A systematic review of waste and by-products olive oil treatment technologies and eco-efficiency assessment tools

The olive oil supply chain generates a notable amount of waste and by-products that, if not properly managed, can cause significant environmental impacts. On the other hand, they constitute a great source of high-added value compounds, although, the efficiency in the recovery of these compounds depends on the technologies used. For this reason, the present study provides a systematic literature review that analyses the state-of-the-art of waste and by-product treatment technologies in the olive oil supply chain, focusing on their valorisation strategies and evaluating their eco-efficiency. The systematic review was performed through the analysis of two queries: 1) focusing on the treatment technologies and valorisation pathway, and 2) focusing on the eco-efficiency evaluation, also including a circular economy and environmental sustainability perspective. The results are reported considering two macro-areas of interest: i) waste treatment and valorisation technologies; ii) identification of approaches and tools to evaluate their eco-efficiency with circular economy and environmental sustainability-oriented approaches. The findings identify: anaerobic digestion, membrane filtration, and composting as the main treatment technologies adopted; biogas production, polyphenols recovery, and agricultural reuse as the main valorisation pathway. The study of selected articles shows that the term eco-efficiency is rarely used, as well as the eco-efficiency indices. In addition, an integrated approach including circular economy and environmental sustainability together with eco-efficiency is not frequent. On the other hand, many articles focus on both the treatment efficiency and the environmental sustainability of these technologies. Thus, they may contribute to improving the eco-efficiency strategy and a zero-waste system.