As part of sewage treatment,coagulation could remove phosphorus from the effluent of the Anaerobic-Anoxic-Oxic-Anoxic(A^(2)OA)biological process.The importance in investigating the influence of coagulation on Anaerobi...As part of sewage treatment,coagulation could remove phosphorus from the effluent of the Anaerobic-Anoxic-Oxic-Anoxic(A^(2)OA)biological process.The importance in investigating the influence of coagulation on Anaerobic-Anoxic-Oxic-Anoxic Membrane Bioreactor(A^(2)OA-MBR)should be emphasized.In this study,systematic optimization of coagulation parameters for greater pollutant removal was conducted in terms of coagulant dosage,coagulation residence time and stirring hydraulic conditions.Coagulation process could remarkably remove turbidity,phosphorus,chemical oxygen demand,humic-like,protein-like and polysaccharide-like substances from secondary effluent and A^(2)OA sludge-liquid mixture.Furthermore,the influence of coagulation on membrane fouling development during the ultrafiltration of secondary effluent and A^(2)OA sludge-liquid mixture was investigated based on optimum coagulation parameters.Coagulation simultaneously reduced reversible membrane fouling and the irreversible one by 86%and 16%,respectively.According to excitation-emission matrix and attenuated total reflection-fourier transform infrared spectra,membrane fouling was primarily influenced by the cake layer,although pore fouling might be aggravated by A^(2)OA processes.Besides,the feasibility of coagulation-assisted A^(2)OA-MBRwas also assessed using hollowfibermembranes.It exhibited excellent potential in alleviatingmembrane fouling,while regular cleaning twice a day was not enough to suppress transmembrane pressure increase during direct domestic wastewater ultrafiltration.Additionally,both polysaccharide-like and protein-like foulants were vital components for membrane fouling during wastewater treatment.展开更多
The study of microbial hydrocarbons removal is of great importance for the development of future bioremediation strategies.In this study,we evaluated the removal of a gaseous mixture containing toluene,m-xylene,ethylb...The study of microbial hydrocarbons removal is of great importance for the development of future bioremediation strategies.In this study,we evaluated the removal of a gaseous mixture containing toluene,m-xylene,ethylbenzene,cyclohexane,butane,pentane,hexane and heptane in aerated stirred bioreactors inoculated with Rhodococcus erythropolis and operated under non-sterile conditions.For the real-time measurement of hydrocarbons,a novel systematic approachwas implemented using Selected-Ion Flow TubeMass Spectrometry(SIFTMS).The effect of the carbon source(~9.5 ppmv)on(i)the bioreactors’performance(BR1:dosed with only cyclohexane as a single hydrocarbon versus BR2:dosed with a mixture of the 8 hydrocarbons)and(ii)the evolution of microbial communities over time were investigated.The results showed that cyclohexane reached a maximum removal efficiency(RE)of 53%±4%in BR1.In BR2,almost complete removal of toluene,m-xylene and ethylbenzene,being the most water-soluble and easy-to-degrade carbon sources,was observed.REs below 32%were obtained for the remaining compounds.By exposing the microbial consortium to only the five most recalcitrant hydrocarbons,REs between 45%±5%and 98%±1%were reached.In addition,we observed that airborne microorganisms populated the bioreactors and that the type of carbon source influenced the microbial communities developed.The abundance of species belonging to the genus Rhodococcus was below 10%in all bioreactors at the end of the experiments.This work provides fundamental insights to understand the complex behavior of gaseous hydrocarbon mixtures in bioreactors,along with a systematic approach for the development of SIFT-MS methods.展开更多
Cardiac tissue engineering aims to efficiently replace or repair injured heart tissue using scaffolds,relevant cells,or their combination.While the combination of scaffolds and relevant cells holds the potential to ra...Cardiac tissue engineering aims to efficiently replace or repair injured heart tissue using scaffolds,relevant cells,or their combination.While the combination of scaffolds and relevant cells holds the potential to rapidly remuscularize the heart,thereby avoiding the slow process of cell recruitment,the proper ex vivo cellularization of a scaffold poses a substantial challenge.First,proper diffusion of nutrients and oxygen should be provided to the cell-seeded scaffold.Second,to generate a functional tissue construct,cells can benefit from physiological-like conditions.To meet these challenges,we developed a modular bioreactor for the dynamic cellularization of full-thickness cardiac scaffolds under synchronized mechanical and electrical stimuli.In this unique bioreactor system,we designed a cyclic mechanical load that mimics the left ventricle volume inflation,thus achieving a steady stimulus,as well as an electrical stimulus with an action potential profile to mirror the cells’microenvironment and electrical stimuli in the heart.These mechanical and electrical stimuli were synchronized according to cardiac physiology and regulated by constant feedback.When applied to a seeded thick porcine cardiac extracellular matrix(pcECM)scaffold,these stimuli improved the proliferation of mesenchymal stem/stromal cells(MSCs)and induced the formation of a dense tissue-like structure near the scaffold’s surface.Most importantly,after 35 d of cultivation,the MSCs presented the early cardiac progenitor markers Connexin-43 andα-actinin,which were absent in the control cells.Overall,this research developed a new bioreactor system for cellularizing cardiac scaffolds under cardiac-like conditions,aiming to restore a sustainable dynamic living tissue that can bear the essential cardiac excitation–contraction coupling.展开更多
Bioengineered organs have been seen as a promising strategy to address the shortage of transplantable organs.However,it is still difficult to achieve heterogeneous structures and complex functions similar to natural o...Bioengineered organs have been seen as a promising strategy to address the shortage of transplantable organs.However,it is still difficult to achieve heterogeneous structures and complex functions similar to natural organs using current bioengineering techniques.This work introduces the methods and dilemmas in organ engineering and existing challenges.Furthermore,a new roadmap for organ engineering,which uses a modular strategy with autologous bioreactors to create organ-level bioengineered constructions,is summarized based on the latest research advances.In brief,different functional modules of natural organs are constructed in vitro,and autologous bioreactors in vivo are utilized to facilitate inter-module assembly to form a complete bioengineered organ capable of replacing natural organ functions.There are bioengineered organs,such as biomimetic tracheas,which have been successfully fabricated following this roadmap.This new roadmap for organ engineering shows prospects in addressing the shortage of transplantable organs and has broad prospects for clinical applications.展开更多
A pilot plant integrating pervaporation membrane bioreactor and mechanical vapor compression for bioethanol production was designed and constructed in the study,with a bioethanol production of 300 t·a^(-1).Key eq...A pilot plant integrating pervaporation membrane bioreactor and mechanical vapor compression for bioethanol production was designed and constructed in the study,with a bioethanol production of 300 t·a^(-1).Key equipment in the process were designed based on bench test data.A pilot-scale fermenter with 20 m^(3) in volume,4 m in height and 2.5 m in diameter was designed based on geometric similarity criterion and power equality criterion.An integrated plate-frame membrane module with 105 plates was newly developed.Compared with conventional batch fermentation,the improvement of equipment utilization efficiency and the cell utilization efficiency can be expected as 1.5-2.0 times and 2-10 times,respectively,with waste water reduced by 70% to 85%.The high-exergy energy requirement for pilot plant was 57.5 k W,of which the broth preheater occupied 85.7%,following by the compressor 1.1%,pump1.9% and fermenter agitator 0.3%.The total energy requirement including distillation for producing 1 kg ethanol(95%(mass)) achieved an energy surplus of 15.6 MJ.展开更多
