| Summary: | 碩士 === 逢甲大學 === 化學工程學所 === 91 === Municipal sewage sludge was immobilized to produce hydrogen gas under anaerobic conditions. Cell immobilization was essentially achieved by gel entrapment approaches, which were physically or chemically modified by addition of silicon (SC), activated carbon (AC), sand, polyvinyl alcohol (PVA), and ethylene-vinyl acetate copolymer (EVA). Performance of hydrogen fermentation with a variety of immobilized-cell systems was assessed to identify the optimal type of immobilized cells for practical uses.
The optimized immobilized cells were examined for their hydrogen production activity with batch cultures under different temperatures and substrate concentrations. The results show that hydrogen fermentation was the most efficient at a temperature of 40℃ and a sucrose concentration of 20000 mg COD/L. The optimized immobilized cells were also utilized to produce hydrogen in continuous mode with fixed-bed bioreactors. The packed percentages tested were 10, 20, 35, and 50%. The result shows that 20% gave the best performance for hydrogen production with an average hydrogen generation rate of up to 2.2 L/h/L, which is comparable to that reported by other researchers worldwide using similar hydrogen-producing systems. It was found that a packed percentage of 20% induced formation of self-flocculated granular sludge to significantly enhance the hydrogen generation rate.
Like in batch tests, the hydrogen production rate was also optimal at a sucrose concentration of 20000 mg COD/L in fixed-bed operations. This suggests that the kinetics of hydrogen production was similar despite changes of operation mode with a larger scale. In addition, different carbon substrates were also used for fixed-bed processes, and sucrose appeared to be the most favorable substrate for hydrogen production, followed by fructose and glucose
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