Article
Chemistry, Multidisciplinary
Weiwei Wu, Linghui Xie, Jian Li Hao
Summary: This study investigated the feasibility of providing a trading platform for construction and demolition (C&D) waste management and resource recovery in China. By comparing the time delay of traditional transaction process and platform transaction process, the superior efficiency of the platform was revealed. The findings of this study contribute to improving the efficiency of C&D waste management and resource recovery.
SUSTAINABLE CHEMISTRY AND PHARMACY
(2022)
Article
Engineering, Environmental
Kok Siew Ng, Anh N. Phan
Summary: This study introduces a novel concept of integrating material recovery with waste-to-hydrogen production, aiming to save disposal costs and increase revenue by utilizing rejected materials through a Gasification-H-2 system. It is recommended to use a larger scale Gasification-H-2 system to compete with the production cost of hydrogen from fossil-based systems.
RESOURCES CONSERVATION AND RECYCLING
(2021)
Article
Engineering, Environmental
V. R. Vaishna, Jiffin Sam, Rothish R. Nair, M. K. Akhina, K. Haritha, K. P. Prathish
Summary: The present study demonstrates an innovative circular economic process using agricultural waste (nutmeg fruit rind) to create an effective adsorbent, which can remove hexavalent chromium ions from contaminated streams. The study highlights the potential of nutmeg fruit rind waste as an affordable and eco-friendly solution for wastewater treatment. The adsorption mechanism involves electrostatic interaction, hydrogen bonding, ion exchange, and surface complexation. The spent adsorbent can be subjected to anaerobic digestion to recover biogas and chromium, contributing to resource recovery and mitigating contamination risks.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2023)
Article
Green & Sustainable Science & Technology
Estefani Rondon Toro, Amaya Lobo, Antonio Gallardo Izquierdo
Summary: Circular Economy is crucial for sustainability, and waste processing plants play a key role in minimizing resource loss. This study proposes a new circularity indicator for municipal solid waste treatment plants, which evaluates material and energy recovery efficiency.
JOURNAL OF CLEANER PRODUCTION
(2022)
Article
Engineering, Environmental
Ramesh Kumar, Chengjia Liu, Geon-Soo Ha, Kwang Ho Kim, Sankha Chakrabortty, Suraj K. Tripathy, Young -Kwon Park, Moonis Ali Khan, Krishna Kumar Yadav, Marina M. S. . Cabral-Pinto, Byong-Hun Jeon
Summary: An experimental investigation successfully recovered and recycled 96.5% of molybdenum from industrial wastewater using a novel membrane-integrated hybrid technology. The wastewater volume was reduced by 94%, and molybdenum concentration was increased from 1.32 g/L to 10.2 g/L. The molybdenum was efficiently recovered as ammonium molybdate and further converted into high-purity MoO3 through chemical precipitation and thermal decomposition.
RESOURCES CONSERVATION AND RECYCLING
(2023)
Article
Engineering, Environmental
Samuela Guida, Giorgia Rubertelli, Bruce Jefferson, Ana Soares
Summary: The study demonstrates that HAIX technology is capable of effectively removing and recovering PO4-P from municipal wastewater. By efficiently managing the regenerant and adding calcium hydroxide, both regeneration effectiveness and effluent quality can be significantly improved.
CHEMICAL ENGINEERING JOURNAL
(2021)
Review
Engineering, Environmental
Ramesh Kumar, Sankha Chakrabortty, Prasenjit Chakrabortty, Jayato Nayak, Chengjia Liu, Moonis Ali Khan, Geon-Soo Ha, Kwang Ho Kim, Moon Son, Hyun-Seog Roh, Suraj K. Tripathy, Byong-Hun Jeon
Summary: Lithium-ion batteries (LiBs) are crucial for the transition towards a renewable and low-carbon society, replacing fossil fuel-based power sources. The increasing adoption of electric vehicles will lead to a high demand for LiBs and challenges in metal supply. Urban mining can be used to sustainably manage and recycle spent LiBs. Current recycling rates are low, and a paradigm shift is needed. A membrane-integrated hybrid approach can enhance the recovery of valuable metals from spent LiBs and contribute to a circular economy.