This work established a quantitative method to access the shear stability of aerobic granular sludge(AGS)and validated its feasibility by using the mature AGS from a pilot-scale(50 tons/day)membrane bioreactor(MBR)for...This work established a quantitative method to access the shear stability of aerobic granular sludge(AGS)and validated its feasibility by using the mature AGS from a pilot-scale(50 tons/day)membrane bioreactor(MBR)for treating real municipal wastewater.The results showed that the changing rate( S)of the peak area(S)of granule size distribution(GSD)exhibited an exponential relationship(R^(2)≥0.76)with the shear time(y=a−b·c^(x)),which was a suitable indicative index to reflect the shear stability of different AGS samples.The limiting granule size(LGS)was defined and proposed to characterize the equilibrium size for AGS after being sheared for a period of time,whose value in terms of Dv50 showed high correlation(R^(2)=0.92)with the parameter a.The free Ca^(2+)(28.44-34.21 mg/L)in the influent specifically interacted with polysaccharides(PS)in the granule’s extracellular polymeric substance(EPS)as a nucleation site,thereby inducing the formation of Ca precipitation to enhance its Young’s modulus,while Ca^(2+) primarily interacted with PS in soluble metabolic product(SMP)during the initial granulation process.Furthermore,the Young’s modulus significantly affected the parameter a related to shear stability(R^(2)=0.99).Since the parameter a was more closely related(R^(2)=1.00)to S than that of the parameter b or c,the excellent correlation(R^(2)=0.99)between the parameter a and the wet density further verified the feasibility of this method.展开更多
Bioreactors are used to dynamically condition engineered tissues to achieve the required degree of maturation before in vivo implantation.Integrating sensors and imaging capabilities into bioreactors can help us under...Bioreactors are used to dynamically condition engineered tissues to achieve the required degree of maturation before in vivo implantation.Integrating sensors and imaging capabilities into bioreactors can help us understand how the culture environment influences tissue maturation and growth.Additionally,this enables the monitoring of tissue constructs and provides critical information for quality control.This study aimed to develop a standardized,self-contained,uniaxial bioreactor module for the clinical manufacturing of tissue constructs;this system would benefit from unidirectional mechanical or electrical stimulation,or both.We achieved this goal by integrating stimulation and sensing components that provide an optimal culture environment and monitoring capabilities to improve tissue manufacturing.The uniaxial bioreactor module included integrated,user-friendly mechanical and electrical stimulations with force measurement to enhance the preconditioning of the engineered tissues.Also,a sensor loop and media exchange system were integrated to monitor the culture environment and cellular metabolites over time,and the camera system above the tissue construct enabled the macroscopic visualization of tissue maturation.Furthermore,the onboard media exchange system was programmed into the module to maintain aseptic culture conditions in the long term.Subsequently,using native skeletal muscle tissue and tissue-engineered skeletal muscle constructs,the performance of the uniaxial bioreactor module was validated for its application in preconditioning and enhancing tissue maturation.展开更多
Two-phase partitioning bioreactors(TPPBs)have been widely used because they overcome the mass-transfer limitation of hydrophobic volatile organic compounds(VOCs)in waste gas biological treatments.Understanding the mec...Two-phase partitioning bioreactors(TPPBs)have been widely used because they overcome the mass-transfer limitation of hydrophobic volatile organic compounds(VOCs)in waste gas biological treatments.Understanding the mechanisms of mass-transfer enhancement in TPPBs would enable efficient predictions for further industrial applications.In this study,influences of gradually increasing silicone oil ratio on the TPPB was explored,and a 94.35%reduction of the n-hexane partition coefficient was observed with 0.1 vol.%silicone,which increased to 80.7%along with a 40-fold removal efficiency enhancement in the stabilised removal period.The elimination capacity increased from 1.47 to 148.35 g/(m^(3)·h),i.e.a 101-fold increase compared with that of the single-phase reactors,when 10 vol.%(3 Critical Micelle Concentration)silicone oil was added.The significantly promoted partition coefficient was the main reason for the mass transfer enhancement,which covered the negative influences of the decreased total mass-transfer coefficient with increasing silicone oil volume ratio.The gradually rising stirring rate was benefit to the n-hexane removal,which became negative when the dominant resistance shifted from mass transfer to biodegradation.Moreover,a mass-transfer-reaction kinetic model of the TPPB was constructed based on the balance of n-hexane concentration,dissolved oxygen and biomass.Similar to the mechanism,the partition factor was predicted sensitive to the removal performance,and another five sensitive parameters were found simultaneously.This forecasting method enables the optimisation of TPPB performance and provides theoretical support for hydrophobic VOCs degradation.展开更多
Membrane fouling remains the primary economic barrier to the widespread implementation of membrane bioreactors (MBRs), despite the fact that they lead to the production of high-quality effluent. Operational conditions...Membrane fouling remains the primary economic barrier to the widespread implementation of membrane bioreactors (MBRs), despite the fact that they lead to the production of high-quality effluent. Operational conditions are critical factors influencing membrane fouling. This study aimed to investigate the simultaneous impacts of temperature and hydraulic retention time (HRT) variations on membrane fouling. Experiments were conducted at three different temperatures (18°C, 25°C, and 32°C) and HRTs (6 h, 9 h, and 15 h). The results demonstrated that increases in both temperature and HRT contributed to a reduction in membrane fouling. Additionally, a positive interaction between temperature and HRT was observed in the linear slope variation of membrane permeation, with temperature variations exerting a greater influence on membrane fouling than HRT variations. Fouling factor analysis revealed that increases in temperature and HRT led to decreased concentrations of soluble microbial products (SMP) and extracellular polymeric substances (EPS), particularly carbohydrates, in the activated sludge. Analyses of the cake layer of the membrane indicated that increasing temperature and HRT reduced EPS levels, particularly polysaccharides and proteins;altered primary protein structure;and increased the mean particle size distribution. Ultimately, these changes led to reductions in both reversible and irreversible hydraulic resistances. This study highlights the importance of optimizing operational parameters such as temperature and HRT to enhance membrane performance and treatment efficiency in MBR systems while mitigating fouling.展开更多
