A semi-industrial AnMBR plant for urban wastewater treatment at ambient temperature: Analysis of the filtration process, energy balance and quantification of GHG emissions

Abstract

A semi-industrial scale AnMBR urban wastewater treatment plant was operated for 580 days at ambient temperature (ranging from 10 to 30 ○C) to assess its long-term filtration performance, energy balance and GHG emissions. The applied 20ºC-standardized transmembrane flux (J20) was varied between 15 and 25 LMH and the specific gas demand per m2 of membrane (SGDm) was modified between 0.10 and 0.40 Nm3·m−2·h−1 (corresponding to a specific gas demand per permeate volume (SGDP) between 10 and 20 Nm3·m−3). The filtration strategy allowed successful long-term operations without any chemical cleaning requirements and little fouling for 233 days. The plant operated as a net energy producer for more than 50 % of the experimental period, with an average net energy demand of − 0.169 ± 0.341, − 0.190 ± 0.376 and − 0.205 ± 0.447 kWh·m−3, considering 0 %, 50 % and 70 % of dissolved methane recovery, respectively. Finally, demethanization of AnMBR effluent is needed to achieve an environmentally sustainable operation of the technology. Therefore, the combination of AnMBR with degassing membranes appears as a suitable alternative to conventional wastewater treatment.