CHEMICAL ENGINEERING JOURNAL
(2023)
Review
Green & Sustainable Science & Technology
Arezoo Dadrasnia, Isabella de Bona Munoz, Eduardo Hernandez Yanez, Imane Uald Lamkaddam, Mabel Mora, Sergio Ponsa, Mansour Ahmed, Laia Llenas Argelaguet, Paul M. Williams, Darren L. Oatley-Radcliffe
Summary: Livestock expansion and mass production of manure have led to an excess of nutrients in many areas, calling for the efficient recovery and re-use of nutrients from waste. Freeze concentration technology shows promise with high concentration factor and low energy usage, but remains semi-industrialized and faces challenges in nutrient recovery and energy consumption.
JOURNAL OF CLEANER PRODUCTION
(2021)
Article
Energy & Fuels
Zelda Z. Rasmeni, Daniel M. Madyira, Antony. Matheri
Summary: Beer is widely consumed globally and the brewing industry contributes significantly to the economy. However, the production of beer results in a large amount of organic waste, which poses environmental challenges and costs for waste management. This study explores the use of brewery spent yeast for energy production and evaluates its potential as biomass for energy resource recovery, aiming to shift the brewing sector towards a circular economy practice.
Article
Green & Sustainable Science & Technology
Daniel Holzer, Romana Rauter, Eva Fleiss, Tobias Stern
Summary: Research indicates that there is limited empirical evidence on key corporate practices in small and medium-sized enterprises (SMEs) crucial for transitioning towards a circular economy (CE), as well as a lack of knowledge on the definition of CE for SMEs. Efficient resource utilization, resource procurement, and cooperation with stakeholders are identified as major areas of importance for Austrian SMEs in the context of CE.
JOURNAL OF CLEANER PRODUCTION
(2021)
Article
Nanoscience & Nanotechnology
Brandon Clark, Genesis Gilles, William A. Tarpeh
Summary: This study demonstrates the use of zinc-acrylate ligand exchange resin and tertiary amine acrylic weak base resin to achieve resin-mediated pH control, improving the selectivity and adsorption efficiency of recovering total ammonia nitrogen (TAN) from wastewater.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Environmental Sciences
Hadad Elroi, Grzymala Zbigniew, Wojcik-Czerniawska Agnieszka, Szewczyk Piotr
Summary: This study explores optimizing waste resource efficiency through the Circular Economy (CE) framework. Through a comprehensive review and case analysis, we find that the principles of circular economy are crucial in extending product lifecycles and reducing waste, and propose strategies to optimize waste management.
FRONTIERS IN ENVIRONMENTAL SCIENCE
(2023)
Article
Green & Sustainable Science & Technology
Karolina Jaderko-Skubis, Mariusz Kruczek, Magdalena Pichlak
Summary: Every year, a significant amount of waste is produced by the industrial sector. This study analyzes the quantitative and qualitative aspects of industrial waste streams, and visually represents their flow. The research identifies potential waste flows and sectors that can implement industrial symbiosis. The example of Silesia demonstrates the potential of this model and its potential implementation in other locations.
Article
Agricultural Engineering
Veronica Diaz, Juan Carlos Leyva-Diaz, Mari Carmen Almecija, Jose Manuel Poyatos, Maria del Mar Munio, Jaime Martin-Pascual
Summary: Microalgae-based technologies can be used for bioremediation of wastewater, converting it into valuable biomass and energy products while effectively removing nutrients. Microalgae can also extract lipids for biodiesel production, making it a sustainable source of bioenergy.
BIORESOURCE TECHNOLOGY
(2022)
Article
Engineering, Environmental
Sabolc Pap, Huiyi Zhang, Aleksandra Bogdan, Derek T. Elsby, Stuart W. Gibb, Barbara Bremner, Mark A. Taggart
Summary: This study introduces a novel pilot-scale technology (FILTRAFLO(TM)-P reactor) for the recovery of phosphate from wastewater in a rural setting. The results demonstrate that the FILTRAFLO(TM)-P unit can efficiently remove phosphate from effluent, even at low concentrations, and has the potential for resource recovery through bio-based waste management. The adsorption mechanisms of phosphate were identified as surface microprecipitation and inner-sphere complexation.