The structural and operational optimization of gas-liquid stirred bioreactors presents both complexity and critical importance for enhancing mass transfer performance. This study proposes a machine learning (ML)-drive...The structural and operational optimization of gas-liquid stirred bioreactors presents both complexity and critical importance for enhancing mass transfer performance. This study proposes a machine learning (ML)-driven approach to identify key features and predict the volumetric mass transfer coefficient (kLa). Four ML models were adopted and compared for kLa prediction in Newtonian and non-Newtonian fluids by evaluative indices, with CatBoost and XGBoost emerging as the optimal models, respectively. Specifically, it is demonstrated that Catboost has higher prediction accuracy (AARD = 18.84%) than empirical equations by effectively incorporating multidimensional features (structural, impeller, and operational), while simultaneously extending applicability to diverse Newtonian fluids. For non-Newtonian fluids, XGBoost outperforms empirical equations by effectively incorporating fluid rheological parameters (consistency coefficient, power-law index), thereby better capturing shear-thinning behavior. Feature importance analysis further identified rotational speed (for Newtonian fluids) and liquid height (for non-Newtonian fluids) as the key features, while 2D partial dependence analysis establishes quantitative optimization ranges. This ML approach provides an efficient predictive tool for gas-liquid stirred bioreactor design and optimization.展开更多
Woodchip bioreactors are an eco-friendly technology for removing nitrogen(N)pollution.However,there needs to be more clarity regarding the dissolved organicmatter(DOM)characteristics and bacterial community succession...Woodchip bioreactors are an eco-friendly technology for removing nitrogen(N)pollution.However,there needs to be more clarity regarding the dissolved organicmatter(DOM)characteristics and bacterial community succession mechanisms and their association with the N removal performance of bioreactors.The laboratory woodchip bioreactors were continuously operated for 360 days under three influent N level treatments,and the results showed that the average removal rate of TN was 45.80 g N/(m^(3)·day)when the influent N level was 100 mg N/L,which was better than 10 mg N/L and 50 mg N/L.Dynamic succession of bacterial communities in response to influent N levels and DOM characteristics was an important driver of TN removal rates.Medium to high N levels enriched a copiotroph bacterial module(Module 1)detected by network analysis,including Phenylobacterium,Xanthobacteraceae,Burkholderiaceae,Pseudomonas,and Magnetospirillaceae,carrying N-cycle related genes for denitrification and ammonia assimilation by the rapid consumption of DOM.Such a process can increase carbon limitation to stimulate local organic carbon decomposition to enrich oligotrophswith fewer N-cycle potentials(Module 2).Together,this study reveals that the compositional change ofDOMand bacterial community succession are closely related to N removal performance,providing an ecological basis for developing techniques for N-rich effluent treatment.展开更多
A biochar-assisted anaerobic membrane bioreactor(BC-AnMBR)was conducted to evaluate the performance in treating swine wastewater with different organic loading rates(OLR)ranging from 0.38 to 1.13 kg-COD/(m3.d).Results...A biochar-assisted anaerobic membrane bioreactor(BC-AnMBR)was conducted to evaluate the performance in treating swine wastewater with different organic loading rates(OLR)ranging from 0.38 to 1.13 kg-COD/(m3.d).Results indicated that adding spent coffee grounds biochar(SCG-BC)improved the organic removal efficiency compared to the conventional AnMBR,with an overall COD removal rate of>95.01%.Meanwhile,methane production of up to 0.22 LCH4/gCOD with an improvement of 45.45%was achieved under a high OLR of 1.13 kg-COD/(m3.d).Furthermore,the transmembrane pressure(TMP)in the BC-AnMBR system was stable at 4.5 kPa,and no irreversible membrane fouling occurred within 125 days.Microbial community analysis revealed that the addition of SCG-BC increased the relative abundance of autotrophic methanogenic archaea,particularly Methanosarcina(from 0.11%to 11.16%)and Methanothrix(from 16.34%to 24.05%).More importantly,Desulfobacterota and Firmicutes phylum with direct interspecific electron transfer(DIET)capabilities were also enriched with autotrophic methanogens.Analysis of the electron transfer pathway showed that the concentration of c-type cytochromes increased by 38.60%in the presence of SCGBC,and thus facilitated the establishment of DIET and maintained high activity of the elec-tron transfer system even at high OLR.In short,the BC-AnMBR system performs well under various OLR conditions and is stable in the recovery energy system for swine wastewater.展开更多
A new type of membrane bioreactor named 'airliftmembrane-bioreactor' is discussed. For municipal wastewaterreclamation, the preliminary study on airlift membrane-bioreactorshows its good performance such as hi...A new type of membrane bioreactor named 'airliftmembrane-bioreactor' is discussed. For municipal wastewaterreclamation, the preliminary study on airlift membrane-bioreactorshows its good performance such as higher flux and lower energyconsumption. The airlift membrane-bioreactor is potentiallyapplicable in bioengineer- ing and environmental protection fields.展开更多
Experiments on treatment of domestic wastewater by membrane bioreactors were carried out.The results showed that this process could produce good quality effluent with low COD,turbidity and total count of bacteria.With...Experiments on treatment of domestic wastewater by membrane bioreactors were carried out.The results showed that this process could produce good quality effluent with low COD,turbidity and total count of bacteria.With intermittent operation and continuous aeration,the membrane flux was kept steady.The mechanisms of removing COD through membrane,the structure of membrane and filtration resistance were also discussed.展开更多
We aimed to investigate the composition and phylogenetic rela-tionships of the viable but non-culturable （VBNC） state bacteria in pharmaceutical wastewater. [Method] Soil filter was used for constructing bioreactor....We aimed to investigate the composition and phylogenetic rela-tionships of the viable but non-culturable （VBNC） state bacteria in pharmaceutical wastewater. [Method] Soil filter was used for constructing bioreactor. Based on the resuscitation- and growth-promoting function of Resuscitation Promoting Factor （Rpf） for VBNC bacteria, VBNC bacteria were isolated by most probable number （MPN） method and dilution-plating method and 16S rRNA gene phylogenetic analysis was carried out. [Result] In MPN culture system, Rpf could promote the resuscitation and growth of some bacteria. There were VBNC advantage floras that sensitive to Rpf in pharmaceutical wastewater. The culturable VBNC bacteria in pharmaceutical wastewater consisted of high-GC gram-positive actinomycetes including genera Mi-crobacterium, Gordonia and Leucobacter, and gram-negative bacteria including gen-era Candidimonas, Xanthobacter and Aminobacter. Four strains （ZYM1, ZYM3, ZYZR4, ZYXR1） could be potential novel species. [Conclusion] This research re-vealed there were VBNC bacteria in pharmaceutical wastewater. These results could provide important ideas and methods for further studies on VBNC bacteria in the pharmaceutical wastewater, especial y the formation mechanism and recovery mech-anism of VBNC bacteria and the advanced degradation process improvement of pharmaceutical wastewater.展开更多
