Hybrid life cycle assessment of agro-industrial wastewater valorisation.

Wastewater from food processing facilities can have high nutrient valorisation potential. Valorising sugar-rich agro-industrial wastewater may have significant impacts on sustainability of wastewater treatment plant (WWTP). The objective of this study is to evaluate the environmental, economic and social impacts of a novel wastewater valorisation technology. This technology is designed to produce single cell protein (SCP) from wastewater of a fruit juice processing facility. To evaluate the comprehensive sustainability impacts on WWTP and overall background economy, a hybrid life cycle assessment model was developed by combining the multi-regional input-output database (Exiobase) with process-based life cycle inventories of conventional and AgroCycle WWTP. The results indicated the upstream impacts of wastewater could have significant influence on sustainability of WWTP with nutrient valorisation. Therefore the 'zero burden assumption' should not be adopted for upstream wastewater. For the sustainability performance, valorising nutrients from WWTP with AgroCycle technology can improve the environmental performance of WWTP. However, the positive social-economic impacts were directly associated with WWTP system, not the whole background economy. The production of SCP could reduce the Gross Value Added (GVA) and employment in the 'oil seeds sector'. In order to improve the social-economic impacts and promote a circular bioeconomy model in the fruit juice sector, further development is required to improve valorisation productivity and create a better value chain for valorised products.