SU\G(𝔸)/K·U
Sign Up for free Log In
Environmental Science › Pollution

Wastewater Treatment and Nitrogen Removal

Works Count: 85448

Description

This cluster of papers focuses on the microbial nitrogen cycle in biological wastewater treatment systems, including the roles of nitrifying and denitrifying bacteria, anammox bacteria, and extracellular polymeric substances. It covers topics such as complete nitrification, partial nitritation/anammox, biological phosphorus removal, and nitrous oxide emission during wastewater treatment.

Keywords

Nitrogen-Cycling Network; Anammox Bacteria; Extracellular Polymeric Substances; Nitrifying Bacteria; Denitrifying Bacteria; Biological Phosphorus Removal; Activated Sludge; Wastewater Treatment; Nitrous Oxide Emission; Anaerobic Ammonium Oxidation

Biological Wastewater Treatment: Principles, Modelling and Design

2008-09-01
Mogens Henze , Mark C.M. van Loosdrecht , GA Ekama +1 more
Available for subscribers to the IWA Publishing eBooks collection only.Over the past twenty years, the knowledge and understanding of wastewater treatment have advanced extensively and moved away from empirically-based approaches … Available for subscribers to the IWA Publishing eBooks collection only.Over the past twenty years, the knowledge and understanding of wastewater treatment have advanced extensively and moved away from empirically-based approaches to a first principles approach embracing chemistry, microbiology, physical and bioprocess engineering, and mathematics. Many of these advances have matured to the degree that they have been codified into mathematical models for simulation with computers. For a new generation of young scientists and engineers entering the wastewater treatment profession, the quantity, complexity and diversity of these new developments can be overwhelming, particularly in developing countries where access is not readily available to advanced level tertiary education courses in wastewater treatment.This book addresses this deficiency.It assembles and integrates the postgraduate course material of a dozen or so professors from research groups around the world that have made significant contributions to the advances in wastewater treatment.The book forms part of an internet-based curriculum in wastewater treatment which also includessummarized lecture handouts of the topics covered in bookfilmed lectures by the author professorstutorial exercises for students self-learningUpon completion of this curriculum the modern approach of modelling and simulation to wastewater treatment plant design and operation, be it activated sludge, biological nitrogen and phosphorus removal, secondary settling tanks or biofilm systems, can be embraced with deeper insight, advanced knowledge and greater confidence.ISBN: 9781780401867 (eBook)ISBN: 9781843391883 (Print)

Manual of environmental microbiology.

2007-01-01
C. J. Hurst , R.L. Crawford , Jay L. Garland +3 more
Section I: Introduction to Environmental Microbiology Section II: General Methodology Section III: Water Microbiology in Public Health Section IV: Aquatic Environments Section V: Soil, Rhizosphere and Phyllosphere Section VI: Subsurface … Section I: Introduction to Environmental Microbiology Section II: General Methodology Section III: Water Microbiology in Public Health Section IV: Aquatic Environments Section V: Soil, Rhizosphere and Phyllosphere Section VI: Subsurface and Landfills Section VII: Aerobiology Section VIII: Biotransformation and Biodegradation

Missing lithotroph identified as new planctomycete

1999-07-01
Marc Strous , John A. Fuerst , Evelien H. M. Kramer +6 more

Combination of 16S rRNA-targeted oligonucleotide probes with flow cytometry for analyzing mixed microbial populations

1990-06-01
Rudolf Amann , Brian J. Binder , Robert Olson +3 more
Fluorescent oligonucleotide hybridization probes were used to label bacterial cells for analysis by flow cytometry. The probes, complementary to short sequence elements within the 16S rRNA common to phylogenetically coherent … Fluorescent oligonucleotide hybridization probes were used to label bacterial cells for analysis by flow cytometry. The probes, complementary to short sequence elements within the 16S rRNA common to phylogenetically coherent assemblages of microorganisms, were labeled with tetramethylrhodamine and hybridized to suspensions of fixed cells. Flow cytometry was used to resolve individual target and nontarget bacteria (1 to 5 microns) via probe-conferred fluorescence. Target cells were quantified in an excess of nontarget cells. The intensity of fluorescence was increased additively by the combined use of two or three fluorescent probes complementary to different regions of the same 16S rRNA.
View PDF Chat

The ammonia monooxygenase structural gene amoA as a functional marker: molecular fine-scale analysis of natural ammonia-oxidizing populations

