Volatile fatty acids production from household food waste

The present study aims at determining key factors and current constrains of household food waste (HFW) fermentation process and its large-scale implementation within the frame of biorefinery concept. The production of Volatile Fatty Acids (VFA) from HFW by a mixed microbial culture fermentation (MMC) was studied in both, batch and semi-continuous scale reactors. Results from batch scale trials without pH control pointed out that highest conversion yield obtained, 111 ± 20 mg of chemical oxygen demand, as VFA, per gram of volatile solids fed to the system, was reached after 6-7 days of fermentation. Moreover, during semi-continuous fermentation at uncontrolled pH and hydraulic retention time (HRT) of 6 d, was observed a VFA production of 3.3 ± 0.8 g·L^-1 on average, being increased up to a maximum of 30.1 g· L^-1 when pH was controlled at pH 5.5. In light of the results obtained, HFW should be considered a promising feedstock for the production of chemical intermediates like carboxylic acids and platform chemicals in general. Nevertheless, best optimal operational conditions have not been still properly deciphered and further research must be done to foster economic viability of VFA production in future urban biorefineries.