**6. Conclusion(s)**

The biological production of VFAs from FW is one of the most promising sources for resource recovery due to the high availability of this waste. The production and recovery of VFAs from waste will accomplish one of the goals for this century, allowing to reduce the consumption of raw materials, as well as the waste accumulation/pollution and is in line with the circular economy approach by the substitution of the linear economic model of "take-make-consume-dispose" by the circular economy model. It has been demonstrated that VFAs have a great potential to be used for several applications, such as PHA and bioenergy production. Several process conditions (e.g. type of FW, pH, HRT, OLR, temperature, etc.) affects the VFA production in terms of VFA profile, concentration, and yield. Thus, these

*From Food Waste to Volatile Fatty Acids towards a Circular Economy DOI: http://dx.doi.org/10.5772/intechopen.96542*

factors must be taken into consideration when implementing this process to fit the final application. For instance, the acidogenic fermentation can be manipulated in order to produce different VFAs profiles, leading to PHAs with different compositions (taylor-made). At last, several pre-treatments can be applied to FW, enhancing the acidification process. However, positive and negative aspects must be considered when choosing the type of pre-treatment, namely costs and environmental concerns.
