Assessing the removal of organic micropollutants by a novel baffled osmotic membrane bioreactor-microfiltration hybrid system

Abstract

A novel approach was employed to study removal of organic micropollutants (OMPs) in a baffled osmotic membrane bioreactor-microfiltration (OMBR-MF) hybrid system under oxicanoxic conditions. The performance of OMBR-MF system was examined employing three different draw solutes (DS), and three model OMPs. The highest forward osmosis (FO) membrane rejection was attained with atenolol (100%) due to its higher molar mass and positive charge. With inorganic DS caffeine (94-100%) revealed highest removal followed by atenolol (89-96%) and atrazine (16-40%) respectively. All three OMPs exhibited higher removal with organic DS as compared to inorganic DS. Significant anoxic removal was observed for atrazine under very different redox conditions with extended anoxic cycle time. This can be linked with possible development of different microbial consortia responsible for diverse enzymes secretion. Overall, the OMBR-MF process showed effective removal of total organic carbon (98%) and nutrients (phosphate 97% and total nitrogen 85%), respectively.

Removal of Organic Micro-Pollutants by Conventional Membrane Bioreactors and High-Retention Membrane Bioreactors

“…FO membrane is semipermeable and hence salt leakage is an unavoidable phenomenon that relates molecular weight of draw solution. OMBR operation at high sludge retention, coupling with MF/UF membrane could be an option to mitigate salinity build up [100]. Recently combining OMBR with electrodialysis (ED) was suggested [53].…”

“…This unique redox condition leads to entirely different microbial consortia capable to accomplish carbon and nitrogen biodegradation and stripping-off carbon (carbon dioxide (CO 2 )) and nitrogen (e.g., nitrogen (N 2 ) and nitrous oxide (N 2 O)) gases [3]. Pathak et al (2018) recently examined a novel baffled osmotic membrane bioreactormicrofiltration integrated process to study the removal of three OMPs employing inorganic and organic draw solutes. Model OMPs showed better removal with organic draw solutes and in general baffled OMBR showed very high total nitrogen (>85%) and excellent OMP removal.…”

“…Model OMPs showed better removal with organic draw solutes and in general baffled OMBR showed very high total nitrogen (>85%) and excellent OMP removal. Atrazine, a very refractory molecule and pesticide compound, had shown enhanced removal under unique redox environment under extended anoxic cycle time of 1.5 h that may have developed very different microbial community responsible for different enzyme secretion [100].…”

Nutrients Enrichment and Process Repercussions in Hybrid Microfiltration Osmotic Membrane Bioreactor: A Guideline for Forward Osmosis Development Based on Lab-Scale Experience

“…The OMBR facilitates the diffusion of pure water through a semipermeable FO membrane by virtue of the osmotic pressure difference between the sludge and draw solution (DS). The FO membrane as a robust alternative for the indirect and direct potable reuse of reclaimed wastewater can effectively retain organic micropollutants in the bioreactor, thereby enabling their subsequent biotransformation [9]. The FO system rejects most of the nutrients, such as PO 4 3− , NH 4 + , Ca 2+ , Mg 2+ , and enriches them in the bioreactor.…”

“…However, OMBR has some shortcomings, such as the salinity build-up in the sludge due to the reverse salt flux (RSF) from the DS and high retention capability of solutes by the FO membrane, resulting in decreased driving force for permeate flux, reduced microbial activity, and sludge deflocculation [12]. To eliminate the abovementioned problems, many studies have recently proposed the integration and parallel operation of a microfiltration (MF) or ultrafiltration (UF) modules to the OMBR system as an alternative strategy [7,9,10,13,14]. The hybrid microfiltration osmotic membrane bioreactor (MF-OMBR) system enables not only to bleed out salinity build-up from the bioreactor but also to subsequent direct recovery of concentrated nutrients (phosphorus and ammonia) from MF permeate easily by adjusting the pH [7,15].…”