Effect of organic loading rates on the membrane performance of a thermophilic submerged anaerobic membrane bioreactor for primary sludge treatment from a pulp and paper mill. Issue 3 (June 2022)

• Record Type: Journal Article
• Authors: Bokhary, A.; Leitch, M.; Liao, B.Q.
• Is Part Of: Journal of environmental chemical engineering. Volume 10:Issue 3(2022)
• Publication Date: 2022-06
• Subjects: Membrane performance -- OLR -- Biogas yield -- Primary sludge -- Anaerobic digestion -- Membrane bioreactor; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2022.107523
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: The effect of organic loading rates (OLRs) on membrane performance and mixed-liquor suspended solids (MLSS) properties were examined using a laboratory-scale thermophilic submerged anaerobic membrane bioreactor (ThSAnMBR) that treats primary sludge from a thermomechanical pulp mill. Membrane performance was evaluated by monitoring its flux and corresponding transmembrane pressure (TMP). Changes in membrane chemical and physical properties resulting from operating conditions were investigated using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), contact angle, energy-dispersive X-ray analyzer (EDX), and pore size measurement. While MLSS properties are analyzed by X-ray photoelectron spectroscopy (XPS), zeta potential, and particle size distribution (PSD) analysis. Membrane performance and MLSS properties were studied at different OLRs ranging from 1.5 to 3.9 kg-TSS/m 3 d, and hydraulic retention times (HRTs) of 3–8 d. This study showed that the increased OLR reduced the membrane performance and degradation of the primary sludge, as well as the biogas yield. This result indicates that OLR of less than 1.5 kg TSS/m 3 d, HRT of 8d, and solids retention time (SRT) of 32d should be maintained to achieve stable membrane performance and better biogas production. Also, results showed that important changes occurred on the membrane morphology and MLSS characteristics under the tested operating conditions. High-resolution SEM images reveal distinct differences in the pore morphology between the virgin and used membranes indicating the effect induced by the operating conditions. Thermophilic temperature led to an expansion of membrane pores. Overall, the primary sludge from pulp and paper mills can be treated successfully by ThSAnMBR for methane production with stable membrane performance and high treatment efficiency. Graphical Abstract: ga1 Highlights: The effect of OLRs on membrane performance and MLSS properties was studied. Important changes occurred in the membrane morphology due to induced environment. Primary sludge from thermomechanical pulp mill can be successfully treated by AnMBR. Thermophilic temperature led to an increase of the portion of large membrane pores. A higher OLR or shorter HRT led to more irremovable membrane fouling.