Effects of iron dust and HRT on the continuous biohydrogen production from food waste leachate using thermophilic ASBR

Abstract

Food waste leachate is not only tremendously generated in recycling plants and has but also high organic load. It is being at issue to bring about secondary environmental pollution and to increase the overall operation cost for treating it in recycling plants. Present treatments are hard to deal with food waste leachate so that advanced and economic techniques are urgently needed for treating and recycling for it. Hydrogen fermentation process generates hydrogen from carbohydrate obtained as refuse or waste products. As a sustainable energy source, hydrogen is a promising alternative to fossil fuels. It is a clean and environmentally benign fuel and has a high energy yield, which is about 2.75 times greater than that of hydrocarbon fuels. On that score, hydrogen production from food waste leachate could be a new alternative in the view of treatment and sustainable energy recovery. This study, therefore, performed to recover hydrogen from food waste leachate in continuous operation. First, the optimum conditions were evaluated to apply for continuous biohydrogen operation: feasibility, alkaline pretreatment, temperature, microorganism concentration, and iron dust effects. Five pH values, pH 9, 10, 11, 12, 13 and control were examined to find the optimum alkaline treatment condition for solubilization of food waste leachate. Impressive solubilization effects on food waste leachate were not detected. Twelve batch tests were performed to determine the optimum pre-treatment and temperature: alkaline pretreatment of pH 9, 10, 11, 12$, and 13, including control, in mesophilic and thermophilic operation respectively. The maximum specific hydrogen production rate was 2.67 mol $H_2/ mol hexose at control condition in thermophilic operation. To verify the feasibility of continuous hydrogen production, fed-batch experiment was conducted at control and pH 11 alkaline pretreatment in thermophilic operation. Averaged H2 yields were 2.76 mol $H_2/mol$ hexose at the control c...