Environmental and economic evaluation of implementing membrane technologies and struvite crystallisation to recover nutrients from anaerobic digestion supernatant

The present study investigates the environmental and economic feasibility of implementing membrane technologies and struvite crystallisation (SC) for nutrient recovery from the anaerobic digestion supernatant. To this end, one scenario combining partial-nitritation/Anammox and SC was compared with three scenarios combining membrane technologies and SC. The combination of ultrafiltration, SC and liquid–liquid membrane contactor (LLMC) was the less environmentally impactful scenario. SC and LLMC were the most important environmental and economic contributors in those scenarios using membrane technologies. The economic evaluation illustrated that combining ultrafiltration, SC and LLMC (with or without reverse osmosis pre-concentration) featured the lowest net cost. The sensitivity analysis highlighted that the consumption of chemicals for nutrient recovery and the ammonium sulphate recovered had a large impact on environmental and economic balances. Overall, these results demonstrate that implementing membrane technologies and SC for nutrient recovery can improve the economic and environmental implications of future municipal wastewater treatment plants.This study has been supported by the Research Spanish Agency (AEI) through the Resources recycling from agri‐food urban and industrial wastes by integration of hybrid separation processes (W4V) project (PID2020-114401RB-C21) and the Catalan AGAUR Agency through the 2021-SGR-596. Additionally, the authors acknowledge the OpenInnovation – Research Translation and Applied Knowledge Exchange in Practice through University-Industry-Cooperation (OpenInnoTrain) with the grant agreement number (GAN)Peer ReviewedPostprint (author's final draft