Preliminary environmental evaluation of cheese whey biorefinery

An integrated biorefinery process for cheese whey is proposed and evaluated. The cheese whey is fed to a first step of dark fermentation, to produce a biogas mainly composed by hydrogen and carbon dioxide. The biogas is processed by physical/chemical absorption, with the aim of producing an almost pure hydrogen stream for further use. The separated carbon dioxide is stored by the accelerated carbonation of industrial residues. The fermentate, exiting the dark fermentation, still rich in organic contents is fed to hydrothermal carbonization (HTC), producing hydrochar, to be used as biofuel or soil amendant. Basing on some already available laboratory test results, a preliminary environmental evaluation, by Life Cycle Assessment, was performed aimed at highlighting the main contributions of the biorefinery sub-process to the overall value of some selected environmental indicators. Results for Climate Change indicators show that biorefinery system provides negative impact; the main environmental credits come from CO2 storage and HTC process, while DF is the most critical process for the biorefinery supply chain.