The performance of combined Fenton oxidation and membrane bioreactor （MBR） process for the advanced treatment of an effluent from an integrated dyeing wastewater treatment plant was evaluated. The experimental resul...The performance of combined Fenton oxidation and membrane bioreactor （MBR） process for the advanced treatment of an effluent from an integrated dyeing wastewater treatment plant was evaluated. The experimental results revealed that under the optimum Fenton oxidation conditions （initial pH 5, H 2 O 2 dosage 17 mmol/L, and Fe^ 2＋ 1.7 mmol/L） the average total organic carbon （TOC） and color removal ratios were 39.3% and 69.5% after 35 min of reaction, respectively. Results from Zahn-Wallens Test also represented that Fenton process was effective to enhance the biodegradability of the test wastewater. As for the further purification of MBR process, TOC removal capacity was examined at different hydraulic retention times （HRT） of 10, 18 and 25 hr. Under the optimum HRT of 18 hr, the average TOC concentration and color of the final MBR effluent were 16.8 mg/L and 2 dilution time, respectively. The sludge yield coefficient was 0.13 g MLSS/g TOC and TOC degradation rate was 0.078 kg TOC/（m ^3 ·day）. The final effluent of MBR can meet the reuse criteria of urban recycling water – water quality standard for miscellaneous water consumption GBT18920-2002.展开更多
The effects of powdered activated carbon(PAC) addition on sludge morphological, aggregative and microbial properties in a dynamic membrane bioreactor(DMBR) were investigated to explore the enhancement mechanism of pol...The effects of powdered activated carbon(PAC) addition on sludge morphological, aggregative and microbial properties in a dynamic membrane bioreactor(DMBR) were investigated to explore the enhancement mechanism of pollutants removal and filtration performance. Sludge properties were analyzed through various analytical measurements. The results showed that the improved sludge aggregation ability and the evolution of microbial communities affected sludge morphology in PAC-DMBR, as evidenced by the formation of large, regularly shaped and strengthened sludge flocs. The modifications of sludge characteristics promoted the formation process and filtration flux of the dynamic membrane(DM) layer. Additionally, PAC addition did not exert very significant influence on the propagation of eukaryotes(protists and metazoans)and microbial metabolic activity. High-throughput pyrosequencing results indicated that adding PAC improved the bacterial diversity in activated sludge, as PAC addition brought about additional microenvironment in the form of biological PAC(BPAC), which promoted the enrichment of Acinetobacter(13.9%), Comamonas(2.9%), Flavobacterium(0.31%) and Pseudomonas(0.62%), all contributing to sludge flocs formation and several(such as Acinetobacter) capable of biodegrading relatively complex organics. Therefore, PAC addition could favorably modify sludge properties from various aspects and thus enhance the DMBR performance.展开更多
The anaerobic ammonia oxidation(Anammox) bioreactor was successfully started up with the nitrifying activated sludge. After anaerobically operated for 105 d, the bioreactor reached a good performance with removal perc...The anaerobic ammonia oxidation(Anammox) bioreactor was successfully started up with the nitrifying activated sludge. After anaerobically operated for 105 d, the bioreactor reached a good performance with removal percentage of both ammonia and nitrite higher than 95% and volumetric total nitrogen removal as high as 149.55 mmol/(L·d). The soft padding made an important contribution to the high efficiency and stability because it held a large amount of biomass in the bioreactor.展开更多
Population development of key groups of anaerobic and aerobic bacteria involved in municipal refuse decomposition under laboratory landfill bioreactors with and without leachate recycle and inoculation was measured si...Population development of key groups of anaerobic and aerobic bacteria involved in municipal refuse decomposition under laboratory landfill bioreactors with and without leachate recycle and inoculation was measured since modeling municipal refuse was landfilled in bioreactors for about 210 days. Hydrolytic fermentative bacteria (HFB), hydrogen-producing acetogenic bacteria (HPAB), methane-producing bacteria (MPB), sulfate-reducing bacteria (SRB), anaerobic and aerobic cellulolytic bacteria and denitrabacteria were enumerated by the most probable number technique. The results showed that the dominant microorganism groups were the methanogenic bacteria including hydrolytic fermentative, hydrogen-producing acetogenic and methane-producing bacteria. They were present in fresh refuse but at low values and positively affected by leachate recycle and refuse inoculation. The amounts of HFB or HPAB in digesters D4 and D5 operated with inoculation and leachate recycle reached their maximum values of 1010 - 1012 cells/g dry refuse for HFB or 105 - 106 cells/g dry refuse for HPAB on day 60, in digester D3 operated with leachate recycle on day 120 for HFB (109 cells/g dry refuse) or on day 90 for HPAB (105 cells/g dry refuse), and in digesters D1 and D2 on day 210 for HFB (109 cells/g dry refuse) or on day 90 for HPAB (104 - 106 cells/g dry refuse). The population of methane-producing bacteria in digesters D4 and D5 sharply increased on days 60 and 90 respectively, however in digesters D1, D2 and D3 on day 120. Leachate recycle and inoculation changed the cellulolytic microorganisms composition of refuse ecosystem, the higher amounts of anaerobic cellulolytic bacteria were measured in digesters D4 and D5 (107 cells/g dry refuse), followed by digesters D3 (106 cells/g dry refuse), D2 or D1 (104 cells/g dry refuse). However, the amounts of aerobic cellulolytic bacteria were much lower than that of anaerobic cellulolytic bacteria. And it was higher in digesters D3 than those in digesters D1, D2, D4 and D5. The amounts of SRB and denitrabacteria were also higher in digester D5 than those in digesters D1, D2, D3 and D4. Refuse decomposition could be accelerated by leachate recycle and inoculation in the view of microorganism development.展开更多
Three identical membrane bioreactors （MBRs） were operated over 2 years at different sludge retention time （SRT） of 10 d, 40 d and no sludge withdrawal （NS）, to elucidate and quantify the effect of SRT on the slu...Three identical membrane bioreactors （MBRs） were operated over 2 years at different sludge retention time （SRT） of 10 d, 40 d and no sludge withdrawal （NS）, to elucidate and quantify the effect of SRT on the sludge characteristics and membrane fouling. The hydraulic retention times of these MBRs were controlled at 12 h. With increasing SRT, the sludge concentrations in the MBRs increased, whereas the ratio of volatile suspended solid to the total solid decreased, and the size of sludge granule diminished in the meantime. A higher sludge concentration at long SRT could maintain a better organic removal efficiency, and a longer SRT was propitious to the growth of nitrifiers. The performance of these MBRs for the removal of COD and NH4^＋-N did not change much with different SRTs. However, the bioactivity decreased as SRT increase. The measurement of specific oxygen uptake rates （SOUR） and fluorescence in situ hybridization （FISH） with rRNA-targeted oligonucleotide probes testified that SOUR and the proportion of the bacteria-specific probe EUB338 in all DAPI-stainable bacteria decreased with increasing SRT. The concentrations of total organic carbon, protein, polysaccharides and soluble extracellular polymeric substance （EPS） in the mixed liquor supernatant also decreased with increasing SRT. The membrane fouling rate was higher at shorter SRT, and the highest fouling rate appeared at a SRT of 10 d. Both the sludge cake layer and gel layer had contribution to the fouling resistance, but the relative contribution of the gel layer decreased as SRT increase.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52170070,52400022 and 52200088)the Youth S&T Talent Support Programme of Guangdong Provincial Association for Science and Technology(GDSTA)(No.SKXRC202406)+1 种基金China Postdoctoral Science Foundation(No.2023M740754)“One hundred Youth”Science and Technology Plan,Guangdong University of Technology,China(No.263113906).
