Simultaneous nitrification-denitrification using baffled osmotic membrane bioreactor-microfiltration hybrid system at different oxic-anoxic conditions for wastewater treatment

Abstract

The efficacy of a baffled osmotic membrane bioreactor-microfiltration (OMBR-MF) hybrid system equipped with thin film forward osmosis membrane for wastewater treatment was evaluated at laboratory scale. The novel OMBR-MF hybrid system involved baffles, that separate oxic and anoxic zones in the aerobic reactor for simultaneous nitrification and denitrification (SND), and a bioreactor comprised of thin film composite-forward osmosis (TFC-FO) and polyether sulfone-microfiltration (PES-MF) membranes. The evaluation was conducted under four different oxic-anoxic cycle patterns. Changes in flux, salinity build-up, and microbial activity (e.g., extracellular polymeric substances (EPS) were assessed. Over the course of a 34 d test, the OMBR-MF hybrid system achieved high removal of total organic carbon (TOC) (86–92%), total nitrogen (TN) (63–76%), and PO4–P (57–63%). The oxic-anoxic cycle time of 0.5–1.5 h was identified to be the best operating condition. Incorporation of MF membrane effectively alleviated salinity build-up in the reactor, allowing stable system operation.