Editorial Material
Engineering, Environmental
Zhiguo Yuan, Eberhard Morgenroth
Article
Engineering, Environmental
Mengxiong Wu, Chun -Yu Lai, Yulu Wang, Zhiguo Yuan, Jianhua Guo
Summary: Nitrate contamination is a common problem in water environments and poses health risks. This study investigates the feasibility of using propane and butane as electron donors for nitrate reduction. The results showed that propane and butane could continuously remove nitrate under oxygen-limiting conditions, and certain microorganisms were responsible for the oxidation of these gases and the reduction of nitrate.
Article
Biochemical Research Methods
Xiaoqiong Qi, Karl Bertling, Mitchell S. Stark, Thomas Taimre, Yung-Ching Kao, Yah Leng Lim, She Han, Blake O'Brien, Angus Collins, Michael Walsh, Jari Torniainen, Timothy Gillespie, Bogdan C. Donose, Paul Dean, Lian He Li, Edmund H. Linfield, A. Giles Davies, Dragan Indjin, H. Peter Soyer, Aleksandar D. Rakic
Summary: In this study, a terahertz (THz) imaging technology based on a narrow band quantum cascade laser (QCL) at 2.8 THz was used for early detection of skin pathologies. THz imaging of unstained human skin samples showed good correlation with traditional histopathologic stained images. The THz contrast mechanisms in dehydrated samples were also analyzed. This study suggests that THz imaging could be a feasible modality for non-visible skin cancer detection.
BIOMEDICAL OPTICS EXPRESS
(2023)
Article
Engineering, Environmental
Mengying Xie, Yue Zheng, Xueqin Zhang, Jun Xia, Nova Maulani, Zhiguo Yuan, Chen Cai, Shihu Hu
Summary: A study found that a member of the archaeal family Methanoperedenaceae, known as Candidatus 'Methanoperedens nitroreducens', can use formate as an alternative electron donor. Experimental results showed that this archaeon can oxidize formate and reduce nitrate in the absence or presence of methane. The genes involved in formate metabolism were identified in the genome of Ca. 'M. nitroreducens', and their expression levels increased when formate was consumed.
ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS
(2023)
Article
Engineering, Environmental
Jiuling Li, Nur Nabilah Naina Mohamad, Keshab Sharma, Zhiguo Yuan
Summary: Establishing efficient boundary conditions is crucial for modeling heat transfer in sewers and recovering heat from wastewater. This study presents a novel approach using Fourier transform and data-driven models to determine the thickness of the soil layer and predict temperatures at the soil-layer boundary. The methodology improves the accuracy and speed of sewer heat transfer modeling.
Review
Engineering, Environmental
Liang Zhang, Yan-Ying Qiu, Keshab R. Sharma, Tao Shi, Yarong Song, Jianliang Sun, Zhensheng Liang, Zhiguo Yuan, Feng Jiang
Summary: This article provides a comprehensive review of sulfide control measures, including chemical additives, ventilation, and pipe material improvements, to prevent sewer corrosion and odor emission caused by sulfate-reducing bacteria. It emphasizes the importance of managing sewer networks as an integral part of an urban water system.
Article
Engineering, Environmental
Zhetai Hu, Tao Liu, Zicheng Su, Jing Zhao, Jianhua Guo, Shihu Hu, Zhiguo Yuan, Min Zheng
Summary: Acidic partial nitritation (PN) is a stable method for wastewater treatment that can achieve nitrite accumulation and ammonium reduction. However, directly applying anaerobic ammonium oxidation (anammox) to treat acid PN effluent is problematic. This study demonstrated the adaptation of anammox to acidic pH in a moving bed biofilm reactor (MBBR), achieving high nitrogen removal efficiency. The presence of biofilm plays a critical role in protecting anammox bacteria in acidic environments.
Article
Engineering, Environmental
Tao Liu, Shihu Hu, Zhiguo Yuan, Jianhua Guo
Summary: This study developed a novel technology using a granule-based sequencing batch reactor (GSBR) to achieve simultaneous removal of dissolved methane and nitrogen. The GSBR demonstrated high-level removal rates and efficiencies for nitrogen and dissolved methane during long-term demonstration. The availability of different electron acceptors significantly affected the removal of ammonium and dissolved methane, as well as the microbial communities and functional genes. These findings expand the applications of novel n-DAMO microorganisms and provide insights into microbial cooperation and competition in granular systems.
