Article
Environmental Sciences
Adrian Gonzalez, Jules B. van Lier, Merle K. de Kreuk
Summary: The study highlights that the characteristics of waste activated sludge are influenced by the wastewater or growth media, leading to different degrees of recalcitrance in the produced sludge. By adjusting the growth medium, it is possible to obtain lab-grown sludge with a similar response to thermal pre-treatment, showing slowly-biodegradable properties.
JOURNAL OF ENVIRONMENTAL MANAGEMENT
(2021)
Article
Engineering, Environmental
B. van Veenhuyzen, S. Tichapondwa, C. Horstmann, E. Chirwa, H. G. Brink
Summary: Chemically activated waste activated sewage sludge showed potential for Pb(II) adsorption, with ZnCl2 activation significantly increasing adsorption capacity and surface area without changing the surface structure. However, HCl and H2SO4 activation ceased the adsorption process. Additionally, cationic exchange with hydrogen, calcium, and zinc was identified as a significant mechanism for Pb(II) removal.
JOURNAL OF HAZARDOUS MATERIALS
(2021)
Review
Microbiology
Jianyi Xu, Mengyao Sheng, Zhou Yang, Jiguo Qiu, Jun Zhang, Lei Zhang, Jian He
Summary: Strain HX-5-24(T) was isolated from sludge in Maanshan city, China, showing similarities with Lysobacter dokdonensis DS-58(T) but forming a distinct subclade. It is proposed as a novel species named Lysobacter gilvus.
ARCHIVES OF MICROBIOLOGY
(2021)
Article
Agricultural Engineering
Zhetai Hu, Weiwei Li, Haoran Duan, Xin Huang, Jia Meng, Liangzhen Yang, Min Zheng
Summary: This study proposed an integrated approach to efficiently recover phosphorus (P) as vivianite from waste activated sludge (WAS) and simultaneously enhance sludge dewaterability. Acidification and Fe3+ reduction were conducted to convert Fe and P from solid phase to liquid phase. Acid-elutriation technology was then introduced to enhance liquor-solid separation. Finally, vivianite was obtained via sludge eluate neutralization. The enhanced sludge dewaterability not only increases the recovery efficiency of Fe and P but also decreases the cost of sludge disposal.
BIORESOURCE TECHNOLOGY
(2023)
Article
Engineering, Environmental
J. Tauber, B. Flesch, V. Parravicini, K. Svardal, J. Krampe
Summary: This study examined operational data from three large Austrian wastewater treatment plants over a 2-year period. The research focused on the impact of salt peaks in influent on activated sludge parameters and activity. Results showed that increasing salt concentrations may lead to decreased settling velocities and adsorption rates of activated sludge.
WATER SCIENCE AND TECHNOLOGY
(2021)
Article
Environmental Sciences
Bianhe Lu, Jin Qian, Fei He, Peifang Wang, Yuxuan He, Sijing Tang, Xin Tian
Summary: This study investigated the impact of perfluorooctane sulfonate (PFOS) on the performance and microbial community of activated sludge. The results showed that the presence of PFOS reduced the removal efficiency of total nitrogen and improved the removal efficiency of total phosphorus, while also leading to the deterioration of activated sludge's dewatering performance.
ENVIRONMENTAL POLLUTION
(2022)
Article
Engineering, Environmental
Katarzyna Slipko, Roberto B. M. Marano, Eddie Cytryn, Valentina Merkus, Markus Wogerbauer, Jorg Krampe, Edouard Jurkevitch, Norbert Kreuzinger
Summary: This study demonstrates that the core sludge microbiome in CAS systems is resilient to sub-inhibitory concentrations of ciprofloxacin, showing no measurable effects on antibiotic resistance determinants at a functional, structural, and antibiotic resistance levels.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2021)
Article
Engineering, Environmental
Qingmiao Yu, Xianda Hu, Fuzheng Zhao, Chenyu Zhu, Linchang Guan, Hongqiang Ren, Jinju Geng
Summary: This study analyzed the effect of dissolved organic matter (DOM) composition on the removal efficiency of NGT in wastewater treatment plants (WWTPs). The results showed that DOM composition was a significant factor in NGT removal, and its effect was mediated by regulating core microbial communities.
