Volatile fatty acids (VFAs) are a class of largely used compounds in the chemical industry, serving as starting molecules for bioenergy production and for the synthesis of a variety of products, such as biopolymers, reduced chemicals and derivatives. Because of the huge amounts of food waste generated from household and processing industry, 47 and 17 million tons per year respectively only in the EU-28 Countries, food wastes can be the right candidate for volatile fatty acids production. This review investigates all the major topics involved in the optimization of VFAs production from food wastes. Regarding the best operative conditions for the anaerobic fermenter controlled pH in the neutral range (6.0-7.0), short HRT (lower than 10 days), thermophilic temperatures and an organic loading rate of about 10 kgVS/md, allowed for an increase in the VFAs concentration between 10 and 25%. It was also found that additions of mineral acids, from 0.5 to 3.0%, and thermal pretreatment in the range 140-170 °C increase the organic matter solubilisation. Applications of VFAs considered in this study were biofuels and bioplastics production as well as nutrients removal in biological wastewater treatment processes.

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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 2 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.

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