Insight into the effect of organic and inorganic draw solutes on the flux stability and sludge characteristics in the osmotic membrane bioreactor

Abstract

In this study, chloride based (CaCl and MgCl) and acetate based (NaOAc and MgOAc) salts in comparison with NaCl were investigated as draw solutions (DS) to evaluate their viability in the osmotic membrane bioreactor (OMBR). Membrane distillation was coupled with an OMBR setup to develop a hybrid OMBR-MD system, for the production of clean water and DS recovery. Results demonstrate that organic DS were able to mitigate the salinity buildup in the bioreactor as compared to inorganic salts. Prolonged filtration runs were observed with MgCl and MgOAc in contrast with other draw solutes at the same molar concentration. Significant membrane fouling was observed with NaOAc while rapid flux decline due to increased salinity build-up was witnessed with NaCl and CaCl. Improved characteristics of mixed liquor in terms of sludge filterability, particle size, and biomass growth along with the degradation of soluble microbial products (SMP) were found with organic DS.

Evaluating the effect of different draw solutes in a baffled osmotic membrane bioreactor-microfiltration using optical coherence tomography with real wastewater

“…Biomass characteristics play an important role in MBR operations, which governs the efficiency of the biological treatment as well as affects the membrane filtration processes (Lay et al, 2010;Siddique et al, 2017).…”

Treatment of high‐strength synthetic textile wastewater through anaerobic osmotic membrane bioreactor and effect of sludge characteristics on flux

“…Siddique et al. (2018) also described that buildup of salinity has an adverse effect on flocs stability and sludge flocculation. An increase in saline stress increases SMP and EPS production, which may depreciate the settlability and flocculation properties of MLSS (Zhang et al., 2014).…”

“…Mutlu et al (2019), in a recent study, described that due to salinity increase in MBR, disruption of floc structure was started, and fouling of membrane was accelerated. Siddique et al (2018) also described that buildup of salinity has an adverse effect on flocs stability and sludge flocculation. An increase in saline stress increases SMP and EPS production, which may depreciate the settlability and flocculation properties of MLSS (Zhang et al, 2014).…”

Integration of Forward Osmosis in Municipal Wastewater Treatment Applications

“…Osmotic Pressure DS with higher osmotic pressure than the feed generates higher J w Water Solubility Soluble compound produces higher osmotic concentration and therefore retains J w and water recovery at higher percentages To enhance the valorization of the resources contained in municipal wastewater, through the application of the anaerobic process several organic and ionic organic draw solutions have been investigated [13,14,74]. Bowden et al [14] compared 10 different ionic organic compounds as DS and slightly altered the selection methodology proposed by Achilli et al [15], introducing the parameter of biodegradability • 90% recovery of phosphorus using the MF system [12] • Accumulation of salts in the bioreactor is still a challenge [76] showed similar results with the application of synthetic wastewater, highlighting C 4 H 6 MgO 4 as suitable DS for OMBR applications, while sodium acetate (C 2 H 3 NaO 2 ) led to the development of dense membrane biofilm. Despite the many benefits of ionic organic solutions, it should be noted that their potential application is limited, as the re-concentration cost is high compared to inorganic solutions.…”