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关键词： UV-vis spectrum   membrane bioreactor   differential absorbance spectra   absorption coefficient   membrane integrity test  

摘要： In this work, UV-vis absorption spectrum of the membrane integrity analysis based on slopes of log-transformed absorbance spectra, differential absorbance spectroscopy (DAS), and absorption coefficient alpha(254) were studied at different number of breakage fibers and filtration times. Moreover, we analyze the influence of Fe2+ and Ca(2+)concentration on UV spectrum detection results. Cluster analysis and the change ratio R-s were used to determine the dissolved organic matter (DOM) leakage stages. As a result, the correlation coefficient between slope(280-350) value and the number of breakage fibers is 0.901. Seven gaussian bands were successfully model from the DAS, and A4 (312 nm), A5 (339 nm), A6 (367 nm) were chosen to indicate the extent of breakage fiber. Peak 4(A4) is minimally affected by ions concentration. The alpha(254) could be used as a good indicator for detecting industrial wastewater treatment process which correlation coefficient between the number of breakage fibers is 0.955. The DOM leakage process was divided into three stages which were bulk leakage stage, development stage and stabilization stage. The UV-vis absorption spectrum can effectively detect the membrane integrity more sensitive than particle counter and three analyse methods are suitable for different substance in feed water. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Antibiotics   Sponge membrane bioreactor   Hospital wastewater   Microbial community   Deninification   Membrane fouling  

摘要： This study aims to offer insights into how ciprofloxacin (CIP) impact bacterial community structures in the Sponge-MBR process when CIP is spiked into hospital wastewater. We found that the CIP toxicity decreased richness critical phylotypes such as phylum class delta-, beta-, gamma-proteobacteria, and Havobacteria that co-respond to suppress denitrification and cake fouling to 37% and 28% respectively. Cluster analysis shows that the different community structures were formed under the influence of CIP toxicity. CIP decreased attached growth biomass by 2.3 times while increasing the concentration of permeate nitrate by 3.8 times, greatly affecting TN removal by up to 26%. Ammonia removal was kept stable by inflating the ammonia removal rate (p < 0.003), with the wealthy Nitrospira genus guaranteeing the nitrification activity. In addition, we observed an increasing richness of Chloroflexi and Planctornycetes, which may play a role in fouling reduction in the Sponge-MBR. Theretbre, if the amount of antibiotics in hospital wastewater continues to increase, it is so important to extend biomass retention for clenitrification recovery. (C) 2021 Elsevier B.V. All rights reserved.

关键词： Dynamic membranes   Heated aluminum oxide particles (HAOPs)   Membrane bioreactor (MBR) effluent treatment   Effluent organic matter (EfOM)   Reverse osmosis (RO) fouling  

摘要： In this study, a prototype microgranular adsorptive filtration (?GAF) system was constructed employing a 7-bore ceramic membrane as the primary membrane and either heated aluminum oxide particles (HAOPs) or powdered activated carbon (PAC) as the pre-deposited dynamic membrane (DM). The system was used to pre-treat membrane bioreactor (MBR) effluent from a full-scale MBR-reverse osmosis (RO) water reclamation plant. The downstream RO performance and membrane fouling potential of the treated effluent were then assessed. The results indicated that: (i) although PAC removed more overall EfOM than HAOPs did, HAOPs were more effective in removing biopolymers such as polysaccharides and proteins, (ii) HAOPs virtually eliminated fouling of the primary ceramic membrane, whereas considerable fouling (much of it irreversible) occurred when the feed was pretreated with PAC, (iii) HAOPs removed more than 90% of the phosphorus and fluoride from the feed, but PAC removed negligible amounts of these contaminants, and (iv) HAOPs-treated effluent resulted in only a 43% decline in RO permeate water flux over 5 d of continuous filtration, as opposed to 62% flux decline for untreated or PAC-treated effluent. This study thus demonstrates the effectiveness of the HAOPs-based ?GAF process as a pre-treatment for improving downstream RO recovery.

关键词： Dynamic membranes   Dark fermentation   Flux balance analysis (FBA)   Fouling   Biological hydrogen production  

摘要： This study investigates the performance and hidden hydrogen consuming metabolic pathways of a fermentative side stream dynamic membrane (DM) bioreactor using flux balance analysis (FBA). The bioreactor was inoculated with untreated methanogenic seed sludge. It was found that fouling rate aggravated with increasing COD concentration (10-30 g/L) and was positively correlated to it rather than to the applied solid flux on the DM module. Due to increased fouling rate the hydraulic retention time (HRT) could not be reduced less than 0.82 +/- 0.02 d. An increase in the organic loading rate (OLR) led to an increase in H-2 yield from 0.01 to 0.76 mol H-2/mol of sucrose. FBA revealed that homoacetogenesis was the main H-2-consuming pathway at lower OLRs (corresponding to 10 and 15 g COD/L), while for the OLR corresponding to 30 g COD/L, homoacetogens were suppressed. More importantly, caproic acid production pathway was identified for the first time as another H-2-consuming pathway at high OLR which was not significant at lower OLRs during fermentative dynamic membrane bioreactor operations. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Coarse bubble aeration   Denitrification   Membrane fouling   Moving bed membrane bioreactor   Thiobacillus denitrificans  

