A novel submerged anaerobic osmotic membrane bioreactor coupled to membrane distillation for water reclamation from municipal wastewater

A novel configuration of an osmotic anaerobic membrane bioreactor coupled with membrane-assisted distillation (OMBR-MD) in a single submerged module was proposed for domestic sewage treatment and potabilization. A steady permeate flux was achieved after the 22nd day of monitoring, in which the draw solution (DS) was diluted by the forward osmosis (FO) permeate at the same rate in which it was concentrated by the membrane distillation (MD). Salinity build-up inside the bioreactor contributed to fouling in the FO membrane since it increases the production of soluble microbial products and extracellular polymeric substances. In addition, organic matter accumulated in DS, due to the closed-loop system, may be the main cause for fouling in MD membranes at the latter stages. The OMBR-MD presented great removal for organic matter (91%), phosphorous (95%) and ammonium nitrogen (71%). Alkalinity accumulation within the bioreactor prevented a significant change in bulk solution pH (8.0 – 8.4), reducing the effects of volatile fatty acids production on methanogenic performance. The OMBR-MD removal efficiencies were higher than 96% for all 7 selected pharmaceutical drugs. Additionally, the MD distillate attained eight out of the nine parameters assessed for potable water standards established in Brazilian legislations and recommendations from US EPA, including Escherichia coli. Therefore, the novel OMBR-MD proved to be a feasible alternative for treating municipal wastewater, generating a high-quality distillate.