Economic and environmental feasibility assessment of two different AnMBR-based treatment schemes treating sulfate-rich urban wastewater

Two different facilities with AnMBR technology for sulfate-rich wastewater are analyzed. Scenario 1 consists of an AnMBR fed with raw wastewater. Scenario 2 couples AnMBR, primary settling and anaerobic digestion. Scenarios 1 and 2 were simulated with DESASS 7.1 software considering experimental data obtained from an AnMBR demonstration plant located in Carraixet facility (Valencia, Spain). Comparison between both scenarios is made based on their energy balances and applying the life cycle costing and life cycle assessment methodologies. Energy results showed net energy consumption of 0.148 kWh·m −3 in scenario 1 and a net energy savings of 0.057 kWh·m −3 in scenario 2 due to reduced mixing requirement and improved energy recovery. Energy savings also allows reducing operating expenditure in scenario 2 (€0.022 m −3 ) compared to scenario 1 (€0.066 m −3 ). Degassing membranes in scenario 1 (€0.020 m −3 ) also contribute to increase its capital expenditure (€0.083 m −3 ) over scenario 2 (€0.055 m −3 ). Scenario 2 shows a better environmental performance in all the categories evaluated. The absence of dissolved methane in the effluent and the improved energy recovery allowed scenario 2 to act as carbon sink (-0.033 kgCO 2eq ·m −3 ). Therefore, coupling AnMBR, primary settling and anaerobic digestion improves the feasibility of sulfate-rich wastewater treatments compared to AnMBR alone. • Performance of 2 AnMBR-based wastewater treatment facilities was evaluated. • Primary settler+AnMBR+anaerobic digestion shows better performance over AnMBR layout. • Primary settler+AnMBR+anaerobic digestion allows energy production of 0.057 kWh·m −3 . • Total annualized treatment cost of €0.077 m −3 was calculated. • Environmental assessment showed enhanced environmental performance.