文摘As part of sewage treatment,coagulation could remove phosphorus from the effluent of the Anaerobic-Anoxic-Oxic-Anoxic(A^(2)OA)biological process.The importance in investigating the influence of coagulation on Anaerobic-Anoxic-Oxic-Anoxic Membrane Bioreactor(A^(2)OA-MBR)should be emphasized.In this study,systematic optimization of coagulation parameters for greater pollutant removal was conducted in terms of coagulant dosage,coagulation residence time and stirring hydraulic conditions.Coagulation process could remarkably remove turbidity,phosphorus,chemical oxygen demand,humic-like,protein-like and polysaccharide-like substances from secondary effluent and A^(2)OA sludge-liquid mixture.Furthermore,the influence of coagulation on membrane fouling development during the ultrafiltration of secondary effluent and A^(2)OA sludge-liquid mixture was investigated based on optimum coagulation parameters.Coagulation simultaneously reduced reversible membrane fouling and the irreversible one by 86%and 16%,respectively.According to excitation-emission matrix and attenuated total reflection-fourier transform infrared spectra,membrane fouling was primarily influenced by the cake layer,although pore fouling might be aggravated by A^(2)OA processes.Besides,the feasibility of coagulation-assisted A^(2)OA-MBRwas also assessed using hollowfibermembranes.It exhibited excellent potential in alleviatingmembrane fouling,while regular cleaning twice a day was not enough to suppress transmembrane pressure increase during direct domestic wastewater ultrafiltration.Additionally,both polysaccharide-like and protein-like foulants were vital components for membrane fouling during wastewater treatment.
基金supported by Ghent University through a special research grant(No.BOFSTG2019005701)The assistance provided by Ann Dirckx in the microbiology lab was greatly appreciated.Allan A.Alvarado-Alvarado thanks the European Commission under the Erasmus+EMJMD Program for funding his research at Ghent University(No.2017-1957/001-001-EMJMD).
文摘The study of microbial hydrocarbons removal is of great importance for the development of future bioremediation strategies.In this study,we evaluated the removal of a gaseous mixture containing toluene,m-xylene,ethylbenzene,cyclohexane,butane,pentane,hexane and heptane in aerated stirred bioreactors inoculated with Rhodococcus erythropolis and operated under non-sterile conditions.For the real-time measurement of hydrocarbons,a novel systematic approachwas implemented using Selected-Ion Flow TubeMass Spectrometry(SIFTMS).The effect of the carbon source(~9.5 ppmv)on(i)the bioreactors’performance(BR1:dosed with only cyclohexane as a single hydrocarbon versus BR2:dosed with a mixture of the 8 hydrocarbons)and(ii)the evolution of microbial communities over time were investigated.The results showed that cyclohexane reached a maximum removal efficiency(RE)of 53%±4%in BR1.In BR2,almost complete removal of toluene,m-xylene and ethylbenzene,being the most water-soluble and easy-to-degrade carbon sources,was observed.REs below 32%were obtained for the remaining compounds.By exposing the microbial consortium to only the five most recalcitrant hydrocarbons,REs between 45%±5%and 98%±1%were reached.In addition,we observed that airborne microorganisms populated the bioreactors and that the type of carbon source influenced the microbial communities developed.The abundance of species belonging to the genus Rhodococcus was below 10%in all bioreactors at the end of the experiments.This work provides fundamental insights to understand the complex behavior of gaseous hydrocarbon mixtures in bioreactors,along with a systematic approach for the development of SIFT-MS methods.
基金funded by the Israeli Ministry of Innovation,Science and Technology(Grant No.3-11873)the Israel Science Foundation(Grant No.1563/10)+1 种基金the Randy L.and Melvin R.Berlin Family Research Center for Regenerative Medicinethe Gurwin Family Foundation.
文摘Cardiac tissue engineering aims to efficiently replace or repair injured heart tissue using scaffolds,relevant cells,or their combination.While the combination of scaffolds and relevant cells holds the potential to rapidly remuscularize the heart,thereby avoiding the slow process of cell recruitment,the proper ex vivo cellularization of a scaffold poses a substantial challenge.First,proper diffusion of nutrients and oxygen should be provided to the cell-seeded scaffold.Second,to generate a functional tissue construct,cells can benefit from physiological-like conditions.To meet these challenges,we developed a modular bioreactor for the dynamic cellularization of full-thickness cardiac scaffolds under synchronized mechanical and electrical stimuli.In this unique bioreactor system,we designed a cyclic mechanical load that mimics the left ventricle volume inflation,thus achieving a steady stimulus,as well as an electrical stimulus with an action potential profile to mirror the cells’microenvironment and electrical stimuli in the heart.These mechanical and electrical stimuli were synchronized according to cardiac physiology and regulated by constant feedback.When applied to a seeded thick porcine cardiac extracellular matrix(pcECM)scaffold,these stimuli improved the proliferation of mesenchymal stem/stromal cells(MSCs)and induced the formation of a dense tissue-like structure near the scaffold’s surface.Most importantly,after 35 d of cultivation,the MSCs presented the early cardiac progenitor markers Connexin-43 andα-actinin,which were absent in the control cells.Overall,this research developed a new bioreactor system for cellularizing cardiac scaffolds under cardiac-like conditions,aiming to restore a sustainable dynamic living tissue that can bear the essential cardiac excitation–contraction coupling.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.81770091,82000099)the National Key Research and Development Program of China(Nos.2024YFC3044600,2022YFC2407400)+6 种基金the Clinical Research Plan of Shanghai Hospital Development Center(multi-center clinical research project for major diseases)(No.SHDC2020CR1021B)the scientific and technological innovation action plan of Science and Technology Commission of Shanghai Municipality(No.20DZ2253700)the Science and Technology Commission of Shanghai Municipality(Nos.20YF1440900,21YF1438500,21S31905200)the Clinical Research Foundation of Shanghai Pulmonary Hospital(Nos.FKLY20007,SKPY2021005)Shanghai Pulmonary Hospital Innovation Team(Nos.FKXY2306,FKCX1906,FKXY1902)Shanghai Pulmonary Hospital Grant(No.FKCY1903)Ningbo Top Medical and Health Research Program(No.2022030208)。
文摘Bioengineered organs have been seen as a promising strategy to address the shortage of transplantable organs.However,it is still difficult to achieve heterogeneous structures and complex functions similar to natural organs using current bioengineering techniques.This work introduces the methods and dilemmas in organ engineering and existing challenges.Furthermore,a new roadmap for organ engineering,which uses a modular strategy with autologous bioreactors to create organ-level bioengineered constructions,is summarized based on the latest research advances.In brief,different functional modules of natural organs are constructed in vitro,and autologous bioreactors in vivo are utilized to facilitate inter-module assembly to form a complete bioengineered organ capable of replacing natural organ functions.There are bioengineered organs,such as biomimetic tracheas,which have been successfully fabricated following this roadmap.This new roadmap for organ engineering shows prospects in addressing the shortage of transplantable organs and has broad prospects for clinical applications.