Article
Plant Sciences
Alessandro Infantino, Alessandro Grottoli, Valentino Bergamaschi, Safa Oufensou, Lester W. Burgess, Virgilio Balmas
Summary: This paper presents FusaHelp, a computer-based tool for the morphological identification of common Fusarium species. Developed by experienced authors, FusaHelp aims to provide support for researchers working with this genus, helping them quickly identify the Fusarium species they are working with.
JOURNAL OF PLANT PATHOLOGY
(2023)
Article
Environmental Sciences
Ning Xie, Liping Zhong, Liao Ouyang, Wang Xu, Qinghuai Zeng, Keju Wang, Madiha Zaynab, Huirong Chen, Fangfang Xu, Shuangfei Li
Summary: Functional microorganisms in activated sludge play a crucial role in reducing environmental threats from municipal wastewater treatment plants. This study utilized Illumina NovaSeq sequencing to analyze microbial communities in different stages of two WWTP projects in Shenzhen, China. The results demonstrate the importance of nitrate, total nitrogen, COD, and nutrients in affecting bacterial community structure in AS.
Review
Environmental Sciences
Yankai Liang, Rui Wang, Wenquan Sun, Yongjun Sun
Summary: This article analyzes the composition and properties of municipal sludge and examines the factors affecting its dewatering performance. It introduces various chemical conditioning methods and systematically analyzes the principles and applications of existing sludge conditioning technologies. It emphasizes the importance of developing a more appropriate combination of sludge conditioning and dewatering processes and optimizing the dewatering process by developing new efficient and environmentally friendly sludge conditioning agents.
Article
Engineering, Environmental
Serena Lima, Alberto Brucato, Giuseppe Caputo, Franco Grisafi, Francesca Scargiali
Summary: In this study, municipal wastewater was treated using microalgal/activated sludge consortia to achieve a positive interaction between microalgae and heterotrophic bacteria for bioremediation. The strain of Chlorella sp CW2 was isolated and characterized, and its combination with activated sludge in different ratios was evaluated for wastewater treatment. The best results were obtained with a ratio of 1:2 and 2:1 for Chlorella sp CW2 and activated sludge, achieving COD, total nitrogen, and total phosphorous removal efficiencies of 81.39%, 86.12%, and 82.89% respectively. Analysis of the residual biomass suggested that the most promising sample for valorization was the combination of Chlorella sp CW2 and activated sludge in a ratio of 1:5.
JOURNAL OF WATER PROCESS ENGINEERING
(2022)
Article
Environmental Sciences
Jin Qian, Xixian He, Peifang Wang, Bin Xu, Kun Li, Bianhe Lu, Wen Jin, Sijing Tang
Summary: The study investigated the acute effects of three polystyrene nanoplastics on the extracellular polymeric substance composition of activated sludge. The results showed significant inhibition in EPS and protein production, as well as cellular oxidative stress and cell membrane damage. The influence on EPS and cytotoxicity of activated sludge varied with the surface functional groups of the polystyrene nanoplastics.
ENVIRONMENTAL POLLUTION
(2021)
Article
Agriculture, Dairy & Animal Science
Xiongbo He, Zhisen Luo, Chunxu Zhao, Liangliang Huang, Yunrong Yan, Bin Kang
Summary: This study maps the species composition and distribution of hairtail in Chinese seas, while also examining their growth, age, and trophic characteristics. Findings reveal that the largehead hairtail species has the highest stability and impact on trophic structure stability. Hairtail have consistently ranked first in single-species production in Chinese marine fishery. By sampling along China's coastal areas, the study identifies six species and highlights the significance of largehead hairtail and Savalai hairtail in catch production. The research underscores the importance of effective recovery and reasonable utilization of hairtail resources in Chinese marine fishery.
Article
Environmental Sciences
Jia Meng, Haoran Duan, Zhiguo Yuan, Min Zheng
Summary: This study found that sludge thickening can change the buffer capacity of sludge, which affects the efficiency and acid/base usage of sludge treatment.
SCIENCE OF THE TOTAL ENVIRONMENT
(2022)
Review
Microbiology
Hans-Curt Flemming, Eric D. van Hullebusch, Thomas R. Neu, Per H. Nielsen, Thomas Seviour, Paul Stoodley, Jost Wingender, Stefan Wuertz
Summary: In this review, the authors revisit the understanding of the biofilm matrix and discuss the diversity of its components and the novel aspects of their functional interactions. The biofilm matrix plays a crucial role in stabilizing microbial cells and fulfilling various functions. It is dynamic and influenced by physico-chemical and biological interactions as well as environmental conditions.
