Assessing biomass retention-driven enhancement of bioenergy and nutrient recovery potential in anaerobic membrane bioreactors for sustainable sewage sludge management

Sustainable management of sewage sludge (SewS) requires efficient strategies for energy recovery and nutrient reutilization. An anaerobic membrane bioreactor (AnMBR) and a continuous stirred tank reactor (CSTR) were operated to evaluate the advantages of membrane-integrated systems in SewS management. The AnMBR achieved a methane yield of 313.5 mL-CH4/g-VSadd, which was 11.3 % higher than that of the CSTR, attributed to the extended sludge retention time facilitated by membrane-induced biomass retention. The AnMBR also enhanced the potential for resource recovery by accumulating agricultural nutrients, with 817 g/t-SewS of NH4+-N and 395 g/t-SewS of TP retained in the permeate and filtrate-representing 40.4 % and 10.6 % increases compared to CSTR. The AnMBR-digested sludge saved 65.1 % flocculant for dewatering. With a higher exergy efficiency (11.8 % vs. 10.6 % for the CSTR), the AnMBR exhibited feasibility for resource recovery, suggesting its applicability for integrated SewS management.