1997-12-01
Jan-henrich Rotthauwe , K.-P. Witzel , Werner Liesack
The naturally occurring genetic heterogeneity of autotrophic ammonia-oxidizing populations belonging to the beta subclass of the Proteobacteria was studied by using a newly developed PCR-based assay targeting a partial stretch … The naturally occurring genetic heterogeneity of autotrophic ammonia-oxidizing populations belonging to the beta subclass of the Proteobacteria was studied by using a newly developed PCR-based assay targeting a partial stretch of the gene which encodes the active-site polypeptide of ammonia monooxygenase (amoA). The PCR yielded a specific 491-bp fragment with all of the nitrifiers tested, but not with the homologous stretch of the particulate methane monooxygenase, a key enzyme of methane-oxidizing bacteria. The assay also specifically detected amoA in DNA extracted from various aquatic and terrestrial environments. The resulting PCR products retrieved from rice roots, activated sludge, a freshwater sample, and an enrichment culture were used for the generation of amoA gene libraries. No false positives were detected in a set of 47 randomly selected clone sequences that were analyzed further. The majority of the environmental sequences retrieved from rice roots and activated sludge grouped within the phylogenetic radiation defined by cultured strains of the genera Nitrosomonas and Nitrosospira. The comparative analysis identified members of both of these genera in activated sludge; however, only Nitrosospira-like sequences with very similar amino acid patterns were found on rice roots. Further differentiation of these molecular isolates was clearly possible on the nucleic acid level due to the accumulation of synonymous mutations, suggesting that several closely related but distinct Nitrosospira-like populations are the main colonizers of the rhizosphere of rice. Each of the amoA gene libraries obtained from the freshwater sample and the enrichment culture was dominated by a novel lineage that shared a branch with the Nitrosospira cluster but could not be assigned to any of the known pure cultures. Our data suggest that amoA represents a very powerful molecular tool for analyzing indigenous ammonia-oxidizing communities due to (i) its specificity, (ii) its fine-scale resolution of closely related populations, and (iii) the fact that a functional trait rather than a phylogenetic trait is detected.
View PDF Chat

The EPS Matrix: The “House of Biofilm Cells”

2007-08-04
Hans‐Curt Flemming , Thomas R. Neu , Daniel J. Wozniak
In response to a suggestion by the Biofilms 2007 organizing committee to hold an evening session on biofilm extracellular polymeric substances (EPS), an exceptionally inspiring event followed contributions by Ken … In response to a suggestion by the Biofilms 2007 organizing committee to hold an evening session on biofilm extracellular polymeric substances (EPS), an exceptionally inspiring event followed contributions by Ken Bayles, Alan Decho, Martina Hausner, Jan Kreft, Thomas Neu, Per Nielsen, Ute Romling,
View PDF Chat

Steam distillation methods for determination of ammonium, nitrate and nitrite

1965-01-01
J. M. Bremner , D. R. Keeney

Enzymatic activity in the activated-sludge floc matrix

1995-09-01
B. Fr olund , Thomas Griebe , Per Halkjær Nielsen

Deciphering the evolution and metabolism of an anammox bacterium from a community genome

2006-04-01
Marc Strous , Éric Pelletier , Sophie Mangenot +7 more

Treatment of organic pollution in industrial saline wastewater: A literature review

2006-10-28
Olivier Lefebvre , René Moletta

Use of p-nitrophenyl phosphate for assay of soil phosphatase activity

1969-11-01
M. A. Tabatabai , J. M. Bremner

Nitrous oxide emission during wastewater treatment

2009-03-12
Marlies J. Kampschreur , Hardy Temmink , Robbert Kleerebezem +2 more
View PDF Chat

The sequencing batch reactor as a powerful tool for the study of slowly growing anaerobic ammonium-oxidizing microorganisms

1998-11-27
Marc Strous , Joseph J. Heijnen , J. Gijs Kuenen +1 more

Autotrophic growth of anaerobic ammonium-oxidizing micro-organisms in a fluidized bed reactor