Article
Engineering, Environmental
Yanchen Liu, Zhiqiang Zuo, He Li, Yaxin Xing, Dong Cheng, Miao Guo, Tao Liu, Min Zheng, Zhiguo Yuan, Xia Huang
Summary: This study proposes a new approach for effective sulfide control in urban sewers. It involves the advanced oxidation of ferrous sulfide in sewer sediment to produce hydroxyl radicals, which can simultaneously oxidize sulfide and reduce microbial sulfate-reducing activity. Experimental results demonstrate that this method can substantially reduce sulfide concentration and save chemical use.
Article
Multidisciplinary Sciences
Zhetai Hu, Lanqing Li, Xiaotong Cen, Min Zheng, Shihu Hu, Xiuheng Wang, Yarong Song, Kangning Xu, Zhiguo Yuan
Summary: Integrated urban water management is an effective approach for managing urban water resources, which utilizes integrated technological solutions to achieve system-wide benefits. Research has shown that the process of producing iron salts can improve wastewater treatment in urban water systems and simultaneously recover high-quality bioenergy.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Xueqin Zhang, Georgina H. Joyce, Andy O. Leu, Jing Zhao, Hesamoddin Rabiee, Bernardino Virdis, Gene W. Tyson, Zhiguo Yuan, Simon J. Mcilroy, Shihu Hu
Summary: Anaerobic methanotrophic archaea (ANME) use multi-heme c-type cytochromes (MHCs) to mediate the reduction of metals and electrodes. Experimental evidence supports the involvement of these cytochromes in extracellular electron transfer (EET) from ANME to different electron sinks.
NATURE COMMUNICATIONS
(2023)
Article
Energy & Fuels
Jibing Qi, Yuliang Li, Youzhi Liu, Tong Yang, Yandong Liu, Zhiguo Yuan, Jianjun Yi
Summary: In this study, the Henry's law constant of volatiles in polymer systems was investigated by measuring the gas phase equilibrium partial pressure. The results show that the gas phase equilibrium partial pressure and Henry's law constant of volatiles increase with the increase of temperature and polymer viscosity.
CHINA PETROLEUM PROCESSING & PETROCHEMICAL TECHNOLOGY
(2023)
Article
Environmental Sciences
Haoran Duan, Min Zheng, Jiyun Li, Tao Liu, Zhiyao Wang, Sohan Shrestha, Bingzheng Wang, Liu Ye, Shihu Hu, Zhiguo Yuan
Summary: This study investigates the impact of high hydraulic loading rates on partial nitritation and proposes operational strategies to facilitate mainstream partial nitritation and anaerobic ammonium oxidation process.
Article
Engineering, Environmental
Xiaotong Cen, Haoran Duan, Zhetai Hu, Xin Huang, Jiaying Li, Zhiguo Yuan, Min Zheng
Summary: The study shows that dosing magnesium hydroxide in sewer systems has various benefits on downstream treatment processes, including increasing sewage pH, reducing sulfide and methane concentrations, and increasing alkalinity and volatile fatty acids concentration in sewer effluent. Dosing magnesium hydroxide can also improve ammonium oxidation and NOx reduction rates in cases with limited alkalinity and carbon sources availability, without detrimental effects on anaerobic sludge digesters. Furthermore, the use of magnesium hydroxide dosing can potentially reduce downstream chemical demand and costs for carbon sources, pH adjustment, and sludge dewatering.
Article
Engineering, Environmental
Kefeng Zhang, Veljko Prodanovic, Hengke Zhao, Min Zheng, Shihu Hu, Pei-Ying Hong, Zhiguo Yuan, Ana Deletic
Summary: This study investigated the performance of vegetated biofiltration systems (VBS) in treating nitrogen-rich wastewater. The results showed that VBS was able to effectively treat nitrogen through traditional denitrification and the anaerobic ammonium oxidation (anammox) process. The type of carbon source and retention time had significant impacts on nitrogen removal, while dissolved oxygen levels did not. Microbial analysis revealed differences between different carbon sources and the presence of a suspected anammox genus in the system.
