초록
In the present work, alkali-treated sewage sludge (SS) was used as a seeding source for H<SUB>2</SUB> fermentation of food waste leachate (FWL). The role of alkaline treatment of SS was to suppress the activity of non-H<SUB>2</SUB>-producers in SS and also to enhance the solubility of SS. The effect of pretreatment pH and FWL:SS ratio on H<SUB>2</SUB> production was crucial, by changing the pH conditions and selecting the dominant species. High pretreatment pH and high SS content resulted in high initial pH conditions. The highest H<SUB>2</SUB> yield of 2.1 mol H<SUB>2</SUB>/mol hexose<SUB>added</SUB> was achieved at pretreatment pH 10 and a mixing ratio of FWL:SS = 3:5. At these conditions, the initial pH was 7.9, and cultivation pH was maintained within the reported optimum range of 5.5-6.5 during fermentation. It was found that pretreatment pH 9 was not strong enough to suppress the activity of non-H<SUB>2</SUB>-producers in SS, in particular, lactic acid bacteria (LAB). Microbial analysis results confirmed that LAB such as Lactobacillus sp. and Enterococcus sp. were the dominant species at pretreatment pH 9 while Clostridium sp., the main anaerobic H<SUB>2</SUB>-producers, were dominant at pretreatment pH 10.