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关键词： Membrane bioreactor   Leachate treatment   Effect of prolonged SRT   Microbial community   Next-generation sequencing  

摘要： Leachate treatment is challenging owing to the complex composition of pollutants. This study investigated the treatment performance of a membrane bioreactor (MBR) and the microbial community structure corresponding to the effect of prolonged sludge retention times (SRTs) under restricted aeration. In the present study, a pilot-scale MBR was designed to treat leachate after being pretreated with an anaerobic filter for continuous operation for 240 days. The experimental results showed that removal performance of over 90% was achieved for biochemical oxygen demand, total Kjeldahl nitrogen, ammonia-nitrogen, and suspended solids when the MBR was operated at SRTs of 150-300 days. The results on microbial communities revealed that Proteobacteria, Bacteroidetes, Firmicutes, Planctomycetes, Chloroflexi, and Actinobacteria were the major phyla. Furthermore, ammonia-oxidizing bacteria belonging to Nitrosomonadaceae were considered to play a vital role in the ammonia-nitrogen removal. A high abundance of Rhizobiales was detected on the biofilm of the membrane, which could be the key driver of bio-fouling. The dynamic changes in the microbial community indicate steady performance of MBR and can act as an indicator of membrane bio-fouling. The results of our study highlight that MBR can be viably operated in long SRTs under restricted aeration for leachate treatment with technical, economic, and environmental feasibility for resource recovery.

关键词： Acinetobacter sp   Nitrogen removal   Nitrogen balance   Enhanced biological treatment  

摘要： A novel bacteria with heterotrophic nitrification and aerobic denitrification ability was obtained from a membrane bioreactor (MBR) and identified as Acinetobacter sp. TSH1. The nitrogen removal characteristics, nitrogen balance analysis, kinetic characteristics, and enhanced biological treatment in MBR of the novel isolated strain TSH1 were determined. Results showed that strain TSH1 could remove approximately 96.6% of NH4+-N, 82.9% of NO2--N and 98.7% of NO3- -N in 24 h, and the corresponding maximum removal rates were 3.64 mg-N/(L.h), 1.77 mg-N/(L.h) and 3.94 mg-N/(L.h). The nitrogen balance analysis indicated that most of NH4+-N (62.6%) and NO3- -N (71.9%) were transformed to gaseous nitrogen. The kinetic experiments showed that strain TSH1 had a high Km of 151.64 mg-NH4+-N/L and 203.25 mg-NO3--N/L. The enhanced biological treatment of synthetic wastewater in MBR showed that the strain TSH1 can significantly improve the nitrogen removal efficiency.

关键词： Anaerobic membrane bioreactor   Partial nitritation-anammox   Municipal wastewater treatment   Energy saving   Pilot-scale plant  

摘要： A novel municipal wastewater treatment process towards energy neutrality and reduced carbon emissions was established by combining a submerged anaerobic membrane bioreactor (SAnMBR) with a one-stage partial nitritation-anammox (PN/A), and was demonstrated at pilot-scale at 25 degrees C. The overall COD and BOD5 removal efficiencies were 95.1% and 96.4%, respectively, with 20.3 mg L-1 COD and 5.2 mg L-1 BOD5 remaining in the final effluent. The total nitrogen (TN) removal efficiency was 81.7%, resulting 7.3 mg L-1 TN was discharged from the system. The biogas yield was 0.222 NL g-1 COD removed with a methane content range of 78-81%. Approximately 90% of influent COD was removed in the SAnMBR, and 70% of influent nitrogen was removed in the PN/A. The denitrification which occurred in the PN/A enhanced overall COD and nitrogen removal. The successful operation of this pilot-scale plant indicates the SAnMBR-PN/A process is suitable for treating real municipal wastewater.

关键词： 3D printing   bioreactor   cardiovascular   decellularization   pericardium   porcine aorta  