ENVIRONMENTAL SCIENCE-WATER RESEARCH & TECHNOLOGY
(2023)
Article
Engineering, Environmental
Rong-Gui Zhu, Chang-Gui Pan, Feng-Jiao Peng, Chao-Yang Zhou, Jun-Jie Hu, Kefu Yu
Summary: This comprehensive survey investigated the occurrence, bioaccumulation, and trophic magnification of parabens and their metabolite 4-HB in a marine food web. Results showed that parabens were the predominant pollutants in marine organisms, with significant bioaccumulation from sediments. The estimated trophic magnification factor indicated biomagnification for MeP and trophic dilution for 4-HB. Overall, the risks for humans consuming marine organisms were found to be low.
Article
Engineering, Environmental
Andres F. Torres-Franco, Deborah Leroy-Freitas, Cristina Martinez-Fraile, Elisa Rodriguez, Pedro A. Garcia-Encina, Raul Munoz
Summary: Anaerobic and microalgae-based technologies have emerged as sustainable alternatives for municipal wastewater treatment. However, the presence of viruses in the treated wastewater is a major concern for reuse applications. This study assessed the ability of these technologies to reduce viruses during secondary wastewater treatment. The results showed that all technologies were effective in reducing the concentration of viruses, with microalgae-based treatment exhibiting the highest potential for reducing the disinfection requirements of treated wastewater.
Article
Engineering, Environmental
Young Gwang Kim, Sae Yun Kwon, Spencer J. Washburn, Scott C. Brooks, Ji Won Yoon, Lucien Besnard
Summary: The study uses Hg isotope ratios to identify the sources and exposure pathways of mercury in bivalves, finding that dissolved Hg phases in the water column are the primary source and exposure pathway to bivalves. This provides new insights into using bivalves as bioindicators for sediment quality monitoring.
Article
Engineering, Environmental
Hui Geng, Ying Xu, Rui Liu, Dianhai Yang, Xiaohu Dai
Summary: This study investigates the effect of cation exchange resin (CER) on the sequential recovery of hydrogen and methane from anaerobic digestion (AD) and the corresponding mechanisms. The results show that CER can simultaneously enhance the production of hydrogen and methane by promoting the solubilisation, hydrolysis, and acidification of organic matter. Additionally, CER facilitates effective contact between bacteria and organic particulates and reduces the energy barrier for mass transfer during methane production. The study also reveals changes in the microbial community structure and metagenomics during the AD process.
Article
Engineering, Environmental
Xiaojing Lin, Zhan Jin, Shunfeng Jiang, Zhiquan Wang, Suqing Wu, Ke Bei, Min Zhao, Xiangyong Zheng
Summary: Dehumidification combined with addition of absorbent resin supplement (ARS) was used to achieve rapid evaporation of non-pretreated urine, resulting in high water evaporation efficiency and nutrient recovery.
Article
Engineering, Environmental
Yangli Che, Chaoran Lin, Shen Li, Jiao Liu, Longhai Zhu, Shilei Yu, Nan Wang, Haoshuai Li, Mutai Bao, Yang Zhou, Tonghao Si, Rui Bao
Summary: Hydrodynamic processes play a crucial role in the transmission of sediments, microbial assembly, and organic carbon redistribution in the ocean. Through experiments and analysis, we found that hydrodynamics shape the assembly of microbial communities and control the redistribution of different sourced organic carbon, thereby influencing microbial-mediated biogeochemical transformation.
Article
Engineering, Environmental
Chao Chen, Yu Yang, Nigel J. D. Graham, Zhenyu Li, Xingtao Yang, Zhining Wang, Nadia Farhat, Johannes S. Vrouwenvelder, Li -an Hou
Summary: The fouling of seawater reverse osmosis membranes is a persistent challenge in desalination. This study monitored the operational performance of a desalination plant for 7 years and the fouling development in different areas of membrane modules. The findings showed that operational performance declined over time and fouling mainly occurred at the feed side of the modules, with the highest microbial diversity. Keystone species like Chloroflexi and Planctomycetes played an important role in maintaining community structure and biofilm maturation. Polysaccharides, soluble microbial products, marine humic acid-like substances, and inorganic substances contributed to fouling. Overall, biofouling had a significant impact on membrane fouling after 7 years of operation.
