Zheng H.et al., Production of bio-hydrogen using a membrane anaerobic reactor: limitations due to diffusion. Proceedings of the Environmental Research Event 2009, Noosa, QLD Production of bio-hydrogen using a membrane anaerobic reactor: limitations due to diffusion. Hang Zheng Division of Environmental Engineering, The University of Queensland, St. Lucia, QLD, Australia Email: h.zheng@uq.edu.au Cathryn O’Sullivan Division of Environmental Engineering, The University of Queensland, St. Lucia, QLD, Australia Email: c.osullivan1@uq.edu.au Ram Mereddy Division of Environmental Engineering, The University of Queensland, St. Lucia, QLD, Australia Raymond J. Zeng Advanced Water Management Centre, The University of Queensland, St. Lucia, QLD, Australia Email: r.zeng@awmc.uq.edu.au Mikel Duke Institute of Sustainability and Innovation, Victoria University, Melbourne, Australia Email: mikel.duke@vu.edu.au William Clarke Division of Environmental Engineering, The University of Queensland, St. Lucia, QLD, Australia Email: w.clarke@uq.edu.au Abstract: Hydrogen is a renewable pollution-free energy carrier, but its production is relying heavily on technologies such as coal gasification and steam reforming of non- renewable resources. Anaerobic digestion of organic wastes can produce hydrogen without non-renewable resources. In order to maximise the hydrogen yield during digestion, hydrogen must be removed at a substantial rate to avoid the accumulation to inhibitory level and the methane production. In this work, silica, alumina and hydrophobic polymeric microfiltration membranes were shown to work under submerged condition to remove hydrogen to the permeate gas phase. The different membranes trialled operated by different mechanisms, ranging from molecular scale diffusion (silica and alumina) to bulk flow (polymeric). The polymeric type was found to have the best hydrogen diffusion for the purpose of this work, while the alumina appeared to be completely blocked after 24 hours submerged in water. The hydrostable silica membrane was effective at also removing hydrogen, but permeance was too low to meet the production of the cells. Further investigations of the applicability and potential of membranes for this promising process are needed.