Natural inducement of biohydrogen from food waste by controlling operation temperature and its pH optimization

Abstract

The upcoming depletion of fossil fuels and the rising concerns about environmental pollution due to their tremendous use have attracted a lot of researches in developing alternative energy sources. Among them, hydrogen is recognized as a promising future energy carrier since it is environmentally clean, not emitting green house gases during combustion. $H_2$ is almost exclusively made by physico-chemical method that splitting fossil fuels, which is an environmental contradiction because a clean fuel is generated from polluting and limited sources. Thus, the interest in sustainable $H_2$ production ways including biological process has increased substantially. Among various biological ways, dark fermentation seems to be a promising method for its fast $H_2$ production rate, and environmentally friendly and economic aspect, especially when it is combined with waste treatment such as food waste and livestock waste. Previously, the innovative process named “$H_2$ fermentation of food waste without external inoculum” was studied at mesoophilic condition. However, it was restricted in mesophilic operation though it was generally accepted that thermophilic fermentation has higher performance than that of mesophilic. First, $H_2$ fermentation without adding external inoculums was performed at 55$^\circ C$ after pre-treated at various heating temperatures, 60~90$^\circ C$. The best performance was achieved using food waste without pretreatment indicating that $H_2$ could be naturally induced from food waste at thermophilic condition. Thus, effects of other operation parameters including operation temperature, initial and operation pH were studied in the next step. The $H_2$ production from food waste without external inoculum and pretreatment was investigated at different operation temperatures, 35~60$^\circ C$. Food waste was naturally decomposed and converted to $H_2$ when cultivated at 50-60$^\circ C$ in anaerobic state. At 50$^\circ C$, maximum $H_2$ yield was 1.5...