基金supported by the National Key Research and Development Program of China(2021YFC2101204)the Natural Science Foundation of Sichuan Province(2025ZNSFSC0926)the Fundamental Research Funds for the Central Universities(2023SCU12080 and 20822041B4013)。
文摘A pilot plant integrating pervaporation membrane bioreactor and mechanical vapor compression for bioethanol production was designed and constructed in the study,with a bioethanol production of 300 t·a^(-1).Key equipment in the process were designed based on bench test data.A pilot-scale fermenter with 20 m^(3) in volume,4 m in height and 2.5 m in diameter was designed based on geometric similarity criterion and power equality criterion.An integrated plate-frame membrane module with 105 plates was newly developed.Compared with conventional batch fermentation,the improvement of equipment utilization efficiency and the cell utilization efficiency can be expected as 1.5-2.0 times and 2-10 times,respectively,with waste water reduced by 70% to 85%.The high-exergy energy requirement for pilot plant was 57.5 k W,of which the broth preheater occupied 85.7%,following by the compressor 1.1%,pump1.9% and fermenter agitator 0.3%.The total energy requirement including distillation for producing 1 kg ethanol(95%(mass)) achieved an energy surplus of 15.6 MJ.
基金supported by the Key Technologies Research and Development Program of Guangzhou (No.2023B03J1284)Guangdong Yuehai Water Investment Co.,Ltd. (No.CC80-QT01-2020-0010).
文摘This work established a quantitative method to access the shear stability of aerobic granular sludge(AGS)and validated its feasibility by using the mature AGS from a pilot-scale(50 tons/day)membrane bioreactor(MBR)for treating real municipal wastewater.The results showed that the changing rate( S)of the peak area(S)of granule size distribution(GSD)exhibited an exponential relationship(R^(2)≥0.76)with the shear time(y=a−b·c^(x)),which was a suitable indicative index to reflect the shear stability of different AGS samples.The limiting granule size(LGS)was defined and proposed to characterize the equilibrium size for AGS after being sheared for a period of time,whose value in terms of Dv50 showed high correlation(R^(2)=0.92)with the parameter a.The free Ca^(2+)(28.44-34.21 mg/L)in the influent specifically interacted with polysaccharides(PS)in the granule’s extracellular polymeric substance(EPS)as a nucleation site,thereby inducing the formation of Ca precipitation to enhance its Young’s modulus,while Ca^(2+) primarily interacted with PS in soluble metabolic product(SMP)during the initial granulation process.Furthermore,the Young’s modulus significantly affected the parameter a related to shear stability(R^(2)=0.99).Since the parameter a was more closely related(R^(2)=1.00)to S than that of the parameter b or c,the excellent correlation(R^(2)=0.99)between the parameter a and the wet density further verified the feasibility of this method.
基金possible by the US Army Medical Research and Development Command through the Medical Technology Enterprise Consortium under Contract#W81XWH-15-9-0001.
文摘Bioreactors are used to dynamically condition engineered tissues to achieve the required degree of maturation before in vivo implantation.Integrating sensors and imaging capabilities into bioreactors can help us understand how the culture environment influences tissue maturation and growth.Additionally,this enables the monitoring of tissue constructs and provides critical information for quality control.This study aimed to develop a standardized,self-contained,uniaxial bioreactor module for the clinical manufacturing of tissue constructs;this system would benefit from unidirectional mechanical or electrical stimulation,or both.We achieved this goal by integrating stimulation and sensing components that provide an optimal culture environment and monitoring capabilities to improve tissue manufacturing.The uniaxial bioreactor module included integrated,user-friendly mechanical and electrical stimulations with force measurement to enhance the preconditioning of the engineered tissues.Also,a sensor loop and media exchange system were integrated to monitor the culture environment and cellular metabolites over time,and the camera system above the tissue construct enabled the macroscopic visualization of tissue maturation.Furthermore,the onboard media exchange system was programmed into the module to maintain aseptic culture conditions in the long term.Subsequently,using native skeletal muscle tissue and tissue-engineered skeletal muscle constructs,the performance of the uniaxial bioreactor module was validated for its application in preconditioning and enhancing tissue maturation.
基金supported by the National Key Research and Development Program of China(No.2022YFC3702000)the National Natural Science Foundation of China(No.52070169)the Project of Bureau of Science and Technology of Zhoushan,China(No.2022C41013).
文摘Two-phase partitioning bioreactors(TPPBs)have been widely used because they overcome the mass-transfer limitation of hydrophobic volatile organic compounds(VOCs)in waste gas biological treatments.Understanding the mechanisms of mass-transfer enhancement in TPPBs would enable efficient predictions for further industrial applications.In this study,influences of gradually increasing silicone oil ratio on the TPPB was explored,and a 94.35%reduction of the n-hexane partition coefficient was observed with 0.1 vol.%silicone,which increased to 80.7%along with a 40-fold removal efficiency enhancement in the stabilised removal period.The elimination capacity increased from 1.47 to 148.35 g/(m^(3)·h),i.e.a 101-fold increase compared with that of the single-phase reactors,when 10 vol.%(3 Critical Micelle Concentration)silicone oil was added.The significantly promoted partition coefficient was the main reason for the mass transfer enhancement,which covered the negative influences of the decreased total mass-transfer coefficient with increasing silicone oil volume ratio.The gradually rising stirring rate was benefit to the n-hexane removal,which became negative when the dominant resistance shifted from mass transfer to biodegradation.Moreover,a mass-transfer-reaction kinetic model of the TPPB was constructed based on the balance of n-hexane concentration,dissolved oxygen and biomass.Similar to the mechanism,the partition factor was predicted sensitive to the removal performance,and another five sensitive parameters were found simultaneously.This forecasting method enables the optimisation of TPPB performance and provides theoretical support for hydrophobic VOCs degradation.
文摘Membrane fouling remains the primary economic barrier to the widespread implementation of membrane bioreactors (MBRs), despite the fact that they lead to the production of high-quality effluent. Operational conditions are critical factors influencing membrane fouling. This study aimed to investigate the simultaneous impacts of temperature and hydraulic retention time (HRT) variations on membrane fouling. Experiments were conducted at three different temperatures (18°C, 25°C, and 32°C) and HRTs (6 h, 9 h, and 15 h). The results demonstrated that increases in both temperature and HRT contributed to a reduction in membrane fouling. Additionally, a positive interaction between temperature and HRT was observed in the linear slope variation of membrane permeation, with temperature variations exerting a greater influence on membrane fouling than HRT variations. Fouling factor analysis revealed that increases in temperature and HRT led to decreased concentrations of soluble microbial products (SMP) and extracellular polymeric substances (EPS), particularly carbohydrates, in the activated sludge. Analyses of the cake layer of the membrane indicated that increasing temperature and HRT reduced EPS levels, particularly polysaccharides and proteins;altered primary protein structure;and increased the mean particle size distribution. Ultimately, these changes led to reductions in both reversible and irreversible hydraulic resistances. This study highlights the importance of optimizing operational parameters such as temperature and HRT to enhance membrane performance and treatment efficiency in MBR systems while mitigating fouling.
