Several strategic approaches such as optimization of pretreatment methods of feedstocks, fermentation temperature and organic loading rates have been used to enhance
hydrogen fermentation of municipal and food wastes in the first stage of two-phase AD system [18,19,25]. Hydrogen yield in mesophilic dark fermentation is generally below 50 m3 H2 kg 1 VS. The present study compared the performance of one and two stage mesophilic fermentation of food waste based on biogas yield and production rate, and overall energy recovery. The research focused on the maximization of the overall energy production in the two phase system by opti- mizing food to microorganism (F/M) ratio in the first stage of hydrogen production while methane production in the second stage is relied on byproducts from acidogenic and acetogenic steps in the first stage.