Enhanced mesophilic bio-hydrogen production of raw rice straw and activated sewage sludge by co-digestion

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Abstract

In this study, batch biohydrogen production by co-digestion of raw rice straw and activated sewage sludge was investigated with different inoculum heat treatment, pH, S/X ratio (based on VS) and substrate sizes under mesophilic condition. In order to achieve a high bio-hydrogen yield and methanogens activity inhibition, heat treatment of inoculum was optimized at different exposure times (30, 45 & 60 min) and temperature ranges (80, 90 and 100 °C) prior to dark fermentation process. Collected data was analysed using response surface methodology (RSM). The heat treatment of inoculum at 100 °C for 60 min produced the highest bio-hydrogen yield of 14.22 NmL H2/g VS at concentration of 70.97% and Production of 0.073 NmL CH4/g VS at 0.17% concentration in total produced biogas. The raw rice straw was also co-digested with heat-treated inoculum at different ratios of volatile solids (2:1, 4:1 and 6:1) and initial pH (4, 4.75 and 5.5) as numerical variables and 4 categories of substrate size ((250–500 μm], (500 μm-2mm], (2–20 mm), [20–30 mm]). The highest bio-hydrogen yield of 14.70 NmL/g VS was recognized at the optimum initial pH of 5.01 and S/X ratio of 4.54:1 using 2–20 mm rice straw.

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Subject classification (UKÄ) – MANDATORY

  • Energy Engineering

Keywords

  • Bio-hydrogen, Co-digestion, Activated sewage sludge, Rice straw, Response surface methodology, S/X ratio
Original languageEnglish
Pages (from-to)16033–16044
Number of pages11
JournalInternational Journal of Hydrogen Energy
Volume40
Issue number46
Publication statusPublished - 2015
Publication categoryResearch
Peer-reviewedYes