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关键词： Refinery wastewater   OMBR   Water reuse   Draw solution   Salinity build up   Effluent treatment  

摘要： The present work considered an osmotic membrane bioreactor (OMBR) for the treatment of a complex and recalcitrant refinery wastewater. Magnesium chloride (MgCl2) was employed as draw solution (DS) to minimize the effects of salinity build up within the mixed liquor (ML). The flux decrease was mainly attributed to the salinity build up. Due to the higher contaminant retention time compared to conventional membrane bioreactor or hybrids UF-OMBRs, the recalcitrant compounds started to be degraded. Moreover, the reverse flux of magnesium favored a higher granulation of the sludge, which in turn enhanced nitrification and denitrification processes. The increase in fouling resistance was attributed to deposits formation, as showed in SEM micrographs and EDX spectra, and the pore blockage by low molecular weight compounds originated by the biological degradation. The increase in salinity (maximum similar to 10 g/L) lead to a higher production of SMP and EPS protein like substances, which have lower effect in fouling propensity. Furthermore, even though the ML volatile suspended solids (MLVSS) and ML suspended solids (MLSS) decreased, the mean MLVSS/MLSS ratio was 0.75 +/- 0.15, which shows that the salinity build up did not degrade the biological activity. In this sense, when the OMBR is operated with MgCl2 as DS, the permeate shows good physical-chemical quality due to increased contaminants retention time, demonstrating that the system can be used even for applications that demands elevated physical-chemical quality.

关键词： FO-AnMBR   Industrial wastewater   Methane   Wastewater treatment   Shear stress   Water recovery  

摘要： Since most of the water used for brewing becomes wastewater, the reduction of wastewater streams is of great importance for the brewing industry. Anaerobic membrane bioreactors incorporating forward osmosis membranes (FO-AnMBRs) could provide an energy-efficient solution for the treatment of brewery wastewater, while recovering water and simultaneously producing biogas. The start-up period of two lab-scale FO-AnMBRs fed with real (R(rea)l) and synthetic (R-synth) brewery wastewater was assessed and compared to continuous stirred tank reactor operation without membranes. During reactor start-up, the hydraulic retention time (HRT) of the reactors was reduced from 20 to 2.5 days while increasing the organic loading rate. The CH4 production of R-synth and R-real increased up to nine-fold when the membranes were integrated, demonstrating the principle that FO-AnMBR can be used for brewery wastewater treatment. However, process stability decreased with decreasing HRT, possibly due to shear stress and the inadequate C/N ratio of the wastewater.

关键词： Membrane bioreactor   Membrane biofouling   Quorum quenching   Mobile porous balls   Media durability  

摘要： Microbial quorum quenching (QQ) has been recognized as an effective anti-biofouling strategy for membrane bioreactors (MBRs), but long-term hydrogel QQ media durability is uncertain. In this study, we propose a new media design to enhance anti-biofouling efficacy and mechanical media stability. Mobile porous hard-shell balls to hold QQ sheets (named QQ balls) were found to be superior in QQ stability to both fixed and freely moving QQ sheets. Fouling mitigation by QQ balls was significant even at the lowest aeration intensity tested (51 s(-1)), in contrast to other QQ media. QQ balls saved substantive energy (similar to 50%) at similar or lower fouling rates (2.8-3.2 kPa/d) compared to the others tested at the higher aeration intensity (72 s(-1)). QQ balls maintained their initial high level of QQ activity (similar to 3.0 h(-1)) during long-term use (greater than160 d), whereas other types of QQ media did not (< 1.3 h(-1)). The mechanical strength of free QQ media significantly deteriorated over time (similar to 87-100% losses after 160-d use), but QQ balls prevented the active media from such damage. QQ media had no impacts on treatment efficiencies. A QQ media structure comprising a hard porous shell and inner active media encapsulating QQ bacteria is a promising QQ media architecture for sustainable MBR applications.

关键词： Denitrifying woodchip reactor   DNRA   Nitrous oxide   Wastewater treatment  

摘要： High levels of nitrogen originating from blasting operations, for example at mining sites or quarries, risk contaminating water bodies through leaching from waste rock dumps. Woodchip bioreactors can be a simple and cost-effective way of reducing nitrate concentrations in the leachate. In this study we investigated how bottle sedge, barley straw, and pine woodchips used as electron donors for denitrification influenced microbial community composition and nitrate removal in lab-scale bioreactors during 270 days. The reactors were operated to ensure that nitrate was never limiting and to achieve similar nitrate removal (%). Distinct bacterial communities developed due to the different substrates, as determined by sequencing of the 16S rRNAgene. Sedge and straw reactors shared more taxa with each other than with woodchips and throughout the experimental period, sedge and straw were more diverse than woodchips. Cellulose degrading bacteria like Fibrobacteres and Verrucomicrobia were detected in the substrates after 100-150 days of operation. Nitrate removal rates were highest in the sedge and straw reactors. After initial fluctuations, these reactors removed 5.1-6.3 g N m(-3) water day(-1), which was 3.3-4.4 times more than in the woodchip reactors. This corresponded to 48%, 42%, and 44% nitrate removal for the sedge, straw, and woodchip reactors respectively. The functional communities were characterized by quantitative PCR and denitrification was the major nitrate removing process based on genetic potential and water chemistry, although sedge and straw developed a capacity for ammonification. Gene ratios suggested that denitrification was initially incomplete and terminating with nitrous oxide. An increase in abundances of nitrous oxide reducing capacity in all substrate types towards the end increased the potential for less emissions of the greenhouse gas nitrous oxide. (C) 2020 The Author(s). Published by Elsevier B.V.

