Producing volatile fatty acids and polyhydroxyalkanoates from foods by-products and waste: A review.

• Cheese whey, olive oil wastes and winery wastewaters are about 300 M tons worldwide. • About 85 kg of food wastes are annually produced by each people in the world. • VFA and PHA conversions can reach 0.9 gVFAs/gCOD and 0.7 gPHA/gVSS, respectively. • Wine wastes have the highest PHA yield (0.7 gPHA/gVSS), olive ones the lowest (0.3) • These yields allow to estimate the global annual PHAs production of about 260 M tons. Dairy products, extra virgin olive oil, red and white wines are excellent food products, appreciated all around the world. Their productions generate large amounts of by-products which urge for recycling and valorization. Moreover, another abundant waste stream produced in urban context is the Organic Fraction of Municipal Solid Wastes (OFMSW), whose global annual capita production is estimated at 85 kg. The recent environmental policies encourage their exploitation in a biorefinery loop to produce Volatile Fatty Acids (VFAs) and polyhydroxyalkanoates (PHAs). Typically, VFAs yields are high from cheese whey and OFMSW (0.55–0.90 g COD_VFAs /g COD), lower for Olive Mill and Winery Wastewaters. The VFAs conversion into PHAs can achieve values in the range 0.4–0.5 g PHA /g VSS for cheese whey and OFMSW, 0.6–0.7 g PHA /g VSS for winery wastewater, and 0.2–0.3 g PHA /g VSS for olive mill wastewaters. These conversion yields allowed to estimate a huge potential annual PHAs production of about 260 M tons. [ABSTRACT FROM AUTHOR]