in the highest microbial activity (62 mg CH4-COD g VSS−1 day−1) suggesting that Na2H2EDTA decreased the toxic effects of copper on the methanogenic activity of the anaerobic granular sludge. The highest methane production (159 %) was also observed upon Na2H2EDTA addition and simultaneous electricity application (pH 7.7). The energy consumption during the treatment was 560, 840, 1400 and 1680 kW h m−3 at current densities of 0.23, 0.34, 0.57 and 0.69 mA cm−2, respectively. This corresponded to a treatment costs in terms of electricity expenditure from 39.2 to 117.6 € per cubic meter of sludge.