Evaluation of the environmental sustainability of biorefinery applied to cheese whey

Although the implementation of the waste biorefinery concept can open a wide array of possibilities to shift waste management towards recovery of high added value products, several barriers including technical, environmental, economic, logistic aspects need to be overcome (Alibardi et al., 2020). In particular, when considering environmental sustainability, the question is: do relatively complex processes producing high added-value materials provide better environmental performances with respect to well-established ones? With reference to a specific agro-industrial waste - cheese whey (CW), which is the main by-product of the dairy industry – innovative solutions for its management by biorefinery approach and conventional treatment are compared in this study. In particular, a three-stage polyhydroxyalkanoates (PHA) production process from CW, based on: i) preliminary dark fermentation (DF) producing H2-rich gas, ii) selection and enrichment of PHA-accumulating biomass in an aerobic sequencing batch reactor (SBR) operated under a feast-and-famine regime, iii) PHA accumulation in a batch reactor, is considered and compared with conventional anaerobic digestion (AD) of CW, assumed as a sort of benchmark in terms of environmental performances