Comparison of two anaerobic systems for hydrogen production from the organic fraction of municipal solid waste and synthetic wastewater

Two laboratory scale anaerobic digestion systems for hydrogen production from organic fraction of municipal solid waste (OFMSW) and synthetic wastewater were compared in this study. One of them was formed by a coupled packed bed reactor (PBR) containing 19.4 L of OFMSW and the other an upflow anaerobic sludge bed (UASB) of 3.85 L. The reactors were inoculated with a mixture of non-anaerobic inocula. In the UASB the percentage of hydrogen yield reached 51% v/v and 127 N mL H-2/gvs removed with a hydraulic retention time (HRT) of 24 h. The concentration of synthetic wastewater in the affluent was 7g COD/L. For the PBR the percentage yield was 47% v/v and 99 N mL H-2/gvs removed with a mass retention time (MRT) of 50 days and the organic load rate of 16 gvs (Grams Volatile Solids)/(kg-day). The UASB and PBR systems presented maximum hydrogen yields of 30% and 23%, respectively, which correspond to 4 mol H-2/mol glucose. These values are similar to those reported in the literature for the hydrogen yield (37%) in mesophilic range. The acetic and butyric acids were present in the effluent as by-products in watery phase. In this work we used non-anaerobic inocula made up of microorganism consortium unlike other works where pure inocula or that from anaerobic sludge was used. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.