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Performance of a Mixed Inoculum of Sludge and Pit Mud for Short-And Medium-Chain Fatty Acids Production: Insight into key Microbiome and Functional Potential in Anaerobic Fermentation Inoculum

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SSRN 2023年

作者： Yu, Peng Wu, Menghan Bao, Wanyiin Wang, Hui State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing100084 China

In this study, medium-chain fatty acids (MCFA) production from food waste with ethanol as electron donor using three different inoculants (active sludge, pit mud and mixture of sludge and pit mud). The results show that the R3 (mixed inoculum of sludge and pit mud) produced 8539.1 mg COD/L of MCFA, which is significantly higher than that produced by R1 (active sludge, 2712.6 mg COD/L) and R2 (pit mud, 3585.9 mg COD/L). The major MCFAs were caproate and heptanoate, and the SCFA and MCFA selectivity reaches 59.2%. Microbial community analysis revealed that the relative abundance levels of Clostridium_sensu_stricto_1, Clostridium_sensu_stricto_12 and Oscibacter were positively correlated with MCFA production. Further analysis of the enzymes related genes involved in the MCFA biosynthesis indicates that they were mainly related to enzymes of Clostridium, Oscibacter and Ruminiclostridium. These were the key genera involved in the chain elongation process. Metagenomic analysis revealed that fatty acid biosynthesis (FAB) pathway was the main pathway of MCFA synthesis in all three fermentation reactors. The abundance levels of all FAB pathway related-genes and MCFA functional microorganism were higher in R3. Additionally, the enrichment of the main gene abundance of metabolic pathway revealing that the mixed inoculum of sludge and pit mud combined the ability of fatty acid biosynthesis and carbohydrate metabolism, with higher fermentation potential. Overall, this study provides new strategies and insights for MCFA production. © 2023, The Authors. All rights reserved.

关键词： Genes

Atmospheric environment monitoring technology and equipment in China:A review and outlook

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Journal of environmental Sciences 2023年第1期123卷 41-53页

作者： Youwen Sun Ting Yang Huaqiao Gui Xin Li Weigang Wang Jun Duan Shushuai Mao Hao Yin Bin Zhou Jianlei Lang Haijin Zhou Cheng Liu Pinhua Xie Key Laboratory of Environmental Optics and Technology Anhui Institute of Optics and Fine MechanicsHFIPSChinese Academy of SciencesHefei 230031China Department of Precision Machinery and Precision Instrumentation University of Science and Technology of ChinaHefei 230026China State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China State Key Laboratory for Structural Chemistry of Unstable and Stable Species Institute of ChemistryChinese Academy of SciencesBeijing 100190China Key Laboratory of Beijing on Regional Air Pollution Control College of Environmental&Energy EngineeringBeijing University of TechnologyBeijing 100124China Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP3) Department of Environmental Science and EngineeringFudan UniversityShanghai 200438China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China Key Laboratory of Precision Scientific Instrumentation of Anhui Higher Education Institutes University of Science and Technology of ChinaHefei 230026China Anhui Province Key Laboratory of Polar Environment and Global Change University of Science and Technology of ChinaHefei 230026China

Accurate monitoring of the atmospheric environment and its evolution are important for understanding the sources,chemical mechanisms,and transport processes of air pollution and carbon emissions in China,and for regulatory and control *** study gives an overview of atmospheric environment monitoring technology and equipment in China and summarizes the major achievements obtained in recent *** has made great progress in the development of atmospheric environment monitoring technology and equipment with decades of *** manufacturing level of atmospheric environment monitoring equipment and the quality of products have steadily improved,and a technical&production system that can meet the requirements of routine monitoring activities has been *** is expected that domestic atmospheric environment monitoring technology and equipment will be able to meet future demands for routine monitoring activities in China and provide scientific assistance for addressing air pollution problems.

关键词： Atmospheric pollution Atmospheric environment Atmospheric monitoring environmental instrument

Enhancement of Medium-Chain Fatty Acids Production from Sludge Anaerobic Fermentation Liquid Under Moderate Sulfate Reduction

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SSRN 2023年

作者： Gao, Shan Chen, Zhan Zhu, Shihui Yu, Jinlan Wen, Xianghua State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing100084 China

In this study, batch tests for chain elongation (CE) process of sludge anaerobic fermentation liquid (SAFL) under different SCOD/SO42- ratios were performed. The effects of sulfate reduction on the performance of medium-chain fatty acids (MCFAs) production, fermentation liquid properties and microbial communities were systematically investigated. The moderate sulfate reduction under the optimum SCOD/SO42- of 20:1 enhanced the n-caproate production, giving the maximum n-caproate concentration, selectivity and production rate of 5.49 g COD/L, 21.4% and 4.87 g COD/L/d, respectively. The excessive sulfate reduction under SCOD/SO42- ≤ 5 completely inhibited the CE process, resulting in almost no n-caproate generation. The variations in n-caproate production under different conditions of SCOD/SO42- were all well fitted with the modified Gompertz kinetic model. Alcaligenes and Ruminococcaceae_UCG-014 were the dominant genus-level biomarkers under moderate sulfate reduction (SCOD/SO42- = 20), which enhanced the n-caproate production by increasing the generation of acetyl-CoA and the hydrolysis of difficult biodegradable substances in SAFL. The findings in this work provide a strategy and a theoretical basis for the further enhancement of MCFAs production from excess sludge. © 2023, The Authors. All rights reserved.

