Maximizing biohydrogen production from water hyacinth by coupling dark fermentation and electrohydrogenesis

Biohydrogen production via dark fermentation has shown immense potential for simultaneous energy generation and waste remediation. However, the low substrate conversion rates limit its practical feasibility. Therefore, the present work attempts to develop a single chamber microbial electrolysis cell (MEC) as an additional means for biohydrogen production. Different organic substrates including simple sugars and volatile fatty acids were demonstrated as potential substrates for H-2 production in MEC. The use of water hyacinth as sole substrate for H-2 production was examined. Furthermore, the feasibility of using MEC for second stage energy recovery after dark fermentation was explored. The two-stage process exhibited improved performance as compared to single stage MEC process with overall hydrogen yield of 67.69 L H-2/kg CODconsumed, COD removal of 70.33% and energy recovery of 46%. These results suggest that coupled dark fermentation-MEC process can be a promising means for obtaining high yield biohydrogen from water hyacinth. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.