NATURE REVIEWS MICROBIOLOGY
(2023)
Article
Engineering, Environmental
Nerea Uri-Carreno, Per H. Nielsen, Krist V. Gernaey, Qian Wang, Ulla Gro Nielsen, Marta Nierychlo, Susan H. Hansen, Lisette Thomsen, Xavier Flores-Alsina
Summary: Membrane-Aerated Biofilm Reactors (MABRs) are an effective alternative for wastewater treatment plants (WWTP) with enhanced nitrogen removal capacity and reduced energy consumption. This study demonstrates the impact of oxidation-reduction potential (ORP) on the performance of MABRs, showing that low ORP conditions can hinder nitrification. By increasing ORP and replacing/cleaning membranes, nitrification rates and the abundance of nitrifying organisms were significantly improved. The study also suggests that low ORP conditions promote the reduction of iron and sulfur compounds, leading to deposition in the biofilm and inhibiting nitrifiers growth.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Ecology
Mantas Sereika, Francesca Petriglieri, Thomas Bygh Nymann Jensen, Artur Sannikov, Morten Hoppe, Per Halkjaer Nielsen, Ian P. G. Marshall, Andreas Schramm, Mads Albertsen
Summary: Cable bacteria are centimeter-long filamentous bacteria capable of long-distance electron transfer. They are currently classified into two candidate genera: Candidatus Electronema, found in freshwater, and Candidatus Electrothrix, found in saltwater. To address the lack of complete genomic information, researchers performed Nanopore long-read and Illumina short-read shotgun sequencing, resulting in the recovery of multiple cable bacteria genomes. Phylogenomic analysis classified two circular genomes as novel species: Ca. Electronema halotolerans and Ca. Electrothrix laxa. The discovery of Ca. Electronema halotolerans in brackish-water sediment suggests its evolutionary link between marine and freshwater cable bacteria lineages.
Article
Biochemical Research Methods
Tue Sparholt Jorgensen, Martin Schou Pedersen, Kai Blin, Franziska Kuntke, Henrik K. Salling, Rasmus L. Marvig, Thomas Y. Michaelsen, Mads Albertsen, Helene Larsen
Summary: SpikeSeq is a Sanger sequencing-based method for detecting Variants of Concern (VOC) and key mutations of the novel coronavirus. It is simple, cost-effective, and can be implemented in any diagnostic lab.
JOURNAL OF VIROLOGICAL METHODS
(2023)
Article
Engineering, Environmental
Morten Kam Dahl Dueholm, Maaike Besteman, Emil Juel Zeuner, Marie Riisgaard-Jensen, Morten Eneberg Nielsen, Sofie Zacho Vestergaard, Soren Heidelbach, Nicolai Sundgaard Bekker, Per Halkjaer Nielsen
Summary: A study investigated the genomic potential for exopolysaccharide biosynthesis in bacterial species typical in activated sludge (AS) systems based on genome mining and gene synteny analyses. Putative gene clusters associated with the biosynthesis of various exopolysaccharides were identified in AS bacteria. This study provides a comprehensive overview of the genome-resolved potential for these exopolysaccharides in AS bacteria and contributes to a better understanding of EPS composition in wastewater treatment systems.
Article
Engineering, Environmental
Giulia Dottorini, Dorottya Sarolta Wagner, Mikkel Stokholm-Bjerregaard, Sergey Kucheryavskiy, Thomas Yssing Michaelsen, Marta Nierychlo, Miriam Peces, Rohan Williams, Per Henrik Nielsen, Kasper Skytte Andersen, Per Halkjaer Nielsen
Summary: Well-functioning and stable microbial communities are critical for the operation of activated sludge wastewater treatment plants. Bioaugmentation has the potential to recover deteriorated systems or support specific processes, but its application in full-scale plants is problematic. In a transplantation experiment between two similar full-scale plants, the treatment performance and effluent quality remained stable, but the recipient plant's microbial community almost completely restored its pre-transplantation structure after 40 days. The addition of unique species from the donor AS was not successful in increasing the abundance of desired species or reducing unwanted bacteria in the recipient plant.
