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关键词： Wastewater treatment plant   Sludge volume index   Total nitrogen   Simulation and control   Neural networks  

摘要： A mathematical model to simulate and study the interaction between the content of nitrogen compounds in the outflow of a wastewater treatment plant and the efficiency of activated sludge sedimentation in its secondary clarifiers is presented in this paper. The goal of the model is to control the biological reactor settings (e.g. total nitrogen (TN) and sedimentation properties of the sludge) in case of discontinuity of quality indicators at wastewater inflow. Such an approach has not been applied so far. Continuity of calculated numerical values of model-dependent variables (TN, sludge volume index) was obtained by replacing the independent variables with the results of calculations obtained using the statistical models. Data mining methods were used to simulate the content of nitrogen compounds at the wastewater outlet. To simulate active sludge sedimentation a classification model based on the logistic regression method was used. According to the obtained results the proposed comprehensive model of simulation, referring to TN and activated sludge sedimentation, enables optimal selection of bioreactor settings.

关键词： metagenome-assembled genomes   metatranscriptomics   sulfate reduction   syntrophic butyrate oxidation   methanogenesis   metagenomics  

摘要： The anaerobic digestion of wastes is globally important in the production of methane (CH4) as a biofuel. When sulfate is present, sulfate-reducing bacteria (SRB) are stimulated, competing with methanogens for common substrates, which decreases CH4 production and results in the formation of corrosive, odorous hydrogen sulfide gas (H2S). Here, we show that a population of SRB within a methanogenic bioreactor fed only butyrate for years immediately (within hours) responded to sulfate availability and shifted the microbial community dynamics within the bioreactor. By mapping shotgun metatranscriptomes to metagenome-assembled genomes, we shed light on the transcriptomic responses of key community members in response to increased sulfate provision. We link these short-term transcriptional responses to long-term niche partitioning using comparative metagenomic analyses. Our results suggest that sulfate provision supports a syntrophic butyrate oxidation community that disfavors poly-beta-hydroxyalkanoate storage and that hydrogenotrophic SRB populations effectively exclude obligately hydrogenotrophic, but not aceticlastic, methanogens when sulfate is readily available. These findings elucidate key ecological dynamics between SRB, methanogens and syntrophic butyrate-oxidizing bacteria, which can be applied to a variety of engineered and natural systems.

关键词： Granular activated carbon   Nitrate-dependent anaerobic methane oxidation   Membrane bioreactor   Process properties   Mechanism  

摘要： Eutrophication and global warming are two main urgent environmental problems around the world. Nitrate-dependent Anaerobic Methane Oxidation (NdAMO) is a bioprocess coupling nitrate reduction with anaerobic methane oxidation, which could mitigate of these two environmental issues simultaneously. In this study, a newly granular active carbon-NdAMO-membrane bioreactor (GAC-NdAMO-MBR) system was established to evaluate its nitrogen removal efficiency, membrane fouling property and the probable strengthening mechanism was also uncovered. Results indicated that the nitrate removal rate in GAC-NdAMO-MBR reached 31.85 +/- 3.19 mgN.L-1.d(-1) while it was only 10.35 +/- 2.02 mgN.L-1.d(-1) in NdAMO-MBR system (lack of GAC), which was multiplied three-fold. The membrane flux decay rate of GAC- NdAMO -MBR was 0.15 L/m(2).h.d while it was 0.49 L/m(2).h.d without GAC, and the addition of GAC could extend membrane fouling time for 2.5 times. Notablely, the relative abundance of NdAMO bacteria sharply increased from 27.15% to 56.91% after GAC addition while the NdAMO archaea showed similar variation trend. The physicochemical property of GAC mainly contributed the strengthening effect. The porous structure of GAC absorbed methane and adhered by microorganism, which enhance microorganism amount and metabolic activity. The mechanical strength of GAC scoured membrane surface to mitigate external fouling and pores absorbed EPS to reduce internal fouling. The combined effects could improve NdAMO microorganism growth and metabolism activity and finally improved nitrogen removal performance and controlled membrane fouling. These findings could deep the knowledge of NdAMO process and help extend its application potential in environment science and engineering.

摘要： 306

关键词： Bioreactor   Denitrification   NO3-   Nuclear industrial wastewater  

摘要： In this work, a down-flow fixed bed anaerobic biofilm reactor filled by biological ceramsites were prepared to remove the high concentration of NO3- (> 20 g/L) from nuclear industry wastewaters. The effects of hydraulic retention time, the concentration of NO3-, the molar ratio of C/N and temperature on the removal efficiencies of NO3- were investigated. The results showed that the removal rate of NO3- with the initial concentration of 6 g/L can reach 99% or more by controlling the hydraulic retention time at 0.75 h, the molar ratio of C/N at 1.5 and the temperature over 18 degrees C. In the process, the NO2- was not accumulated, and the autotrophic denitrifying bacteria grow well in anaerobic biofilm reactors, proving a usable method for removing the high concentration NO3- from nuclear industrial wastewaters.

