Sewage sludge addition to food waste synergistically enhances hydrogen fermentation performance

The effect of sewage sludge (SWS) addition on the H-2 fermentation of food waste (rev) was investigated. It was found that a slight addition of SWS (10:1 = FW:SWS on a COD basis) significantly enhanced the H2 fermentation performance, not only increasing the total amount of H-2 produced but accelerating the whole reaction, shortening the lag period, and increasing the H-2 production rate. Substrate degradation and microbial germination were also facilitated by SWS addition. A simple calculation reveals that the increased amount of H-2 production derived mostly from FW, indicating that SWS addition synergistically enhanced H-2 fermentation performance. This was attributed to the existence of Fe and Ca at much higher concentrations in the SWS compared to the FW. The batch process treating a mixture of FW and SWS was repeated and showed an average H-2 yield of 2.11 +/- 0.20 mol H-2/mol hexose(added), which was 13% higher than that of FW treated alone. (C) 2011 Elsevier Ltd. All rights reserved.