1996-08-01
A.A. van de Graaf , Peter de Bruijn , Lesley A. Robertson +2 more
An autotrophic, synthetic medium for the enrichment of anaerobic ammonium-oxidizing (Anammox) micro-organisms was developed. This medium contained ammonium and nitrite, as the only electron donor and electron acceptor, respectively, while … An autotrophic, synthetic medium for the enrichment of anaerobic ammonium-oxidizing (Anammox) micro-organisms was developed. This medium contained ammonium and nitrite, as the only electron donor and electron acceptor, respectively, while carbonate was the only carbon source provided. Preliminary studies showed that the presence of nitrite and the absence of organic electron donors were essential for Anammox activity. The conversion rate of the enrichment culture in a fluidized bed reactor was 3 kg NH4 + m−3 d−1 when fed with 30 mM NH4 +. This is equivalent to a specific anaerobic ammonium oxidation rate of 1000–1100 nmol NH4 +h−1 (mg volatile solids)−1. The maximum specific oxidation rate obtained was 1500 nmol NH4 +h−1 (mg volatile solids)−1. Per mol NH4 + oxidized, 0.041mol CO2 were incorporated, resulting in a estimated growth rate of 0.001 h−1. The main product of the Anammox reaction is N2, but about 10% of the N-feed is converted to NO3 −. The overall nitrogen balance gave a ratio of NH4 −-conversion to NO2 −-conversion and NO3 −-production of 1:1·31±0·06:2·02±0·02. During the conversion of NH4 + with NO2 −, no other intermediates or end-products such as hydroxylamine, NO and N2O could be detected. Acetylene, phosphate and oxygen were shown to be strong inhibitors of the Anammox activity. The dominant type of micro-organism in the enrichment culture was an irregularly shaped cell with an unusual morphology. During the enrichment for Anammox micro-organisms on synthetic medium, an increase in ether lipids was observed. The colour of the biomass changed from brownish to red, which was accompanied by an increase in the cytochrome content. Cytochrome spectra showed a peak at 470 nm gradually increasing in intensity during enrichment.
View PDF Chat

Sewage Treatment with Anammox

2010-05-06
Boran Kartal , J. Gijs Kuenen , Mark C.M. van Loosdrecht
Organic matter must be removed from sewage to protect the quality of the water bodies that it is discharged to. Most current sewage treatment plants are aimed at removing organic … Organic matter must be removed from sewage to protect the quality of the water bodies that it is discharged to. Most current sewage treatment plants are aimed at removing organic matter only. They are energy-inefficient, whereas potentially the organic matter could be regarded as a source of energy. However, organic carbon is not the only pollutant in sewage: Fixed nitrogen such as ammonium (NH4+) and nitrate (NO3−) must be removed to avoid toxic algal blooms in the environment. Conventional wastewater treatment systems for nitrogen removal require a lot of energy to create aerobic conditions for bacterial nitrification, and also use organic carbon to help remove nitrate by bacterial denitrification (see the figure). An alternative approach is the use of anoxic ammonium-oxidizing (anammox) bacteria, which require less energy ( 1 ) but grow relatively slowly. We explore process innovations that can speed up the anammox process and use all organic matter as much as possible for energy generation.

Extraction of extracellular polymers from activated sludge using a cation exchange resin

1996-08-01
B. Frølund , Rikke Palmgren , Kristian Keiding +1 more

Advances in enhanced biological phosphorus removal: From micro to macro scale

2007-04-17
Adrian Oehmen , Paulo C. Lemos , Gilda Carvalho +4 more

Role of nitrifier denitrification in the production of nitrous oxide

2001-10-01
N. Wrage , G.L. Velthof , M.L. van Beusichem +1 more

Extracellular polymeric substances (EPS) of microbial aggregates in biological wastewater treatment systems: A review

2010-08-11
Guo‐Ping Sheng , Han‐Qing Yu , Xiaoyan Li

Influence of loosely bound extracellular polymeric substances (EPS) on the flocculation, sedimentation and dewaterability of activated sludge

2006-09-07
X.Y. Li , Shu-Cheng Yang

The Domain-specific Probe EUB338 is Insufficient for the Detection of all Bacteria: Development and Evaluation of a more Comprehensive Probe Set

1999-09-01
Holger Daims , A. Brühl , Rudolf Amann +2 more

Experimental determination of nitrogen kinetic isotope fractionation: Some principles; illustration for the denitrification and nitrification processes