关键词： Denitrification bioreactor   Non-point pollution   Subsurface drainage   Infrared bioaugmentation  

摘要： Woodchip bioreactors can effectively remove waterborne nitrates from subsurface agricultural drainage and prevent the eutrophication of receiving water, but rapid biofilm growth can severely reduce water flux and denitrification efficiency of this practice within a few years. Tourmaline minerals with thermal excitation could generate reactive oxygen species which would inhibit bacterial growth. In this study, laboratory scale woodchip bioreactors were set up to test the anti-clogging and denitrification efficiency of heated woodchips with tourmaline, heated woodchips without tourmaline, and unheated woodchips. The results showed that the heated tourmaline treatment could reduce the clogging and optimize the nitrate removal rate (47.6 g N/m(3)/day) under all three hydrologic retention times tested (1, 4, and 8 h). Dissolved oxygen and pH values fluctuated with the removal rate and temperature change, while temperature was identified as the key factor impacting the tourmaline treatment. The heated tourmaline treatment had the lowest biofilm growth (lowest DNA concentration), while the 16S rRNA and a higher abundance of nirS-, nirK-, and nosZ-encoding denitrifying bacteria (based on qPCR) confirmed the higher denitrification efficiency of the heated tourmaline treatment. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Air flow rate   Dissolved oxygen, nutrient removal   Hybrid membrane bioreactor   Sequencing batch reactor   Wastewater treatment  

摘要： This study addressed the impact of air flow rate on the performance, membrane fouling behaviour and microbial community of a sequencing batch conventional membrane bioreactor (SB-MBR) and a sequencing batch hybrid membrane bioreactor (SB-HMBR) with carrier media for biofilm growth. Two different scenarios were evaluated: high (6.4 L min(-1)) and low (1.6 L min(-1)) air flow rates, associated with high (4.5 mg L-1) and low(1.5 mg L-1) dissolved oxygen (DO) concentrations and specific aeration demand per membrane area (SAD(m)) of 0.426 and 0.106 m(3) m(-2) h(-1), respectively. Both reactors were subjected to alternating non-aerated and aerated conditions for organic matter (as chemical oxygen demand - COD), nitrogen and phosphate removal from a municipal wastewater. From the bacterial community analysis, the key players in nutrient removal processes were assessed. The results showed that COD removal efficiencies were above 95% in both MBRs, regardless of the aeration intensity, while complete ammonium removal was observed at the higher DO. However, nitrifying activity was adversely affected under low DO levels. High nitrification levels were re-established faster in the hybrid MBR, thanks to the presence of biofilm, where nitrifying activity was favoured and the bacterial community profile did not exhibit substantial changes upon DO reduction. A higher denitrification potential was found for the carrier-based MBR, resulting in lower effluent nitrate concentrations. Regarding phosphorus removal, a slight improvement was observed in the SB-HMBR at reduced DO, while in the SB-MBR it remained practically constant. Moreover, the specific phosphate uptake rate exhibited a significant increase, especially in the hybrid MBR, reaching 44.6 mgP gVSS(-1) h(-1). At lower aeration rate, however, worse filterability and higher membrane fouling rates were observed, especially in the conventional MBR. Overall, the results demonstrated that the hybrid MBR better withstood the reduced

关键词： Domestic wastewater characteristics   Green household sewage   Onsite septic systems   SludgeHammer   Simultaneous nitrification-denitrification (SND)   Enhanced biological phosphate removal (EBPR)  