关键词： Sulfur compounds

One-step ball milling-prepared nano Fe2O3 and nitrogendoped graphene with high oxygen reduction activity and its application in microbial fuel cells

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Frontiers of environmental Science & Engineering 2020年第2期14卷 185-195页

作者： Xingguo Guo Qiuying Wang Ting Xu Kajia Wei Mengxi Yin Peng Liang Xia Huang Xiaoyuan Zhang State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China

Developing high activity,low-cost and long durability catalysts for oxygen reduction reaction is of great significance for the practical application of microbial fuel *** ftill exposure of active sites in catalysts can enhance catalytic activity ***,novel Fe-N-doped graphene is successftilly synthesized via a one-step in situ ball milling *** graphite,ball milling graphene,N-doped graphene and Fe-N-doped graphene are applied in air cathodes,and enhanced performance is observed in microbial fuel cells with graphene-based ***,Fe-Ndoped graphene achieves the highest oxygen reduction reaction activity,with a maximum power density of 1380±20 mW/m^2 in microbial fUel cells and a current density of 23.8 A/m^2 at-0.16 V in electrochemical tests,which are comparable to commercial Pt and 390%and 640%of those of pristine *** investigation of the material characteristics reveals that the superior performance of Fe-Ndoped graphene results from the full exposure of Fe2O3 nanoparticles,pyrrolic N,pyridinic N and excellent Fe-N-G active sites on the graphene *** work not only suggests the strategy of maximally exposing active sites to optimize the potential of catalysts but also provides promising catalysts for the use of microbial fuel cells in sustainable energy generation.

关键词： Microbial fuel cells Air cathodes Nano Fe2O3 and nitrogen-doped graphene Oxygen reduction reaction

Nitrogen Removal Characteristics of a Novel Bacterium Klebsiella Sp. Tsh15 by Assimilatory/Dissimilatory Nitrate Reduction and Ammonia Assimilation

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SSRN 2023年

作者： Ren, Jilong Liu, Yanchen Huang, Xia State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing100084 China

A novel HNAD strain with excellent nitrogen metabolic ability was screened and identified as Klebsiella sp. TSH15 by 16S rRNA. The results demonstrated that the ammonia-N and nitrate-N removal rates were 2.99 mg/L/h and 2.53 mg/L/h under optimal conditions, respectively. The analysis of the whole genome indicated that strain TSH15 contained the key genes involved in assimilatory/dissimilatory nitrate reduction and ammonia assimilation, including nas, nar, nir, nor, glnA, gltB, gdhA, and amt. The relative expression levels of key nitrogen removal genes were further detected by RT-qPCR. The results indicated that the N metabolic pathways of strain TSH15 were the conversion of nitrate or nitrite to ammonia by assimilatory/dissimilatory nitrate reduction (NO3−→NO2−→NH4+) and further conversion of ammonia to glutamate (NH4+-N → Glutamate) by ammonia assimilation. These results indicated that the strain TSH15 had the potential to be applied to practical sewage treatment in the future. © 2023, The Authors. All rights reserved.

关键词： Nitrogen removal

Potential Stimulation of Nitrifying Bacteria by Landfill Leachate

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SSRN 2023年

作者： Li, Siqi Yang, Shaolin Xue, Yu Sahidul, M.D. Islam Liu, Yanchen Huang, Xia State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing100084 China

With the increasing complexity of influent composition in wastewater treatment plants, the potential stimulating effects of refractory organic matter in wastewater on growth characteristics and species shift of nitrifying bacteria need to be further investigated. In this study, municipal wastewater was co-treated with landfill leachate in the lab-scale reactor, and the competition and co-existence of Ca. Nitrotoga and Nitrospira were observed. The results demonstrated that the addition of landfill leachate can significantly promote the growth of Ca. Nitrotoga, whereas Ca. Nitrotoga populations remain less competitive in domestic wastewater operation. In addition, we found that the refractory organic matter in the landfill leachate had a potential stimulating effect on the maximum specific growth rate of Nitrosomonas (μmax, aob). The μmax, aob of Nitrosomonas in the control group was estimated to be 0.49 d-1 by fitting the ASM model, and the μmax, aob reached 0.66-0.71 d-1 after injection of refractory organic matter in the landfill leachate, while the maximum specific growth rate of NOB (μmax, nob) was always in the range of 1.05-1.13 d-1. These findings have positive significance for the understanding of potential stimuli in nitrification processes and the stable operation of innovative wastewater treatment process. © 2023, The Authors. All rights reserved.

