Membrane fouling and removal performance of submerged aerobic membrane bioreactors: a comparative study of optimizing operational conditions and membrane modification

Abstract

BACKGROUND The effects of sludge retention time, organic loading rate, specific aeration demand per membrane area (SADm) and exploiting poly(vinyl chloride)/polycarbonate/modified silver nanoparticles (PVC/PC/MAg) nanocomposite membrane in membrane fouling and removal performance of submerged membrane bioreactors (SMBRs) were compared. A reference membrane bioreactor (R‐SMBR) having a pure PVC/PC hollow fiber membrane module and no operational condition improvement was used as a reference for comparison. RESULTS The results revealed that all of the parameters had a considerable influence on improving membrane fouling, among which optimizing SADm and installing nanocomposite membranes in the SMBRs had comparable performances. Although the nanocomposite membrane had excellent potential to boost the membrane flux up to 62% in comparison with the R‐SMBR, it did not play any noticeable roles in rectifying the removal efficiency of the SMBR. On the other hand, not only did SADm increase the membrane flux up to 55%, but it also increased about 5% of COD and 3% of NH4+‐N removal. CONCLUSIONS Sludge characteristics were not affected by membrane modification since the concentration of extracellular polymeric substances, soluble microbial products and mean particle size were 110 ± 1 mg g−1 VSS, 54 ± 1 mg L−1 and 50 μm, respectively, for both the R‐SMBR and the SMBR in which the modified membrane was installed. However, the operational parameters could also modify the treatment performance of the SMBRs by positively impacting on sludge characteristics besides mitigating membrane fouling. © 2021 Society of Chemical Industry (SCI).

Effect of organic loading rates on the performance of membrane bioreactor for wastewater treatment behaviours, fouling, and economic cost

“…Further, the optical and SEMmicrographs displayed the discrepancy between the three operating systems. While OLR values of 0.86 and 1.8 kg COD/m 3 d display a moist mount of big, compact, solid, well-settling flocs, the OLR 3.7 kg COD/m 3 d system shows open flocs and loose flocs with inter-floc filament bridging. Accordingly, the disappearance of filamentous bacteria when MBR was run at OLR 0.86 and 1.8 kg COD/m 3 d provided more evident proof of the cause of the performance disparity between the three operating systems.…”

“…Using biological wastewater treatment methods, including the conventional activated sludge (CAS) method, the majority of those challenges can be handled. Regardless, these processes are characterized by low selectivity for plenty of contaminants, like microbes and some organic contaminants 3 , 4 . Many problems with CAS can be resolved using the membrane bioreactor (MBR), an alternate treatment approach with a smaller footprint, higher quality effluent, and less sludge generation.…”

Optimizing dose of coagulant and pH values for membrane fouling control in a submerged membrane bioreactor

“…The activated sludge and wastewater from Daana Pharmaceutical Company (located in Tabriz, Iran), with a COD of 1000 ± 100 mg L −1 , NH 4 + ‐N of 45 ± 5 mg L −1 , and PO 4 −3 ‐P of 20 ± 3 mg L −1 , were utilized in all the stages. According to the optimum operational conditions described in our previous study for this activated sludge, 28 the same operating conditions — sludge retention time (SRT) = 20 days, organic loading rate (OLR) = 0.15 gCOD L −1 day −1 , mixed liquor suspended Solids (MLSS) = 8 g L −1 , aeration rate = 2 ± 05 L min −1 — were applied to the activated sludge to reach the steady‐state condition. The first stage of the study was carried out to find the highest possible concentration of PAC that could be added to the MBR without having any adverse effects on the removal performance of the activated sludge.…”

“…Thus, changing the sludge characteristics of MBR systems by novel operational methods has drawn enormous attention in recent years. 10 As a practical and economical technique, adding coagulants into MBRs has been widely used because they can both control membrane fouling and improve removal efficiency. 11,12 In general terms, membrane fouling in MBRs falls into three main categories: inorganic, organic, and biological fouling.…”

“…Indeed, optimizing operational conditions positively alters not only the membrane fouling but also the removal performances of MBRs, whereas membrane modification processes only improve membrane fouling in MBRs. Thus, changing the sludge characteristics of MBR systems by novel operational methods has drawn enormous attention in recent years 10 . As a practical and economical technique, adding coagulants into MBRs has been widely used because they can both control membrane fouling and improve removal efficiency 11,12 …”