摘要： This study aimed to investigate the efficacy of private septic systems retrofitted into aerobic bioreactors with 'SludgeHammer' technology. In addition, the study attempted to characterize the strength of domestic wastewater released from 'green' households practicing water conservation strategies. Ten retrofitted onsite septic systems were studied in the Edmonton area, Alberta (AB) Canada during winter. These systems could remove BOD5 and TSS by 92 +/- 5 and 92 +/- 6% respectively which, according to Albertan regulatory standards, were characteristic removal efficiencies of the secondary treatment in the subsequent drain field. These removal efficiencies were remarkable given the strength of the influent wastewater. The raw wastewater carried significantly high pollutant concentrations (1160 +/- 350 mg BOD5/L, 1653 +/- 1174 mg TSS/L, 99 +/- 19 mg NH4+-N/L, 100 +/- 56 mg TN/L, and 39 +/- 28 mg PO43--P/L), characterizing it as high-strength domestic wastewater. Mixing provided by the aerator could only suspend 1/34th (3% m/m) of the solids in the bioreactor and consequently released significantly low solid concentrations (195 +/- 206 mg TSS/L) into the final treatment component. As such, this technology did not impair the natural function of septic tanks or did not create any unintended excessive solid loading on drain field as a consequence of the added mixing energies provided by the active aeration. Nitrogen balance suggested the possibility of simultaneous nitrification and denitrification (SND) in the aerobic bioreactors. In some cases, PO43--P removal efficiency was as high as that in enhanced biological phosphate removal (EBPR) process (81-97%). Phosphorus balance estimated that non-assimilative pathways (i.e., EBPR + biologically induced phosphate precipitation (BIPP)) contributed 50-99% to overall phosphorus removal in the system. Long HRTs, high influent BOD5 and anaerobic/aerobic zoning in the bioreactor most likely provided favorable conditions for SND an

关键词： Fossil fuel   Renewable technology   Sustainable   Bioreactors   Cleaner fuel  

摘要： The utilization of fossil fuels causes adverse effects on the human and environment and the world is facing the depletion of these resources. The conventional technologies available for hydrogen production create greenhouse gases which cause a serious threat to the surroundings. Hence, there is a need to create a renewable and alternative technique for hydrogen production. The biological method acts as renewable technology to conventional technologies. For the present and future generations, the development of bioreactors may provide a sustainable route to meet cleaner hydrogen production. The conventional methods like reforming process, gasification process, thermochemical method, water electrolysis and photoelectrochemical method are not sustainable which emits toxic gases and requires a large amount of energy but in the application of bioreactors the cleaner fuel can be obtained and wastewater can be treated efficiently. The objectives of this review are to estimate the efficiency of reactors involving dark fermentation reactors (suspended and attached growth reactors), photobioreactors (tubular and flat plate reactors) and microbial electrolysis cell bioreactors along with their recent advancements in hydrogen production. This article also highlighted the comprehensive review about the substrate utilization, waste treatment, the principle of reactor process and recent process developments. Although several methods are available for hydrogen production, important and innovative discoveries and process configurations in pilot-scale are needed to estimate the potential of each bioreactor to provide sustainable and cleaner fuel production. Through this review, the present status of bioreactors in hydrogen production and their scale-up opportunities can be determined. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Organometallics  

摘要： In this paper, we describe the facile preparation of a chiral catalyst by the combination of the amino acid, L-proline (Pro), and the enzyme, porcine pancreas lipase (PPL), immobilized on a microporous metal-organic framework (PPL-Pro@MOF). The multipoint immobilization of PPL onto the MOF is made possible with the aid of Pro, which also provided a chiral environment for enhanced enantioselectivity. The application of the microporous MOF is pivotal in maintaining the catalytic activity of PPL, wherein it prevented the leaching of Pro during the catalytic reaction, leading to the enhanced activity of PPL. The prepared biocatalyst was applied in asymmetric carbon-carbon bond formation, demonstrating the potential of this simple approach for chemical transformations.

关键词： Magnetic nanoparticles   Immobilized enzyme   Membrane   Biocatalysis   Fouling  

摘要： The detailed structures and distribution of enzymatically active magnetic-responsive dynamic layers (Enz(SP)) were investigated for the first time in a crossflow superparamagnetic biocatalytic membrane reactor (XF-BMRSP). The trade-off between a higher mass transfer rate, lower fouling tendency, and preventing washout of the dynamic layer, highly depends on the balance of the various forces that act on the Enz(SP). The real-time visual inspection of the biointerface was realized through the design and fabrication of an adapted crossflow system, guided by computational fluid dynamics (CFD) simulations. Time-resolved images of the dynamic layer under a broad range of operational conditions was obtained using fluorescence microscopy. The deposition, dispersion and stability of the dynamic layer was mainly governed by the external magnetic force. The shear force did not cause significant particle washout when a buffer solution was recirculated without permeation even under a turbulent flow regime (6.4 cm/s similar to Re = 5200). The removal of the external magnetic force after initial magnetic immobilization of the Enz(SP), or the substitution of a smooth flow velocity by the propagation of an impulse flow, significantly affected the stability of the dynamic layer. Although membrane fouling occurs at the membrane-solution interface, where a laminar flow regime prevails, most membrane fouling models are based on turbulent flow. Therefore, the detailed, time-resolved images obtained here can provide solid foundation for the development of theoretical models that can describe the membrane fouling under the more representative laminar flow regime.