1981-10-01
André Mariotti , J. C. Germon , P. Hubert +4 more

Activated Sludge Model No. 3

1999-01-01
Willi Gujer , Mogens Henze , Takahashi Mino +1 more
The Activated Sludge Model No. 3 (ASM3) can predict oxygen consumption, sludge production, nitrification and denitrification of activated sludge systems. It relates to the Activated Sludge Model No. 1 (ASM1) … The Activated Sludge Model No. 3 (ASM3) can predict oxygen consumption, sludge production, nitrification and denitrification of activated sludge systems. It relates to the Activated Sludge Model No. 1 (ASM1) and corrects for some defects of ASM1. In addition to ASM1, ASM3 includes storage of organic substrates as a new process. The lysis (decay) process is exchanged for an endogenous respiration process. ASM3 is provided as a reference in a form which can be implemented in a computer code without further adjustments. Typical kinetic and stoichiometric parameters are provided for 10°C and 20°C together with the composition of a typical primary effluent in terms of the model components.

Biological Nitrogen Fixation

1993-07-01
Robert H. Burris , Gary P. Roberts
The objective of this review is to provide an overview of intermittent fasting regimens, summarize the evidence on the health benefits of intermittent fasting, and discuss physiological mechanisms by which … The objective of this review is to provide an overview of intermittent fasting regimens, summarize the evidence on the health benefits of intermittent fasting, and discuss physiological mechanisms by which intermittent fasting might lead to improved ...Read More

Use of the upflow sludge blanket (USB) reactor concept for biological wastewater treatment, especially for anaerobic treatment

1980-04-01
G. Lettinga , A.F.M. van Velsen , S.W. Hobma +2 more
In recent years considerable effort has been made in the Netherlands toward the development of a more sophisticated anaerobic treatment process, suitable for treating low a strength wastes and for … In recent years considerable effort has been made in the Netherlands toward the development of a more sophisticated anaerobic treatment process, suitable for treating low a strength wastes and for applications at liquid detention times of 3–4 hr. The efforts have resulted in new type of upflow anaerobic sludge blanket (UASB) process, which in recent 6 m3 pilot-plant experiments has shown to be capable of handling organic space loads of 15–40 kg chemical oxygen demand (COD)·m−3/day at 3–8 hr liquid detention times. In the first 200 m3 full-scale plant of the UASB concept, organic space loadings of up to 16 kg COD·m−3/day could be treated satisfactorily at a detention times of 4 hr, using sugar beet waste as feed. The main results obtained with the process in the laboratory as well as in 6 m3 pilot plant and 200 m3 full-scale experiments are presented and evaluated in this paper. Special attention is given to the main operating characteristics of the UASB reactor concept. Moreover, some preliminary results are presented of laboratory experiments concerning the use of the USB reactor concept for denitrification as well as for the acid formation step in anaerobic treatment. For both purposes the process looks feasible because very satisfactory results with respect to denitrification and acid formation can be achieved at very high hydraulic loads (12 day−1) and high organic loading rates, i.e., 20 kg COD·m−3/day in the denitrification and 60–80 kg COD·m−3/day in the acid formation experiments.

Extraction of extracellular polymeric substances (EPS) of sludges

2002-05-01
Hong Liu , Herbert H. P. Fang

A mathematical model for the continuous culture of microorganisms utilizing inhibitory substrates

1968-11-01
John F. Andrews
Abstract A mathematical model is presented for both batch and continuous cultures of microorganisms utilizing inhibitory substrates. The key feature of the model is the use of a inhibition function … Abstract A mathematical model is presented for both batch and continuous cultures of microorganisms utilizing inhibitory substrates. The key feature of the model is the use of a inhibition function to relate substrate concentration and specific growth rate. Simulation studies show that the primary result of inhibition by substrate in a batch culture is an increase in the lag time whereas in continuous culture inhibition by substrate may result in process instability. The model should be of value in investigations of the stability of biological processes used for the treatment of certain industrial wastes such as those containing phenols, thiocyanates, nitrates, ammonia, volatile acids, etc., which are known to be inhibitory to many of the organisms metabolizing them.

