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关键词： Ralstonia eutropha   Cupriavidus necator   Isopropanol   Carbon dioxide   Hydrogen   Bioreactor design   Gas fermentation   Autotrophy   Pressure  

摘要： A bioreactor was designed to provide high gas mass transfer to reach cell and product titres in the g L-1 level from CO2 for realistic, laboratory scale, engineered autotrophic strain evaluation. The design was based on independent CO2, H-2 and air inputs and the ability to operate at high pressures. The bioreactor configuration and cultivation strategy enabled growth of Cupriavidus necator strains for long periods, to reach over 3 g L-1 dry cell weight. No negative impact of the high pressure was observed on viability of the strains up to more than 4 bar overpressure. The cultivation was then carried out using an engineered isopropanol producing strain;in this case, 3.5 g L-1 isopropanol was obtained from CO2 as the sole carbon source. This is the first reported demonstration of a successful production from engineered bacteria of product in the g L-1 range on CO2 , raising the prospect of future development of CO2-based bioprocesses.

关键词： Agro-industrial wastewater   Filtration   Dynamic membrane   Capillary suction time   Membrane bioreactors  

摘要： Two bench-scale Self-Forming Dynamic Membrane BioReactors (SFD MBR), equipped with 50 mu m nylon meshes were set up and operated under aerobic conditions in order to treat canning and winery wastewaters. The results showed different behaviors of the two systems, confirming the strong dependence of SFD MBR performance on the type of biomass and, in turn, on the type of stream being treated. Both plants achieved good results in terms of effluent quality, demonstrating the suitability of the proposed technology. Median values of effluent turbidity were 2.7 and 15.4 NTU (Nephelometric Turbidity Units) in the reactors fed with canning wastewater and winery wastewater, respectively. The removal of organic matter (as COD, Chemical Oxygen Demand) was consistently above 90 %, although the retention of suspended solids was variable and somewhat dependent on operating conditions and feed composition. The activated sludge characteristics were observed to affect filtration performance and in particular the capillary suction time (CST) was a possible indicator of efficiency, with a threshold value of 11 s above which filtration performance decreased. This parameter is proposed as an early warning tool for changes in the filtration performance of an SFD MBR, both for effluent quality and cleaning requirements.

关键词： MBMBR   UV-photocatalytic-modified membrane   Membrane fouling   photocatalytic  

摘要： Membrane fouling is a major bottleneck in the application of moving bed-membrane bioreactors. A novel moving bed-UV-photocatalytic-modified membrane bioreactor (MB-UVPMBR) was proposed for efficient wastewater treatment and membrane fouling mitigation. Herein, the modified membrane served as photocatalysis and membrane processes simultaneously. Compared with the conventional moving bed-membrane bioreactor (MBMBR) and MB-UVPMBR without UV light irradiation, the MB-UVPMBR exhibited good effluent quality and anti-fouling ability with UV light irradiation. The cake layer resistance was reduced by 83%, and the pore blockage resistance was reduced by 88%, thus reducing the total membrane filtration resistance. The hydrophilicity of the modified membrane helped mitigate foulant deposition and cake layer formation on the membrane surface. The modified membrane effectively reduced the contents of soluble microbial products and foulants deposited on the membrane surface by photocatalysis. Additionally, the fouled membrane could be effectively regenerated by self-cleaning. (c) 2020 Elsevier Ltd. All rights reserved.

关键词： IFBBR   Nitrification-denitrification   16S rRNA   Low biomass yield   Energy consumption  

摘要： The performance of a lab-scale integrated anoxic and aerobic inverse fluidized bed bioreactors (IFBBR) for biological nutrient removal from synthetic municipal wastewater was studied at chemical oxygen demand (COD) loading rates of 0.34-2.10 kg COD/(m(3)-d) and nitrogen loading rates of 0.035-0213 kg N/(m(3)-d). Total COD removal efficiencies of >84% were achieved, concomitantly with complete nitrification. The overall nitrogen removal efficiencies were >75%. Low biomass yields of 0.030-0.101 g VSS/g COD were achieved. Compared with other IBBR systems, the energy consumption for this IFBBR system was an average 59% less at organic loading rates (OLRs) of 1.02 and 2.10 kg COD/(m(3)-d). Bacterial community structures of attached and suspended biomass revealed that the dominant phyla were Proleobacteria, Bacteroidetes, and Epsilonbacteraeota, etc. The relative abundance of ammonia-oxidizing bacteria (AOBs) and nitrite-oxidizing bacteria (NOBs) in the aerobic attached biomass were 0.451% and 0.110%, respectively. COD mass balance in the anoxic zone was closed by consideration of sulfate reduction, which was confirmed by the presence of genus Chlorobium (sulfate-reducing bacteria) in the anoxic attached biofilm with a relative abundance of 0.32%. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Diffusive Gradients in Thin-Films (DGT)   Nitrate   Denitrifying bioreactor   Removal rate   Grab sampling  

摘要： The increase in environmental nutrient availability as a result of human activities has necessitated the development of mitigation strategies for nutrient removal, such as nitrate. Current methods for determining the efficiency of different mitigation strategies required measurement of changes in nitrate concentrations, however, these methods can be expensive or do not account fully for the temporal variability of nitrate concentration. This study evaluated the utility of Diffusive Gradients in Thins-Films (DGT) for determining nitrate removal in two denitrifying bioreactors, and compared DGT performance to traditional approaches for determining performance, including high and low frequency water grab sampling. The binding layer was produced using the Purolite (R) A520E anion exchange resin. The uptake and elution efficiencies were 98.8% and 93.4% respectively. DGTs of three material diffusion layer thicknesses were placed in piezometers along longitudinal transects, to enable calculation of the diffusive boundary layer and provide replicates. These were removed after 16, 24 and 36 h, and the accumulated nitrate masses were extracted and quantified to calculate nitrate concentration. Concentrations were subsequently utilised to calculate nitrate removal rates in both bioreactors. Grab samples were taken at 30 and 60 min intervals over those periods, nitrate concentrations were also measured to determine nitrate removal. DGTs provided nitrate removal rates at bioreactor site one (controlled flow, wastewater treatment) of 14.83-30.75 g N m(-3) d(-1), and 1.22-3.63 g N m(-3) d(-1) at site two (variable flow, agricultural run-off). DGT determined nitrate concentrations and removal rates were in strong accordance with high frequency grab sampling, but data collection via DGTs was considerably easier. Utilising DGTs for the measurement of bioreactor performance overcame many of the challenges associated with high frequency grab sampling, and other methods, such as account

