Evaluation of hydrogen and volatile fatty acids production system from food waste

Food waste (FW) contains high amounts of organic substances and moisture like lipids, starches, and proteins. Dark fermentation (DF) has the ability to produce from FW high-value by-products, like lactic acid (LA), hydrogen (H2), alcohols (EtOH), short-chain fatty acids, and methane which produced in the oxidative stage of anaerobic digestion. Moreover, it has been proved that hydrogen is one of the promising energy sources which is vital for shrinking dependency on fossil fuels. Otherwise, volatile fatty acids (VFAs) have a wide-ranging of applications such as the utilization of an alternative carbon source. The comparison between the trial PHP (pretreatment, HRT, and pH) and the control system at the same hydraulic retention time (HRT) levels was studied. The paired-samples t-test showed that the trial system has a highly significant difference compared to the control system (P < 0.0001( for both H2 and VFAs production, where H2 production rate was 0.19 mL/L at the control system, and 263.82 mL/L at the trial system. On the other hand, the trial was 1.8 times higher than the control system for VFAs production. Based on the obtained results, the trial system is recommended for producing H2 and VFAs from waste food.