基金supported by the National Natural Science Foundation of China(22494713,22178160,22327809 and 22208141)Natural Science Foundation of Jiangsu Province,China(BK20220349).
文摘The structural and operational optimization of gas-liquid stirred bioreactors presents both complexity and critical importance for enhancing mass transfer performance. This study proposes a machine learning (ML)-driven approach to identify key features and predict the volumetric mass transfer coefficient (kLa). Four ML models were adopted and compared for kLa prediction in Newtonian and non-Newtonian fluids by evaluative indices, with CatBoost and XGBoost emerging as the optimal models, respectively. Specifically, it is demonstrated that Catboost has higher prediction accuracy (AARD = 18.84%) than empirical equations by effectively incorporating multidimensional features (structural, impeller, and operational), while simultaneously extending applicability to diverse Newtonian fluids. For non-Newtonian fluids, XGBoost outperforms empirical equations by effectively incorporating fluid rheological parameters (consistency coefficient, power-law index), thereby better capturing shear-thinning behavior. Feature importance analysis further identified rotational speed (for Newtonian fluids) and liquid height (for non-Newtonian fluids) as the key features, while 2D partial dependence analysis establishes quantitative optimization ranges. This ML approach provides an efficient predictive tool for gas-liquid stirred bioreactor design and optimization.
基金supported by the National Key Research and Development Program of China (Nos.2018YFE0105600 and 2020YFC1806803)the New Zealand MBIE Catalyst Fund (No.92846082).
文摘Woodchip bioreactors are an eco-friendly technology for removing nitrogen(N)pollution.However,there needs to be more clarity regarding the dissolved organicmatter(DOM)characteristics and bacterial community succession mechanisms and their association with the N removal performance of bioreactors.The laboratory woodchip bioreactors were continuously operated for 360 days under three influent N level treatments,and the results showed that the average removal rate of TN was 45.80 g N/(m^(3)·day)when the influent N level was 100 mg N/L,which was better than 10 mg N/L and 50 mg N/L.Dynamic succession of bacterial communities in response to influent N levels and DOM characteristics was an important driver of TN removal rates.Medium to high N levels enriched a copiotroph bacterial module(Module 1)detected by network analysis,including Phenylobacterium,Xanthobacteraceae,Burkholderiaceae,Pseudomonas,and Magnetospirillaceae,carrying N-cycle related genes for denitrification and ammonia assimilation by the rapid consumption of DOM.Such a process can increase carbon limitation to stimulate local organic carbon decomposition to enrich oligotrophswith fewer N-cycle potentials(Module 2).Together,this study reveals that the compositional change ofDOMand bacterial community succession are closely related to N removal performance,providing an ecological basis for developing techniques for N-rich effluent treatment.
基金supported by Tianjin Municipal Science and Technology Bureau of China(Nos.20JCZDJC00380 and 18PTZWHZ00140).
文摘A biochar-assisted anaerobic membrane bioreactor(BC-AnMBR)was conducted to evaluate the performance in treating swine wastewater with different organic loading rates(OLR)ranging from 0.38 to 1.13 kg-COD/(m3.d).Results indicated that adding spent coffee grounds biochar(SCG-BC)improved the organic removal efficiency compared to the conventional AnMBR,with an overall COD removal rate of>95.01%.Meanwhile,methane production of up to 0.22 LCH4/gCOD with an improvement of 45.45%was achieved under a high OLR of 1.13 kg-COD/(m3.d).Furthermore,the transmembrane pressure(TMP)in the BC-AnMBR system was stable at 4.5 kPa,and no irreversible membrane fouling occurred within 125 days.Microbial community analysis revealed that the addition of SCG-BC increased the relative abundance of autotrophic methanogenic archaea,particularly Methanosarcina(from 0.11%to 11.16%)and Methanothrix(from 16.34%to 24.05%).More importantly,Desulfobacterota and Firmicutes phylum with direct interspecific electron transfer(DIET)capabilities were also enriched with autotrophic methanogens.Analysis of the electron transfer pathway showed that the concentration of c-type cytochromes increased by 38.60%in the presence of SCGBC,and thus facilitated the establishment of DIET and maintained high activity of the elec-tron transfer system even at high OLR.In short,the BC-AnMBR system performs well under various OLR conditions and is stable in the recovery energy system for swine wastewater.
文摘A new type of membrane bioreactor named 'airliftmembrane-bioreactor' is discussed. For municipal wastewaterreclamation, the preliminary study on airlift membrane-bioreactorshows its good performance such as higher flux and lower energyconsumption. The airlift membrane-bioreactor is potentiallyapplicable in bioengineer- ing and environmental protection fields.
基金Supported by the Ministry of Science and Technology of China!(No.96- 92 0 - 0 9- 0 4 )
文摘Experiments on treatment of domestic wastewater by membrane bioreactors were carried out.The results showed that this process could produce good quality effluent with low COD,turbidity and total count of bacteria.With intermittent operation and continuous aeration,the membrane flux was kept steady.The mechanisms of removing COD through membrane,the structure of membrane and filtration resistance were also discussed.
基金Supported by Zhejiang Provincial Natural Science Foundation of China(LY13C010002)Zhejiang Provincial Design and Research Institute of Environmental Science(2013F50005)~~
文摘We aimed to investigate the composition and phylogenetic rela-tionships of the viable but non-culturable （VBNC） state bacteria in pharmaceutical wastewater. [Method] Soil filter was used for constructing bioreactor. Based on the resuscitation- and growth-promoting function of Resuscitation Promoting Factor （Rpf） for VBNC bacteria, VBNC bacteria were isolated by most probable number （MPN） method and dilution-plating method and 16S rRNA gene phylogenetic analysis was carried out. [Result] In MPN culture system, Rpf could promote the resuscitation and growth of some bacteria. There were VBNC advantage floras that sensitive to Rpf in pharmaceutical wastewater. The culturable VBNC bacteria in pharmaceutical wastewater consisted of high-GC gram-positive actinomycetes including genera Mi-crobacterium, Gordonia and Leucobacter, and gram-negative bacteria including gen-era Candidimonas, Xanthobacter and Aminobacter. Four strains （ZYM1, ZYM3, ZYZR4, ZYXR1） could be potential novel species. [Conclusion] This research re-vealed there were VBNC bacteria in pharmaceutical wastewater. These results could provide important ideas and methods for further studies on VBNC bacteria in the pharmaceutical wastewater, especial y the formation mechanism and recovery mech-anism of VBNC bacteria and the advanced degradation process improvement of pharmaceutical wastewater.
