Recovering dissolved methane using a hollow fiber membrane contactor (HFMC) A significant fraction of methane produced in AnMBRs generally remains dissolved in the liquid effluent, with reported values of 30-50% for AnMBR systems treating municipal wastewaters. For the NEWgenerator, if dissolved methane is released as a fugitive emission it represents roughly 18.6 kg CO2eq•cap -1 •yr -1 (33%) of the total photovoltaic configuration GHG emissions (Figure ). To reduce the dissolved methane leaving the system, a scenario involving the installation of a post-AnMBR HFMC was simulated. The micro-porous HFMC was selected for high liquid-gas separation (dissolved gas will diffuse through the membrane pores) and potential to maintain high fluxes and observe limited scaling. For this scenario, the HFMC was assumed to remove 63.3-98.9% (uniform uncertainty range) of dissolved methane based on process boundary conditions for separation which has been demonstrated for surrogate and real anaerobic effluents. The recovered dissolved methane was mixed with recovered biogas for sludge pasteurization. The addition of a HFMC comes at a tradeoff; a 14.3 kg CO2eq•cap -1 •yr -1 reduction in GHG emissions to a new system impact of 41.9 [27.2 -63.0] kg CO2-eq•cap -1 •yr -1 is achieved at the expense of 0.013 USD•cap -1 •d -1 increase to 0.157 [0.125 -0.205] USD•cap -1 •d -1 (a GHG mitigation cost of roughly 319 USD•Mg -1 of CO2) (Figures and).