关键词： Reverse membrane bioreactor   Wheat straw hydrolysate   Diffusion rate   Fermentation   Inhibitor detoxification  

摘要： Optimal production of lignocellulosic bioethanol is hindered due to commonly faced issues with the presence of inhibitory compounds and sequentially consumed sugars in the lignocellulosic hydrolysate. Therefore, in order to find a robust fermentation approach, this study aimed at enhancing simultaneous co-assimilation of sugars, and inhibitor tolerance and detoxification. Therefore, fermentation of toxic wheat straw hydrolysate containing up to 20 g/l furfural, using the concentration-driven diffusion-based technique of reverse membrane bioreactor (rMBR) was studied. The rMBR fermentation of the hydrolysate led to complete furfural detoxification and the conversion of 87 % of sugars into ethanol at a yield of 0.48 g/g. Moreover, when the toxicity level of the hydrolysate was increased to 9 g/l of initial furfural, the system responded exceptionally by reducing 89 % of the inhibitor while only experiencing about 25 % drop in the ethanol yield. In addition, using this diffusion-based set-up in extremely inhibitory conditions (16 g/l furfural), cells could detoxify 40 % of the furfural at a high initial furfural to cell ratio of 9.5:1. The rMBR set-up applied proved that by properly synchronizing the medium condition, membrane area, and inhibitor to cell ratio, some of the shortcomings with conventional lignocellulosic fermentation can be tackled, guaranteeing a robust fermentation.

关键词： Petrochemical wastewaters   Anaerobic bioconversion   Model fitting   Dewatering  

摘要： Petrochemical wastewaters treatment represents a serious challenge due to the high toxicity and complex chemical components. In this study, the biodegradability, mineralization behaviors and methane productivity of eight different types of petrochemical wastewaters were evaluated in series of semi-continuous bioreactors. Methane production strongly depended on the characteristics of wastewaters and chemical constituents. The highest methane yield of 305.9 +/- 2.7 mL/g-COD was achieved by purified terephthalic acid wastewater, followed by ethylene glycol, polyester, etc. Comparatively, one-step-SCN- wastewater produced the lowest methane yield (4.7 +/- 0.7 mL/g-COD) owing to high toxicity and low biodegradability. Modified Gompertz model confirmed that purified terephthalic acid, ethylene glycol and polyester wastewaters had a short lag-phase of 1.2, 1.7 and 0.2 days, respectively. Nonetheless, the formation of by-products such as proteins, polysaccharides and ammonia nitrogen throughout anaerobic digestion reflected the high activity of anaerobic microorganisms, confirming the technical feasibility of anaerobic biotechnology in treating petrochemical wastewaters.

摘要： 436

关键词： Aerobic microbiological processes   Biological water treatment   Fluidized beds   Hybrid bioreactors  

摘要： A hybrid fluidized-bed bioreactor for water purification was proposed and analyzed. It is a novel type of bioreactor characterized by hitherto unknown stationary and dynamic features. Steady-state characteristics of this hybrid bioreactor with external liquid circulation are presented. A quantitative analysis of steady-state properties of the bioreactor was performed with the aid of an original mathematical model developed for a double-substrate aerobic microbiological process. A steady-state analysis of aerobic processes characterized by different oxygen demand was performed. The effect of essential parameters was evaluated, including carbonaceous substrate concentration in the feed stream to the apparatus, aeration intensity, total residence time of a liquid in the bioreactor, and height of the bed of fine carrier particles.

关键词： ISRU   Bioreactor   Iron   Space exploration   Biomining   Algae  

摘要： Transporting materials from Earth to Mars is a significant logistical constraint on mission design. Thus, a sustained settlement will be enhanced if it can perform elemental extraction and utilization in situ. In this study, all requirements to test a novel, biological approach for in situ resource utilization (ISRU) are conceptualized. We present designs for two bioreactor systems to be incorporated in a Mars habitat. The first system is a standard algae bioreactor which produces oxygen and biomass. The second bioreactor is capable of taking in Martian regolith and extracting enhanced iron ores from it via biological processes. Additionally, we propose the use of the leftover iron-poor but biomass rich material in a plant compartment. The multiple, different compartments feed into each other, creating an interconnected process enhancing self-sufficiency. In this paper, computational fluid dynamics of mixing behavior under reduced gravity, a breakdown of the process flow for a biological ISRU approach and exploratory in silico evaluation of the feasibility are presented.