•AnMBR can be used for recovering water, energy and nutrient from wastewater.•A pre-concentration step is necessary to facilitate resource recovery by AnMBR.•Key challenges include the buildup of ...salts & inhibitors, fouling, membrane stability.•Integrating AnMBR with complementary processes can address these challenges.
This review examines the potential of anaerobic membrane bioreactor (AnMBR) to serve as the core technology for simultaneous recovery of clean water, energy, and nutrient from wastewater. The potential is significant as AnMBR treatment can remove a board range of trace organic contaminants relevant to water reuse, convert organics in wastewater to biogas for subsequent energy production, and liberate nutrients to soluble forms (e.g. ammonia and phosphorus) for subsequent recovery for fertilizer production. Yet, there remain several significant challenges to the further development of AnMBR. These challenges evolve around the dilute nature of municipal wastewater, which entails the need for pre-concentrating wastewater prior to AnMBR, and hence, issues related to salinity build-up, accumulation of substances, membrane fouling, and membrane stability. Strategies to address these challenges are proposed and discussed. A road map for further research is also provided to guide future AnMBR development toward resource recovery.
In this study, a direct contact membrane distillation (MD) unit was integrated with an anaerobic membrane bioreactor (AnMBR) to simultaneously recover energy and produce high quality water for reuse ...from wastewater. Results show that AnMBR could produce 0.3–0.5L/g CODadded biogas with a stable methane content of approximately 65%. By integrating MD with AnMBR, bulk organic matter and phosphate were almost completely removed. The removal of the 26 selected trace organic contaminants by AnMBR was compound specific, but the MD process could complement AnMBR removal, leading to an overall efficiency from 76% to complete removal by the integrated system. The results also show that, due to complete retention, organic matter (such as humic-like and protein-like substances) and inorganic salts accumulated in the MD feed solution and therefore resulted in significant fouling of the MD unit. As a result, the water flux of the MD process decreased continuously. Nevertheless, membrane pore wetting was not observed throughout the operation.
Display omitted
•Stable biogas production and organic removal by AnMBR were observed.•MD complemented AnMBR treatment well to enhance contaminant removal.•AnMBR-MD achieved 76% to complete removal of all 26 TrOCs investigated here.•Foulants accumulated in MD feed and thus induced MD membrane fouling.
•Aquaporin FO membrane showed better transport properties than conventional membranes.•Aquaporin FO membrane resulted in less salinity build-up in OMBR operation.•Aquaporin FO membrane exhibited ...stable performance in OMBR operation.•Excellent contaminant removal by OMBR was achieved with the aquaporin membrane.
In this study, we investigated the performance of an osmotic membrane bioreactor (OMBR) enabled by a novel biomimetic aquaporin forward osmosis (FO) membrane. Membrane performance and removal of 30 trace organic contaminants (TrOCs) were examined. Results show that the aquaporin FO membrane had better transport properties in comparison with conventional cellulose triacetate and polyamide thin-film composite FO membranes. In particular, the aquaporin FO membrane exhibited much lower salt permeability and thus smaller reverse salt flux, resulting in a less severe salinity build-up in the bioreactor during OMBR operation. During OMBR operation, the aquaporin FO membrane well complemented biological treatment for stable and excellent contaminant removal. All 30 TrOCs selected here were removed by over 85% regardless of their diverse properties. Such high and stable contaminant removal over OMBR operation also indicates the stability and compatibility of the aquaporin FO membrane in combination with activated sludge treatment.
Deregulation of Pol III products causes a range of diseases, including neural diseases and cancers. However, the factors and mechanisms that modulate Pol III-directed transcription remain to be ...found, although massive advances have been achieved. Here, we show that STAT3 positively regulates the activities of Pol III-dependent transcription and cancer cell growth. RNA-seq analysis revealed that STAT3 inhibits the expression of TP73, a member of the p53 family. We found that TP73 is not only required for the regulation of Pol III-directed transcription mediated by STAT3 but also independently suppresses the synthesis of Pol III products. Mechanistically, TP73 can disrupt the assembly of TFIIIB subunits and inhibit their occupancies at Pol III target loci by interacting with TFIIIB subunit TBP. MiR-106a-5p can activate Pol III-directed transcription by targeting the TP73 mRNA 3' UTR to reduce TP 73 expression. We show that STAT3 activates the expression of miR-106a-5p by binding to the miRNA promoter, indicating that the miR-106a-5p links STAT3 with TP73 to regulate Pol III-directed transcription. Collectively, these findings indicate that STAT3 functions as a positive regulator in Pol III-directed transcription by controlling the miR-106a-5p/TP73 axis.
This study compared the removal of fifteen trace organic contaminants (TrOCs) by aerobic and anaerobic membrane bioreactors, denoted as AeMBR and AnMBR, respectively. Results show that the removal of ...TrOCs by either AeMBR or AnMBR was determined largely by their hydrophobicity. Almost all hydrophobic TrOCs were effectively removed (>60%) while the removal of hydrophilic compounds varied (3.6%–98.7%). AeMBR was more effective than AnMBR for the removal of all TrOCs investigated with a few exceptions. Compared to AeMBR, the removal of compounds containing nitrogen in their molecular structures (e.g. amitriptyline, carbamazepine, and atrazine) was higher by AnMBR. Of all TrOCs investigated, considerable accumulation in biosolids only occurred to amitriptyline, 4-tert-octyphenol and triclosan, particularly during AnMBR treatment. Nevertheless, biodegradation and/or biotransformation was the main mechanism for TrOC removal by both AeMBR and AnMBR. Moreover, removal of bulk organic matter indicated by total organic carbon and nitrogen was comparable for these two systems.
