Material flow analysis of alternative biorefinery systems for managing Chinese food waste

Consistent material and substance flow diagrams for five alternative biorefinery scenarios for treating Chinese food waste were obtained by combining reported experimental research data and material flow analysis. The biorefinery alternatives produced biogas, biomethane, bioethanol and biodiesel in various combinations.

The compiled statistical data compiled showed that 100 t of Chinese food waste could produce 16 ± 1.1 t of biogas as a single technology and that other advanced biorefinery concepts could produce 5 ± 0.4 t of biomethane, 4 ± 1.6 t of bioethanol and/or 3 ± 0.2 t of biodiesel. In terms of substance flow, biorefinery scenarios transfer up to 75% of the total initial carbon in the food waste into bioproducts, while 22% of carbon is emitted, primarily as carbon dioxide.

The compost obtained by composting the dewatered digestate contained about 75% of input P, 27% of input K and 6% of input N. About 15% of input N was lost to the air during composting. The remaining C, N, P and K were in the wastewater. Introducing biorefinery concepts to the management of Chinese food waste can facilitate the generation of high-value bioproducts.

However, biorefinery concepts are technologically complicated and the energy consumption may triple relative to that of only biogas production. The issue of a considerably large liquid fraction in all cases still needs to be addressed. The material flow diagrams in this work constitute a consistent platform for assessing future scenarios for treating Chinese food waste from a technical, economical as well environmental perspective.