摘要： Decellularization (DC) of biomaterials with bioreactors is widely used to produce scaffolds for tissue engineering. This study uses 3D printing to develop efficient but low-cost DC bioreactors. Two bioreactors were developed to decellularize pericardial patches and vascular grafts. Flow profiles and pressure distribution inside the bioreactors were optimized by steady-state computational fluid dynamics (CFD) analysis. Printing materials were evaluated by cytotoxicity assessment. Following evaluation, all parts of the bioreactors were 3D printed in a commercial fused deposition modeling printer. Samples of bovine pericardia and porcine aortae were decellularized using established protocols. An immersion and agitation setup was used as a control. With histological assessment, DNA quantification and biomechanical testing treatment effects were evaluated. CFD analysis of the pericardial bioreactor revealed even flow and pressure distribution in between all pericardia. The CFD analysis of the vessel bioreactor showed increased intraluminal flow rate and pressure compared to the vessel's outside. Cytotoxicity assessment of the used printing material revealed no adverse effect on the tissue. Complete DC was achieved for all samples using the 3D printed bioreactors while DAPI staining revealed residual cells in aortic vessels of the control group. Histological analysis showed no structural changes in the decellularized samples. Additionally, biomechanical properties exhibited no significant change compared to native samples. This study presents a novel approach to manufacturing highly efficient and low budget 3D printed bioreactors for the DC of biomaterials. When compared to standard protocols, the bioreactors offer a cost effective, fast, and reproducible approach, which vastly improves the DC results.

关键词： bioreactor   stirred suspension bioreactor   germ cell   spermatogonia   culture  

摘要： Male survivors of childhood cancer are at risk of suffering from infertility in adulthood because of gonadotoxic chemotherapies. For adult men, sperm collection and preservation are routine procedures prior to treatment;however, this is not an option for pre-pubertal children. From young boys, a small biopsy may be taken before chemotherapy, and spermatogonia may be propagated in vitro for future transplantation to restore fertility. A robust system that allows for scalable expansion of spermatogonia within a controlled environment is therefore required. Stirred suspension culture has been applied to different types of stem cells but has so far not been explored for spermatogonia. Here, we report that pre-pubertal porcine spermatogonia proliferate more in bioreactor suspension culture, compared with static culture. Interestingly, oxygen tension provides an avenue to modulate spermatogonia status, with culture under 10% oxygen retaining a more undifferentiated state and reducing proliferation in comparison with the conventional approach of culturing under ambient oxygen levels. Spermatogonia grown in bioreactors upregulate the Wnt/ beta-catenin pathway, which, along with enhanced gas and nutrient exchange observed in bioreactor culture, may synergistically account for higher spermatogonia proliferation. Therefore, stirred suspension bioreactors provide novel platforms to culture spermatogonia in a scalable manner and with minimal handling.

关键词： Biological desulfurization   Anoxic conditions   Nitrification   Nitrogen removal optimization   Biogas   Nitrate equivalent  

摘要： A preliminary assessment has been carried out on the integration of an anoxic biotrickling filter and a nitrification bioreactor for the simultaneous treatment of ammonium-rich water and H2S contained in a biogas stream. The nutrient consumption in the biotrickling filter was as follows (mol(-1) NO3--N): 6.3.10 4 +/- 1.2.10(-4) mol PO43- P, 0.04 +/- 0.05 mol NH4+-N and 0.04 +/- 0.03 mol K+-K. Furthermore, it was possible to supply a mixture of biogenic NO3 and NO2 into the biotrickling filter from the nitrification bioreactor to obtain a maximum elimination capacity of 152 gH(2)S-S m(-3) h(-1). The equivalence between the two compounds was 1 mol NO3--N equal to 1.6 mol NO2--N. The biotrickling filter was also operated under a stepped variable inlet load (30-100 gH(2)S-S m(-3) h(-1)) and outlet H2S concentrations of less than 150 ppm(V) were obtained. It was also possible to maintain the outlet H2S concentration close to 15 ppm(V) with a feedback controller by manipulating the feed flow (in the nitrification bioreactor). Two stepped variable inlet loads were tested (60-111 and 16-102 gH(2)S-S m(-3) h(-1)) under this type of control. The implementation of feedback control could enable the exploitation of biogas in a fuel cell, since the H2S concentrations were 15.1 +/- 4.3 and 15.0 +/- 3.4 ppm(V). Finally, the anoxic biotrickling filter experienced partial denitrification and this implied a loss of the desulfurization effectiveness related to SO42- production.

