Optimization of short chain volatile fatty acids production from household food waste for biorefinery applications

Household Food Wastes (HFW) are the most abundant organic wastes at urban level with a worldwide annual production of about 2 billion tons. This material can be the right feedstock for a carboxylate biorefinery platform. This work investigated the influence of different operational parameters (pH, temperature, Organic Loading Rate) on the Volatile Fatty Acids production and on their composition. It was demonstrated that, keeping constant the fermentation duration at 6 days, neutral pH, thermophilic temperature (55 °C) and an organic loading rate of 11 gTVS per Liter per day maximized the VFA production with a yield of 0.38 gVFA per gTVS fed. Under these conditions, the main VFAs were butyric and caproic acids with percentages around 60 and 20%, respectively.3. The analysis of the mixed microbial community performed over the reactor operation showed the dominance of members of Firmicutes phylum mainly affiliated to Clostridium and Lactobacillus genera. The process was mostly driven by Clostridium species in mesophilic runs characterized by stable VFAs production and highest yields whereas Lactobacillus was enriched under thermophilic operating conditions.