Article
Microbiology
Ayesha Z. Beg, Faraz Rashid, Absar Talat, Mohd Azam Haseen, Nadeem Raza, Kafil Akhtar, Morten Kam Dahl Dueholm, Asad U. Khan
Summary: The Fap operon of Pseudomonas aeruginosa plays a crucial role in pathoadaptation during pulmonary infection. Its presence increases pathogenesis and biofilm sustainability by modulating bacterial physiology. Targeting amyloids could be a potential clinical application to exploit the pathoadaptive role of Fap in pulmonary infections. The genetic conservation and extracellular exposure of Fap make it a commendable target for interventions.
MICROBIOLOGY SPECTRUM
(2023)
Article
Agricultural Engineering
Agnieszka Garlicka, Katarzyna Umiejewska, Per Halkjaer Nielsen, Adam Muszynski
Summary: The aim of this project was to increase methane production by combining feedstock pretreatment and co-digestion of maize silage with thickened excess sludge. Results showed that pretreatment of sludge alone increased methane production from 0.192 Nml/gVS (sludge + maize silage) to 0.220 Nml/gVS (pretreated sludge + maize silage). However, the energy balance indicated that the additional energy generated was not enough to cover the energy expenditure for the mechanical pretreatment. 16S rRNA gene amplicon sequencing revealed the composition of the microbial community, with Chloroflexi, Bacteroidota, Firmicutes, Proteobacteria, and Actinobacteriota being the most abundant bacteria phyla.
BIORESOURCE TECHNOLOGY
(2023)
Article
Engineering, Environmental
Martin Hjorth Andersen, Lisette Thomsen, Mikkel Stokholm-Bjerregaard, Susan Hove Hansen, Mads Albertsen, Per Halkjaer Nielsen, Soren Eriksen
Summary: The partial nitritation/anammox process is a popular approach for removing nitrogen from sidestreams, but it requires extensive surveillance and monitoring due to its sensitivity to disturbances. In this study, we utilized online sensor data and Nanopore DNA sequencing to monitor the microbial community and detect system disturbances in two full-scale deammonification reactors over a year. DNA surveillance revealed unexpected variations in anammox bacteria, and the composition and dynamics of the surrounding community indicated causes for occasional process disturbances. Monitoring the ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) could potentially optimize reactor operation. The use of frequent DNA sequencing was found to be an important supplement to online sensor data for process surveillance and control.
Article
Engineering, Environmental
Marie Riisgaard-Jensen, Giulia Dottorini, Marta Nierychlo, Per Halkjaer Nielsen
Summary: The immigration of bacteria in influent wastewater has a strong impact on the microbial community of activated sludge in wastewater treatment plants. The use of primary settlers can selectively increase or reduce the abundance of certain bacteria. The process of primary settling changes the microbial community of influent wastewater and can be a candidate for upstream control to optimize the assembly of microbial communities in activated sludge.
Article
Biotechnology & Applied Microbiology
Maarten D. Verhoeven, Per H. Nielsen, Morten K. D. Dueholm
Summary: The researchers introduced an experimental setup, combining 16S rRNA gene amplicon sequencing with plating of dispersed activated sludge bacteria, to rapidly identify the growth conditions that allow for the isolation of key microbial species in activated sludge. They found that agarose plates supplemented with various carbon sources support the growth of many previously uncultivated activated sludge bacteria.
APPLIED AND ENVIRONMENTAL MICROBIOLOGY
(2023)
Article
Engineering, Environmental
A. Margarida Teixeira, Ivone Vaz-Moreira, David Calderon-Franco, David Weissbrodt, Sabina Purkrtova, Stanislav Gajdos, Giulia Dottorini, Per Halkjaer Nielsen, Leron Khalifa, Eddie Cytryn, Jan Bartacek, Celia M. Manaia
Summary: Urban wastewater treatment plants (UWTPs) are crucial for reducing pollutant load and protecting water bodies, but they also emit antibiotic resistant bacteria and resistance genes, which have impacts on downstream environments. This study tested a set of biomarkers for antibiotic resistance monitoring and found that qPCR can be a cost-effective and technically accessible approach for monitoring wastewater and downstream environments.
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.