Article
Engineering, Environmental
Dan Li, Jieyi Sun, Yibo Fu, Wentao Hong, Heli Wang, Qian Yang, Junhong Wu, Sen Yang, Jianhui Xu, Yunfei Zhang, Yirong Deng, Yin Zhong, Ping'an Peng
Summary: Sulfidation-oxidation treatment of magnetite (Fe3O4) enhances the production of dark center dot OH, which can efficiently degrade dissolved organic matter (DOM) and accelerate carbon cycling.
Article
Engineering, Environmental
Cheng Yu, Kaijun Wang, Kaiyuan Zhang, Ruiyang Liu, Pingping Zheng
Summary: This study implemented a microaerobic-aerobic configuration in a full-scale municipal wastewater treatment facility and investigated the effects on sludge characteristics, pollutant removal, microbial community, and granulation mechanisms. The results showed successful transition from flocculent-activated sludge to well-defined AGS after two months of operation. The primary pathways for pollutant removal were simultaneous nitrification, denitrification, and phosphorus removal. Moreover, the incorporation of internal separators induced shifts in the flow pattern, which promoted granulation.
Article
Engineering, Environmental
Zhe Zhang, Shaoyang Hu, Guangrong Sun, Wei Wang
Summary: Halogenated aromatic disinfection byproducts (DBPs), such as halogenated phenols, have garnered widespread attention due to their high toxicity and prevalence. This study reports on the analysis, occurrence, and cytotoxicity of a group of emerging halogenated aromatic DBPs, known as halogenated polyhydroxyphenols (HPPs), in drinking water.
Article
Engineering, Environmental
Shengyue Chen, Jinliang Huang, Peng Wang, Xi Tang, Zhenyu Zhang
Summary: Accurate prediction of river water quality is crucial for sustainable water management. This study introduces wavelet analysis and transfer learning techniques to assist LSTM modeling, proposing a newly coupled modeling approach that improves short-term prediction of river water quality.
Article
Engineering, Environmental
Bang Du, Xinmin Zhan, Piet N. L. Lens, Yifeng Zhang, Guangxue Wu
Summary: Efficient anaerobic digestion relies on the cooperation of different microorganisms with different metabolic pathways. This study investigated the effects of different operational modes and the addition of powdered activated carbon (PAC) on ethanol metabolic pathways. The results showed that the SBR mode and the presence of CO2 facilitated ethanol metabolism towards propionate production, while the CFR mode with extended solids retention time enriched Geobacter. Adjusting operational modes and PAC addition can modulate anaerobic ethanol metabolism and enrich Geobacter.
Article
Engineering, Environmental
Wanfa Wang, Si-Liang Li, Jun Zhong, Yuanbi Yi, Fujun Yue, Zenglei Han, Qixin Wu, Ding He, Cong-Qiang Liu
Summary: This study compares the carbon biogeochemical processes in karst and non-karst regions within large thermal stratified river-reservoir systems. The results demonstrate that karst reservoirs have a reduced potential for carbon emissions and highlight the importance of considering geologic settings to improve accuracy in regional and global CO2 emission estimates.
Article
Engineering, Environmental
Chunxia Jiang, Zelong Zhao, Dong Zhu, Xiong Pan, Yuyi Yang
Summary: This study analyzed the occurrence and distribution of antibiotic resistance genes (ARGs) in different environmental media of the Yangtze River using metagenomics. Core resistome dominated by multidrug resistance genes was found in all samples, while rare resistome dominated by various resistance genes was more prevalent in plasmids. Specific bacteria were identified as hosts for both core and rare resistomes, with high clinical concern ARGs found in the rare resistome. Particle-associated environment provided the most ideal conditions for resistome hosts. This study provided insights into the genetic locations of ARGs and the community assembly mechanisms of ARG hosts in freshwater environments.
Article
Engineering, Environmental
Yu Zhang, Yongtao He, Linchun Jia, Lei Xu, Zheng Wang, Yueling He, Ling Xiong, Xumeng Lin, Hong Chen, Gang Xue
Summary: By synergizing organic carbon source, thiosulfate, and zero-valent iron, efficient mixotrophic denitrification of oligotrophic secondary effluent can be achieved. Thiosulfate plays a vital role in promoting TN removal efficiency, while corrosion of Fe0 releases OH- to neutralize H+ from thiosulfate-driven denitrification, creating a suitable environment for denitrification. The coordination of thiosulfate and Fe0 maintains the dominance of Thiobacillus for denitrification.