基金supported by HuPao Dyeing Plant,JiangSu Province,China
文摘The performance of combined Fenton oxidation and membrane bioreactor （MBR） process for the advanced treatment of an effluent from an integrated dyeing wastewater treatment plant was evaluated. The experimental results revealed that under the optimum Fenton oxidation conditions （initial pH 5, H 2 O 2 dosage 17 mmol/L, and Fe^ 2＋ 1.7 mmol/L） the average total organic carbon （TOC） and color removal ratios were 39.3% and 69.5% after 35 min of reaction, respectively. Results from Zahn-Wallens Test also represented that Fenton process was effective to enhance the biodegradability of the test wastewater. As for the further purification of MBR process, TOC removal capacity was examined at different hydraulic retention times （HRT） of 10, 18 and 25 hr. Under the optimum HRT of 18 hr, the average TOC concentration and color of the final MBR effluent were 16.8 mg/L and 2 dilution time, respectively. The sludge yield coefficient was 0.13 g MLSS/g TOC and TOC degradation rate was 0.078 kg TOC/（m ^3 ·day）. The final effluent of MBR can meet the reuse criteria of urban recycling water – water quality standard for miscellaneous water consumption GBT18920-2002.
基金supported by the National Natural Science Foundation of China (Nos.51778522,and 51508450)the Program for Innovative Research Team in Shaanxi (No.IRT2013KCT-13)
文摘The effects of powdered activated carbon(PAC) addition on sludge morphological, aggregative and microbial properties in a dynamic membrane bioreactor(DMBR) were investigated to explore the enhancement mechanism of pollutants removal and filtration performance. Sludge properties were analyzed through various analytical measurements. The results showed that the improved sludge aggregation ability and the evolution of microbial communities affected sludge morphology in PAC-DMBR, as evidenced by the formation of large, regularly shaped and strengthened sludge flocs. The modifications of sludge characteristics promoted the formation process and filtration flux of the dynamic membrane(DM) layer. Additionally, PAC addition did not exert very significant influence on the propagation of eukaryotes(protists and metazoans)and microbial metabolic activity. High-throughput pyrosequencing results indicated that adding PAC improved the bacterial diversity in activated sludge, as PAC addition brought about additional microenvironment in the form of biological PAC(BPAC), which promoted the enrichment of Acinetobacter(13.9%), Comamonas(2.9%), Flavobacterium(0.31%) and Pseudomonas(0.62%), all contributing to sludge flocs formation and several(such as Acinetobacter) capable of biodegrading relatively complex organics. Therefore, PAC addition could favorably modify sludge properties from various aspects and thus enhance the DMBR performance.
文摘The anaerobic ammonia oxidation(Anammox) bioreactor was successfully started up with the nitrifying activated sludge. After anaerobically operated for 105 d, the bioreactor reached a good performance with removal percentage of both ammonia and nitrite higher than 95% and volumetric total nitrogen removal as high as 149.55 mmol/(L·d). The soft padding made an important contribution to the high efficiency and stability because it held a large amount of biomass in the bioreactor.
基金TheNationalNaturalScienceFoundationofChina (No .5 980 80 12 )andZhejiangProvince (No .5 9912 7)
文摘Population development of key groups of anaerobic and aerobic bacteria involved in municipal refuse decomposition under laboratory landfill bioreactors with and without leachate recycle and inoculation was measured since modeling municipal refuse was landfilled in bioreactors for about 210 days. Hydrolytic fermentative bacteria (HFB), hydrogen-producing acetogenic bacteria (HPAB), methane-producing bacteria (MPB), sulfate-reducing bacteria (SRB), anaerobic and aerobic cellulolytic bacteria and denitrabacteria were enumerated by the most probable number technique. The results showed that the dominant microorganism groups were the methanogenic bacteria including hydrolytic fermentative, hydrogen-producing acetogenic and methane-producing bacteria. They were present in fresh refuse but at low values and positively affected by leachate recycle and refuse inoculation. The amounts of HFB or HPAB in digesters D4 and D5 operated with inoculation and leachate recycle reached their maximum values of 1010 - 1012 cells/g dry refuse for HFB or 105 - 106 cells/g dry refuse for HPAB on day 60, in digester D3 operated with leachate recycle on day 120 for HFB (109 cells/g dry refuse) or on day 90 for HPAB (105 cells/g dry refuse), and in digesters D1 and D2 on day 210 for HFB (109 cells/g dry refuse) or on day 90 for HPAB (104 - 106 cells/g dry refuse). The population of methane-producing bacteria in digesters D4 and D5 sharply increased on days 60 and 90 respectively, however in digesters D1, D2 and D3 on day 120. Leachate recycle and inoculation changed the cellulolytic microorganisms composition of refuse ecosystem, the higher amounts of anaerobic cellulolytic bacteria were measured in digesters D4 and D5 (107 cells/g dry refuse), followed by digesters D3 (106 cells/g dry refuse), D2 or D1 (104 cells/g dry refuse). However, the amounts of aerobic cellulolytic bacteria were much lower than that of anaerobic cellulolytic bacteria. And it was higher in digesters D3 than those in digesters D1, D2, D4 and D5. The amounts of SRB and denitrabacteria were also higher in digester D5 than those in digesters D1, D2, D3 and D4. Refuse decomposition could be accelerated by leachate recycle and inoculation in the view of microorganism development.
基金supported by the National Natural Science Foundation of China (No 50678170)
文摘Three identical membrane bioreactors （MBRs） were operated over 2 years at different sludge retention time （SRT） of 10 d, 40 d and no sludge withdrawal （NS）, to elucidate and quantify the effect of SRT on the sludge characteristics and membrane fouling. The hydraulic retention times of these MBRs were controlled at 12 h. With increasing SRT, the sludge concentrations in the MBRs increased, whereas the ratio of volatile suspended solid to the total solid decreased, and the size of sludge granule diminished in the meantime. A higher sludge concentration at long SRT could maintain a better organic removal efficiency, and a longer SRT was propitious to the growth of nitrifiers. The performance of these MBRs for the removal of COD and NH4^＋-N did not change much with different SRTs. However, the bioactivity decreased as SRT increase. The measurement of specific oxygen uptake rates （SOUR） and fluorescence in situ hybridization （FISH） with rRNA-targeted oligonucleotide probes testified that SOUR and the proportion of the bacteria-specific probe EUB338 in all DAPI-stainable bacteria decreased with increasing SRT. The concentrations of total organic carbon, protein, polysaccharides and soluble extracellular polymeric substance （EPS） in the mixed liquor supernatant also decreased with increasing SRT. The membrane fouling rate was higher at shorter SRT, and the highest fouling rate appeared at a SRT of 10 d. Both the sludge cake layer and gel layer had contribution to the fouling resistance, but the relative contribution of the gel layer decreased as SRT increase.
