Emergy Analysis and Life Cycle Assessment for Evaluating the Sustainability of Solar-Integrated Ecotechnologies in Winery Wastewater Treatment

Innovative approaches in sustainable wastewater management are vital in addressing climate change. This study introduces a novel assessment of solar-integrated ecotechnologies, focusing on the constructed wetland (CW) and microalgae-based systems, viz., high-rate algal pond (HRAP) and photobioreactor (PBR), for the treatment of winery wastewater. Utilizing Emergy analysis and life cycle assessment (LCA), we comprehensively compared these technologies in terms of environmental impact, resource recovery efficiency, and circular economy integration. Our Emergy analysis of the HRAP revealed a substantial reliance on renewable inputs (94%) and its lower nonrenewable resource consumption compared to the CW system. The Emergy sustainability index initially indicated a preference for the CW system (42.93 sej year(-1); sej = solar emjoule), but deeper analysis showed greater sustainability in the HRAP (341 sej year(-1)) and PBR (118 sej year(-1)). LCA results further revealed that PBR systems had a significant land-use footprint, impacting other environmental indices such as photochemical ozone formation and freshwater eutrophication. Additionally, the HRAP and PBR demonstrated a marked reduction in greenhouse gas emissions (-24800 and -23700 kg of CO2-eq, respectively) compared to the CW system (320 kg of CO2-eq). Life cycle cost analysis underscored the economic viability of these systems, with Scenario 3 (PBR) emerging as the most economically sustainable, exhibiting the highest internal rate of return (IRR) at 21.11% and a positive net present value after 20 years. Conversely, Scenario 1 (CW system), with its significant initial investment of AU$741220, showed no IRR due to the absence of revenue generation. Importantly, our study introduces circularity index scores as a novel element, revealing that the HRAP and PBR effectively incorporate circularity measures across various impact categories. These measures had moderate impacts, as indicated by scores close to but not exceeding 0.10, whereas the CW system showed no significant improvement, highlighting the need for more robust circularity strategies. Overall, our integrated framework provides a holistic view of the environmental impact and economic aspects, emphasizing the potential of solar-integrated microalgal systems in promoting circular (bio)economy practices and sustainable environmental management in the viticulture sector.