A review of dark fermentative hydrogen production from biodegradable municipal waste fractions

In view of the implementation of a sustainable energy conversion framework, hydrogen is believed to potentially play a key role, significantly contributing to the reduction of the associated environmental impacts. Although H2 can be obtained from different sources through a variety of processes, positive environmental implications are specifically envisaged when H2 production is attained from renewable sources and low energy-demanding processes. H2 generation through dark fermentation of biodegradable organic residues has for such reasons deserved considerable attention over the last few decades. The main technical issue to be addressed is deemed to involve achieving efficient H2 generation at reasonably low costs at the same time gaining environmental credits. The great deal of scientific work on this issue as well as the large number of factors affecting fermentative hydrogen production claim for a harmonization and systematic comparison of results from different literature sources in order to derive reliable information about process yield and stability, and build related predictive models. To this aim, a review was conducted of studies on hydrogen production from kitchen waste (KW) and organic fractions of municipal solid waste (OFMSW) through dark fermentation, with more than 80 recent related publications being examined. The analysis focused on the effect of several factors, recognized as potentially affecting process evolution (including type of substrate and co-substrate and relative ratio, type of inoculum, food/microorganisms [F/M] ratio, applied pre-treatment, reactor configuration, temperature and pH), on the fermentation yield and kinetics. Experimental hydrogen production data from the reviewed literature were analyzed using statistical tools to derive information on the relative importance of the main variables of relevance also identifying existing mutual relationships