关键词： Biogeochemistry

Aerobic granular sludge formation based on substrate availability:Effects of flow pattern and fermentation pretreatment

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Frontiers of environmental Science & Engineering 2020年第3期14卷 155-164页

作者： Quan Yuan Hui Gong Hao Xi Kaijun Wang State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China

The influences of flow patterns(mixed-flow and plug-flow)and fermentation pretreatment on aerobic granular sludge(AGS)formation with various substrate availability levels were investigated by running four identical laboratory-scale sequencing batch reactors(R1-R4),comparing two anaerobic feeding strategies and three kinds of substrates.R1 achieved faster granulation with a fast influent fill step followed by a modified anaerobic mixed-flow phase,but the AGS showed poorer stability with a cracked structure and a high suspended solids concentration in the *** anaerobic plug-flow feeding mode(with influent fed slowly from the bottom)in R2 provided deeper penetration depth for the substance to reach the core of A G S and accordingly strengthen A G S *** acidogenic upflow sludge bed reactor was introduced as a pretreatment to improve the AGS performance by enhancing glucose pre-fermentation(R4).AGS fed with mixed volatile fatty acids(VFA)after glucose fermentation showed similar performance compared with the reactor fed with acetate in the aspects of stability,structure,size distribution and nitrogen removal efficiency,and 74%similarity in the microbial *** actual wastewater with low VFA concentrations,fermentation treatment was suggested as a promising pretreatment for stable AGS granulation and operation.

关键词： Anaerobic plug-flow feeding mode Anaerobic mixed-flow mode Fermentation pretreatment Substrate gradient Penetration depth

Examining the Construction of China's Zero Waste Cities

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SSRN 2023年

作者： Li, Yushuang Li, Jinhui State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing100084 China

In the nationwide effort to address environmental issues caused by solid waste, more than 100 cities in China have been included in the list of national Zero Waste City (ZWC) construction projects. However, the absence of a standardized evaluation method hinders quantitative comparisons among these cities. To overcome this challenge, a comprehensive five-dimension evaluation method was developed, taking into account both the national indicators and city-specific construction indicator systems. After the construction indicator system was transformed to an evaluation one, data processing and weight assignment methods were applied to obtain evaluation results for each dimension using linear weighted synthesis. Subsequently, By combining the results from individual dimensions, an overall evaluation score was derived. Meanwhile, utilizing obstacle analysis models and weighted scores, critical areas requiring attention in ZWC construction could be identified. Empirical research was conducted on Shenzhen following this evaluation framework. The results revealed several key findings: 1) The quantitative score of ZWC performance in Shenzhen increased significantly from 58.9 to 108.3 after the implementation of the pilot project. 2) The dimensions of Management Measure, Support Capacity, and City Characteristic had achieved or approached full scores, indicating commendable progress. However, the Management Level dimension still had room for improvement. 3) While industrial waste management reached an excellent level and agricultural waste proved manageable, challenges persisted in domestic waste landfill and construction waste disposal. These aspects are considered weak points that may require longer-term efforts to address due to inherent objective conditions. © 2023, The Authors. All rights reserved.

关键词： Data handling

Photodegradation of soluble microbial products(SMPs) from membrane bioreactor by GO-COOH/TiO2/Ag

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Journal of environmental Sciences 2020年第2期32卷 292-300页

作者： Shuyan Yu Xia Huang State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China

This study aimed to explore a new degradation method-photocatalysis technology to polish membrane bioreactor(MBR) effluent, using 2,6-di-tert-butylphenol(2,6-DTBP) as a model soluble microbial product(SMP).2,6-DTBP is one of the predominant SMPs in MBR effluent, which is refractory and difficult to *** study developed a novel carboxylated graphene oxide/titanium dioxide/silver(GO-COOH/TiO2/Ag) nanocomposite to photodegrade 2,***-COOH/TiO2/Ag was successfully synthesized, using L-cysteine as the linker bonding TiO2/Ag to *** structural, morphological and optical properties of the GO-COOH/TiO2/Ag nanocomposite were characterized using various *** to synergistic effects, the GO-COOH/TiO2/Ag nanocomposite exhibited enhanced photocatalytic degradation performance under solar light irradiation when compared to TiO2, Ag and *** remove 25 mg/L 2,6-DTBP, the reaction time for GOCOOH/TiO2/Ag was only 30 min, faster than the 90 min required for pure TiO2 or *** addition, the 200 mg/L GO-COOH/TiO2/Ag nanocomposite aqueous solution showed the best performance under solar light, with 99% removal of 2,*** enhanced capability is likely due to the surface plasmon resonance(SPR) effect contributed by Ag nanoparticles(NPs) doped onto the *** addition, GO-COOH had a high effective surface area, which assisted in degrading the 2,6-DTBP through improved *** stability study showed that the photocatalytic activity of the GO-COOH/TiO2/Ag was stable enough for recycling multiple *** effective degradation performance and excellent stability demonstrates that the GO-COOH/TiO2/Ag nanocomposite can be a promising photocatalyst in the field of effluent SMP photodegradation, which solves the problem of the difficult biodegradation of highly toxic 2,6-DTBP.

关键词： Soluble microbial products (SMPs) 2,6-Di-tert-butylphenol (2,6-DTBP) Carboxylated graphene oxide/titanium dioxide/silver (GO-COOH/TiO2/Ag) nanocomposite Photocatalysis technology