关键词： Biomass gasification wastewater   Biological treatment   Packed bed bioreactor   Rhodococcus opacus   Biochar   Bio-support material  

摘要： Wastewater from biomass gasification chiefly contains monocyclic (MAHs) and polycyclic aromatic hydrocarbons (PAHs) that are generated by wet scrubbing process of raw synthetic gas during its cleaning process. These MAHs and PAHs are well-known as toxic, mutagenic, and carcinogenic agents which need to be removed prior to their release into the environment. The present study evaluated the potential of an up-flow packed bed bioreactor (UFPBBR) with immobilized Rhodococcus opacus onto biochar loaded polyurethane foam (PUF) as the packing material for treating biomass gasification wastewater (BGWW). Initially, the bioreactor was operated utilizing only PUF as the support material and a maximum COD removal of 81 +/- 2.65% was achieved with 1820 mg L-1 of influent COD concentration and 24 h of HRT. Using biochar loaded PUF as the support material;more than 95 +/- 1.27% of COD removal was attained under the same COD loading condition and HRT. Furthermore, the wastewater was detoxified to 96.2% demonstrating the ability of UFPBBR system using the novel biochar based bio-support material for biomass gasification wastewater treatment. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Multi-objective optimization   evolutionary algorithms   bone tissue engineering   3D scaffold   labor cost  

摘要： Tissue engineering is a fast progressing domain where solutions are provided for organ failure or tissue damage. In this domain, computer models can facilitate the design of optimal production process conditions leading to robust and economically viable products. In this study, we use a previously published computationally efficient model, describing the neotissue growth (cells + their extracellular matrix) inside 3D scaffolds in a perfusion bioreactor. In order to find the most cost-effective medium refreshment strategy for the bioreactor culture, a multi-objective optimization strategy was developed aimed at maximizing the neotissue growth while minimizing the total cost of the experiment. Four evolutionary optimization algorithms (NSGAII, MOPSO, MOEA/D and GDEIII) were applied to the problem and the Pareto frontier was computed in all methods. All algorithms led to a similar outcome, albeit with different convergence speeds. The simulation results indicated that, given the actual cost of the labor compared to the medium cost, the most cost-efficient way of refreshing the medium was obtained by minimizing the refreshment frequency and maximizing the refreshment amount.

关键词： Partial desalination   Biomineralization   Bacillus subtilis   Seawater   Calcium   Magnesium  

摘要： The use of non-desalinated seawater for mining purposes is not recommendable because of the high salinity and the presence of some ions, that is, Ca2+ and Mg2+, that can hamper the mineral tailings separation process besides being responsible for scaling formation in pipelines and equipment. To remove these ions from seawater, a novel treatment involving a biomineralization process was tested using a fluidized bed bioreactor (FBB) filled with immobilized beads of the halotolerant ureolytic strain Bacillus subtilis LN8B. The FBB was operated in batch mode according to a sequence of six cycles of eight days. The highest efficiency in removing Ca2+ and Mg2+ occurred in the first cycle for both ions, achieving the removal rate of similar to 100% by day four for Ca2+ and similar to 80% by day six for Mg2+, respectively. Precipitates from FBB were mainly composed of similar to 70.2% of hydromagnesite, and similar to 17.8% of aragonite. Furthermore, the efficiency of biologically pretreated seawater (BSw) was evaluated as mineral tailings sedimentation medium and compared with three types of water: (i) tap water (Tw);(ii) seawater (Sw);and (iii) distilled water, (Dw). The results showed that the settling velocity in BSw was the highest (i.e., 6.23 +/- 0.48 m h(-1)).

关键词： Polyurethane   Continuous flow   Removal   Toxicity   Chlorpyrifos   Diazinon  

摘要： In this study, we evaluated polyurethane foam (PF), volcanic rock (VR), and a modified plastic cap (MPC) as supports for the immobilization of organophosphorus (OP) pesticide-degrading actinobacterial strains. The colonization and activity of four streptomycetes were favoured by PF, which was selected as the carrier to use in a continuous stirred tank bioreactor (CSTR) that can be operated at increasing inflows of a pesticide mixture that contains the insecticides chlorpyrifos (CP) and diazinon (DZ). Our results demonstrate that the CSTR can be operated at flow rates of 10 and 40 mL h(-1) with greater than 85% removal of the pesticides in the short term. A significant decrease in the efficiency of CP removal was observed at the highest inflows into the reactor. The CP and DZ loading rates in the bioreactor ranged from 0.44 to 1.68 mg L-1 h(-1) and from 0.50 to 2.17 mg L-1 h(-1), respectively. Although the treated wastewater exhibited moderate toxicity for Raphanus sativus, a bioreactor inoculated with a mixed culture formed by Streptomyces spp. strains AC5, AC9, GA11 and ISP13 may provide an effective biotechnological strategy for the reduction of OP pesticide residues produced during agronomic and manufacturing practices and therefore prevent environmental pesticidal pollution.