摘要： In this study, two lab-scale Moving Bed Membrane Bioreactors (MBMBR) were setup and operated in parallel to study the effect of coarse and fine bubble aeration on the performances of membrane filtration and denitrification treating domestic wastewater. The bacterial populations in the two MBMBRs were further analyzed to investigate the mechanisms involved in the different denitrification performances. The results showed that coarse bubble aeration could effectively mitigate membrane fouling by decreasing the formation of cake layer, although smaller sizes of bio-flocs were induced. In addition, coarse bubble aeration could also maintain dissolved oxygen (DO) at a relatively lower level without compromising the moving of bio-carriers, which achieved 10% higher total nitrogen removal rate due to anoxic zone created at inner layers of biofilms on bio-carriers. Accumulation of denitrifier (Thiobacillus denitrificans) on the bio-carriers was found under the coarse bubble aeration system, which can explain its superior denitrification performance. (C) 2021 Elsevier B.V. All rights reserved.

关键词： Membrane bioreactor (MBR)   Cost-benefit analysis   Data envelopment analysis   Technical efficiency   Shadow price  

摘要： While the membrane bioreactor (MBR) technology has been broadly applied to treat wastewater, a rational assessment of its techno-economy is required for its sustainable development. In this study, we performed cost-benefit analysis (CBA) and data envelopment analysis (DEA) of 35 large-scale MBRs (each with a treatment capacity of >= 10,000 m(3)/d). Based on the investment and operation data, we evaluated the marginal cost and environmental benefit (as a function of the shadow prices of pollutants) and hence obtained the net profit (averagely similar to 35 CNY/m(3) or similar to 4.9 USD/m(3)). According to the non-radial directional distance function (NDDF) approach in the DEA framework, the average cost efficiency and energy efficiency of the MBRs were 0.77 and 0.66, respectively. The distributions of the net profit and cost/energy efficiencies significantly varied according to the geographical location, effluent standard, and operating year of the MBRs as indicated by the results of nonparametric tests. Economic panel modeling showed that the cost/energy efficiencies were also affected by external factors such as regional economic level and population density. The techno-economy of MBRs is prominent on occasions of strict effluent standards and underground locations, and could be improved by further technological advancements and policy incentives. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Bioreactors  

摘要： Assimilatory and dissimilatory sulfate reduction (ASR and DSR) are the core bacterial sulfate-reducing pathways involved in wastewater treatment. It has been reported that sulfate-reducing activities could happen within biofoulants of membrane bioreactors during wastewater treatment. Biofoulants are mainly microbial products contributing membrane fouling and subsequent rising energy consumption in driving membrane filtration. Biofoulants from a full-scale biofilm-membrane bioreactor (biofilm-MBR) treating textile wastewater were investigated in this study. During a 10-month operation, sulfate concentrations in the effluent of the biofilm-MBR gradually decreased alongside with the creeping up sulfite concentrations when biofoulants were also building up on membrane modules. Sulfide had no apparent increases in the effluent during this period. Metagenomic analysis revealed diverse microbial communities residing in the biofoulants. Further analysis on their genetic traits revealed abundant ASR's and DSR's functional genes. A plethora of sulfate-reduction bacteria (SRB), including the well-known Desulfovibrio, Desulfainum, Desulfobacca, Desulfobulbus, Desulfococcus, Desulfonema, Desulfosarcina, Desulfobacter, Desulfobacula, Desulfofaba, Desulfotigum, Desulfatibacillum, Desulfatitalea, Desulfobacterium, were detected in the biofoulants. They were believed to play some important carbon and sulfur-cycling roles in our study. Based on metagenomic analysis, we also deduced that ASR was a functionally more important sulfate-reducing route because of the high abundance of assimilatory sulfate reductases detected. Also, the "AMP (adenosine monophosphate)→sulfite" step was a key reaction shared by both ASR and DSR in the biofoulant. This step might be responsible for the sulfite accumulation in the biofilm-MBR effluent. Overall, ASR functional genes in the biofoulants were more abundant. But the bacteria possessing complete DSR pathways caused the sulfide production in the biofi

关键词： Body mass-abundance scaling   Biodegradation   Latitude   Metabolic theory   Riverine ecosystems   Regulating ecosystem service  

摘要： Riverine ecosystems can be conceptualized as 'bioreactors' (the riverine bioreactor) which retain and decompose a wide range of organic substrates. The metabolic performance of the riverine bioreactor is linked to their community structure, the efficiency of energy transfer along food chains, and complex interactions among biotic and abiotic environmental factors. However, our understanding of the mechanistic functioning and capacity of the riverine bioreactor remains limited. We review the state of knowledge and outline major gaps in the understanding of biotic drivers of organic matter decomposition processes that occur in riverine ecosystems, across habitats, temporal dimensions, and latitudes influenced by climate change. We propose a novel, integrative analytical perspective to assess and predict decomposition processes in riverine ecosystems. We then use this model to analyse data to demonstrate that the size-spectra of a community can be used to predict decomposition rates by analysing an illustrative dataset. This modelling methodology allows comparison of the riverine bioreactors performance across habitats and at a global scale. Our integrative analytical approach can be applied to advance understanding of the functioning and efficiency of the riverine bioreactor as hotspots of metabolic activity. Application of insights gained from such analyses could inform the development of strategies that promote the functioning of the riverine bioreactor across global ecosystems. (C) 2021 Elsevier B.V. All rights reserved.