关键词： PHA production   F   M ratio   Carbon sources   DO concentration  

摘要： In the present study, the interactive effects of two numerical variables, viz. feed to biomass concentration (F/M) ratio and dissolved oxygen (DO) concentration, and a categorical variable (type of carbon sources) on polyhydroxyalkanoate (PHA) production by activated sludge generated from an airlift bioreactor were evaluated. Three different carbon sources including acetate, soft drink industrial wastewater, and Faraman industrial wastewater (industrial estate in Kermanshah, Iran) were used as single feed to accumulation bioreactor. The yield of PHA on substrate, specific PHA production rate, and specific substrate uptake rate were evaluated as responses. The maximum PHA content was obtained around 34.2, 4.8, and 11.3% (mg PHA/mg VSS) using acetate, soft drink industrial wastewater, and Faraman industrial wastewater as carbon sources, respectively, at the optimum condition with F/M ratio of 3.5 mg COD-S/mg VSS and a DO concentration of 2 mg/L. The PHA content was mainly poly (3-hydroxybutyrate) (PHB) when acetate and soft drink industrial wastewater were used as a solo carbon source, while Faraman industrial wastewater resulted in the production of copolymer P(3HB-co-3HV).

关键词： Pressmud   Municipal solid waste   DTLF-BRLF   Co-landfilling   Biomethane production  

摘要： In this study, anaerobic co-landfilling of municipal solid waste (MSW) and sugar mill pressmud (PM) was performed in four different proportions [PM:MSW] viz. 0:1 (control: BR1), 1:3 (BR2), 1:1 (BR3) and 3:1 (BR4). Efficacy assessment of Dry tomb - Bioreactor landfill (DTLF - BRLF) operation was carried out through leachate characterization and biomethane production. Leachate recirculation as a part of bioreactor operation after 194th day onwards showed promising degradation of co-wastes. Moreover, leachate decontamination and methane production were reliant on co-disposal proportions of PM and MSW. Maximum biomethane generation of 46.355L was obtained in landfill lysimeter BR3 followed by BR4 (34.680L), BR2 (24.275L) and BR1 (12.850L). Both logistic function and Gompertz growth models showed efficient fitting (R2 > 0.99) for observed methane production. This research could be a baseline study for selective operation of combined dry tomb and bioreactor landfilling at full scale in co-disposal scenarios.

关键词： Methanogen and nitrifying genes   Anaerobic digestion   Organic loading rate   Food waste  

摘要： This work was aimed to evaluate the distinctive food waste (FW) organic loading rates (OLR) on methanogen and nitrifying genes dynamics and its correlation with identified relative abundance of bacterial dynamics during the anaerobic digestion. This experiment were carried out in the digesters at high OLR of food wastes at (4 to 8 g volatile solids/liter/day reactor R1) and (6 to 10 g volatile solids/liter/day reactor R2). The results shown that the relative abundance of mcrA, mcrB and mcrG genes were richest in the first day of both R1 and R2. In addition, the most of nitrifying genes were greater in after 34 days digestion in R2, while these genes did not show the specific regularity in R1. Finally, the correlation figure shows that Clostridium and Lactobacillus genera were significantly correlated with the different organic acids and methanogen and nitrifying genes dynamics.

关键词： W/O emulsion   thermal stability   droplet digital PCR   lipophilic emulsifiers   critical micelle concentration  

摘要： Conventional polymerase chain reaction (PCR) performed in a continuous aqueous phase often shows an inability to detect ultra-low DNA concentration. Droplet digital PCR, where DNA polymerization happens in isolated water droplets of water-in-oil (W/O) emulsions, could significantly improve the detection limit. However, water droplet breakups under multiple thermal cycles necessary for DNA polymerization is preventing the wide-spread application of such technology. The present research aims to develop thermally stable coarse W/O emulsions that could act as DNA microreactors. Span 80, polyglycerol polyricinoleate (PGPR), or sodium bis(2-ethylhexyl) sulfosuccinate (AOT) were dissolved in mixtures of light and heavy mineral oils at different concentrations. The aqueous phase was selected based on PCR protocol, without the presence of enzymes and DNA. Emulsions prepared without bovine serum albumin (BSA) in the aqueous phase was used as a control to understand its effect on stability. Emulsions were formed using a vortex mixer for 2 minutes at 3200 rpm. Only the emulsions without visible aqueous phase separation were exposed to PCR thermal cycling. The volume mean diameters of water droplets were calculated by image analysis. Span 80-stabilized emulsions destabilized upon thermal cycling, while PGPR-stabilized emulsions remained stable with an increase in water droplet size. AOT was able to form thermally stable emulsions, with an average droplet size around 119 mu m without any significant change. The influence of emulsifiers concentration, surface saturation, molecular interaction with BSA at the interface, and continuous oil phase viscosity was considered to explain the mechanism of emulsion formation and thermal stability.