•Hydrophobic TrOCs could be effectively removed (>60%) by both AeMBR and AnMBR.•Removal of hydrophilic TrOCs by the two systems varied notably from 3.6% to 98.7%•AeMBR was more effective for the removal of most TrOCs than AnMBR.•AnMBR had higher removal of TrOCs with nitrogen in their molecular structures.•AeMBR and AnMBR were comparable for removal of organic matter (i.e. TOC and TN).
RNA polymerase III (Pol III) products play essential roles in ribosome assembly, protein synthesis, and cell survival. Deregulation of Pol-III-directed transcription is closely associated with ...tumorigenesis. However, the regulatory pathways or factors controlling Pol-III-directed transcription remain to be investigated. In this study, we identified a novel role of EGR1 in Pol-III-directed transcription. We found that Filamin A (FLNA) silencing stimulated EGR1 expression at both RNA and protein levels. EGR1 expression positively correlated with Pol III product levels and cell proliferation activity. Mechanistically, EGR1 downregulation dampened the occupancies of Pol III transcription machinery factors at the loci of Pol III target genes. Alteration of EGR1 expression did not affect the expression of p53, c-MYC, and Pol III general transcription factors. Instead, EGR1 activated RhoA expression and inhibited PTEN expression in several transformed cell lines. We found that PTEN silencing, rather than RhoA overexpression, could reverse the inhibition of Pol-III-dependent transcription and cell proliferation caused by EGR1 downregulation. EGR1 could positively regulate AKT phosphorylation levels and is required for the inhibition of Pol-III-directed transcription mediated by FLNA. The findings from this study indicate that EGR1 can promote Pol-III-directed transcription and cell proliferation by controlling the PTEN/AKT signalling pathway.
This study investigated the removal of antibiotics by sequencing-batch membrane bioreactor (SMBR) for swine wastewater treatment. Nine compounds categorized into three groups of commonly used ...veterinary antibiotics, namely sulfonamides, tetracyclines and fluoroquinolones, were evaluated. Results showed that both sulfonamides and tetracyclines were efficiently removed by SMBR (>90%) while a lower removal was observed for fluoroquinolones (<70%). Mass balance analysis evidenced that biodegradation/biotransformation was the main mechanism for the removal of antibiotics in SMBR operation. Moreover, sludge adsorption and membrane retention also slightly contributed to antibiotic removal. Of the three groups of antibiotics, tetracyclines and fluoroquinolones were more prone to accumulate in biosolids. It is noteworthy that antibiotics temporarily affected SMBR performance by inhibiting sludge growth and activity as well as increasing the concentrations of extracellular polymeric substances and soluble microbial products in the mixed liquor. Nevertheless, >60% of organic matter and nutrients in swine wastewater could be removed over SMBR operation.
Display omitted
•Antibiotics temporarily affected SMBR performance for swine wastewater treatment.•Sulfonamides and tetracyclines could be effectively removed (>90%) by SMBR.•A lower removal (<70%) by SMBR was observed for fluoroquinolones.•Tetracyclines and fluoroquinolones absorbed considerably onto sludge.•Antibiotic removal was still mainly driven by biodegradation/biotransformation.
•Process optimization and exogenous additives enhance micropollutant removal by MBRs.•High-retention membranes and AOPs complement MBR for effective micropollutant removal.•High-retention MBRs can ...also be developed to advance micropollutant removal.•Techno-economic evaluation of these strategies is needed for industrial MBR operation.
Membrane bioreactor (MBR) has been widely implemented to advance wastewater treatment and reuse. Nevertheless, conventional MBRs with porous microfiltration or ultrafiltration membranes are not designed for the removal of micropollutants, which ubiquitously occur in wastewater at trace concentrations, but potentially exert detrimental impacts to the ecosystem. Several effective strategies have been applied to improve MBR performance for micropollutant removal, particularly the hydrophilic and recalcitrant compounds. These strategies mainly include the optimization of operational conditions, employment of high-retention membranes to replace porous ones, addition of functional materials into bioreactor, and integration of effluent purification processes. In particular, effluent purification by advanced oxidation processes (AOPs) and high-retention membranes can complement MBR to secure almost complete removal of micropollutants. Nevertheless, further research is still necessary to evaluate the technical and economic feasibility of these strategies, especially for long-term treatment performance, to screen the suitable techniques for industrial MBR applications.
•Fundamentals and potential of OMBR to advance water reuse is reviewed.•Mechanisms of salinity build-up in OMBR are elucidated.•Impacts of salinity build-up on OMBR performance are ...delineated.•Proposed strategies to mitigate salinity build-up in OMBR are evaluated.•OMBR optimization and modification are emphasized for managing salinity build-up.
Osmotic membrane bioreactor (OMBR), which integrates forward osmosis (FO) with biological treatment, has been developed to advance wastewater treatment and reuse. OMBR is superior to conventional MBR, particularly in terms of higher effluent quality, lower membrane fouling propensity, and higher membrane fouling reversibility. Nevertheless, advancement and future deployment of OMBR are hindered by salinity build-up in the bioreactor (e.g., up to 50 mS/cm indicated by the mixed liquor conductivity), due to high salt rejection of the FO membrane and reverse diffusion of the draw solution. This review comprehensively elucidates the relative significance of these two mechanisms towards salinity build-up and its associated effects in OMBR operation. Recently proposed strategies to mitigate salinity build-up in OMBR are evaluated and compared to highlight their potential in practical applications. In addition, the complementarity of system optimization and modification to effectively manage salinity build-up are recommended for sustainable OMBR development.
PDF
