BioH2 production from food waste by anaerobic membrane bioreactor

Abstract

In this study, long term continuous bioH2 and volatile fatty acids (VFA) production potential in anaerobic membrane bioreactors (anMBR) from food waste by dark fermentation is investigated. Experiments of total 868 days are divided into 8 periods, each reflecting different operating conditions such as organic loading rates (OLR), hydraulic retention times (HRT) and pH regimes. Taking advantage of membrane technology, reactors are operated at solids content high as 50 g L_1 and reached to average 147 mL H2/g VS added production potential. The most effective H2 production, coupled with highest hydrolysis and acidification efficiency is achieved with pH = 7, 5 days of HRT and 18 kg COD m−3 d−1 of organic loading rate. It is also observed that in the periods which highest bioH2 production was achieved, were also the periods with highest B/A ratios. Microbial community was dominated by butryic acid producers according to Denaturing Gradient Gel Electrophoresis (DGGE) and clonning analysis and it is concluded that butyric acid pathway is the dominant bioH2 production mechanism in this study. With the membrane-supported completeley stirred tank reactor system, suitable conditions are not only provided for high bioH2 production, but also for the production of solids free permeate with volatile fatty acids content high as 29,765 mg L−1. Thus, with the innovative system proposed in this study, it is possible to establish a plant model suitable for the biorefinery concept.