The Research On High Efficient Hydrogen Production From Corn Stalk Biomass By Integrating Dark Fermentation And Microbial Electrolysis Cell

Bio-H2production through dark-fermentation from various crop castoffs asfeedstock is considered to be a feasible method. However, the low conversionefficiency of substrate and the problem of effluent pollution are a serious challengethroughout the dark fermentation. The effluent from dark fermentation consistedchiefly of volatile fatty acids(VFAs) and alcohols. Microbial electrolysis cell(MEC)can convert the VFAs and alcohols into hydrogen gas. In this study, the enhanced H2production from corn stalk was carried out by combining dark fermentation andMEC.1. In the first stage of dark fermentation, the maximum hydrogen yield of129.8mL H2/g-corn stalk and hydrogen production rate of1.73m3/m3/d were observedunder the optimal conditions with Na2CO3dosage of800mg/l, Fe dosage of400mg/land substrate concentration of20g/l. The main metabolic by-products were acetate(HAc) and butyrate (HBu) in liquid phase, which was further used as feedstock ofMEC.2. In the second stage of MEC, we investigated the effects of fermentationeffluent concentration on H2generation and energy efficiency in MEC.The averageH2production rate of3.43±0.12m3/m3/d and energy efficiency of166±10%wererecorded under the optimal conditions with the effluent COD of4000mg/L and0.8Vapplied voltage. During MEC stage, about90±2%of acetate was converted to H2and the corresponding COD removal reached44±2%in MEC. The total H2yieldreached387.1mL H2/g-corn stalk by integrating dark fermentation and MECs.3. Furthermore, the microbial fuel cell（MFC）was started up using butyrate asalone substrate for improving the hydrogen production potential of butyrate in MEC.The effluent from hydrogen fermentation was used as substrates of MEC forhydrogen production.Both butyrate and effluent COD removal reached to39.3%and68%separately under0.5V applied voltage, the average H2production rate of2.41±0.12m3/m3/d and energy efficiency of215±11%were obtained with the effluent COD of9200mg/L. The overall H2yield was408.4mL H2/g-corn stalk by integrating darkfermentation and MEC.