Ammonia-Oxidizing Bacteria: A Model for Molecular Microbial Ecology

2001-10-01
George A. Kowalchuk , J. Stephen
▪ Abstract The eutrophication of many ecosystems in recent decades has led to an increased interest in the ecology of nitrogen transformation. Chemolitho-autotrophic ammonia-oxidizing bacteria are responsible for the rate-limiting … ▪ Abstract The eutrophication of many ecosystems in recent decades has led to an increased interest in the ecology of nitrogen transformation. Chemolitho-autotrophic ammonia-oxidizing bacteria are responsible for the rate-limiting step of nitrification in a wide variety of environments, making them important in the global cycling of nitrogen. These organisms are unique in their ability to use the conversion of ammonia to nitrite as their sole energy source. Because of the importance of this functional group of bacteria, understanding of their ecology and physiology has become a subject of intense research over recent years. The monophyletic nature of these bacteria in terrestrial environments has facilitated molecular biological approaches in studying their ecology, and progress in this field has been rapid. The ammonia-oxidizing bacteria of the β-subclass Proteobacteria have become somewhat of a model system within molecular microbial ecology, and this chapter reviews recent progress in our knowledge of their distribution, diversity, and ecology.

Have we overemphasized the role of denitrification in aquatic ecosystems? A review of nitrate removal pathways

2007-03-01
Amy J. Burgin , Stephen K. Hamilton
The removal of nitrogen (N) in aquatic ecosystems is of great interest because excessive nitrate in groundwater and surface water is a growing problem. High nitrate loading degrades water quality … The removal of nitrogen (N) in aquatic ecosystems is of great interest because excessive nitrate in groundwater and surface water is a growing problem. High nitrate loading degrades water quality and is linked to eutrophication and harmful algal blooms, especially in coastal marine waters. Past research on nitrate removal processes has emphasized plant or microbial uptake (assimilation) or respiratory denitrification by bacteria. The increasing application of stable isotopes and other tracer techniques to the study of nitrate removal has yielded a growing body of evidence for alternative, microbially mediated processes of nitrate transformation. These include dissimilatory (the reduction of nitrogen into other inorganic compounds, coupled to energy producing processes) reduction of nitrate to ammonium (DNRA), chemoautotrophic denitrification via sulfur or iron oxidation, and anaerobic ammonium oxidation (anammox), as well as abiotic nitrate removal processes. Here, we review evidence for the importance of alternative nitrate removal pathways in aquatic ecosystems and discuss how the possible prevalence of these pathways may alter views of N cycling and its controls. These alternative pathways are of particular importance for the management of excess N in the environment, especially in cases where nitrate is transformed to ammonium, a biologically available and less mobile N form, rather than to dinitrogen gas.
View PDF Chat

Anaerobic ammonium oxidation discovered in a denitrifying fluidized bed reactor

1995-03-01
A. Mulder , A.A. van de Graaf , Lesley A. Robertson +1 more
Until now, oxidation of ammonium has only been known to proceed under aerobic conditions. Recently, we observed that NH4+ was disappearing from a denitrifying fluidized bed reactor treating effluent from … Until now, oxidation of ammonium has only been known to proceed under aerobic conditions. Recently, we observed that NH4+ was disappearing from a denitrifying fluidized bed reactor treating effluent from a methanogenic reactor. Both nitrate and ammonium consumption increased with concomitant gas production. A maximum ammonium removal rate of 0.4 kg N · m−3 · d−1 (1.2 mM/h) was observed. The evidence for this anaerobic ammonium oxidation was based on nitrogen and redox balances in continuous-flow experiments. It was shown that for the oxidation of 5 mol ammonium, 3 mol nitrate were required, resulting in the formation of 4 mol dinitrogen gas. Subsequent batch experiments confirmed that the NH4+ conversion was nitrate dependent. It was concluded that anaerobic ammonium oxidation is a new process in which ammonium is oxidized with nitrate serving as the electron acceptor under anaerobic conditions, producing dinitrogen gas. This biological process has been given the name ‘Anammox” (anaerobic ammonium oxidation), and has been patented.
View PDF Chat

Phylogeny of All Recognized Species of Ammonia Oxidizers Based on Comparative 16S rRNA and <i>amoA</i> Sequence Analysis: Implications for Molecular Diversity Surveys

2000-12-01
Ulrike Purkhold , Andreas Pommerening‐Röser , Stefan Juretschko +3 more
ABSTRACT The current perception of evolutionary relationships and the natural diversity of ammonia-oxidizing bacteria (AOB) is mainly based on comparative sequence analyses of their genes encoding the 16S rRNA and … ABSTRACT The current perception of evolutionary relationships and the natural diversity of ammonia-oxidizing bacteria (AOB) is mainly based on comparative sequence analyses of their genes encoding the 16S rRNA and the active site polypeptide of the ammonia monooxygenase (AmoA). However, only partial 16S rRNA sequences are available for many AOB species and most AOB have not yet been analyzed on the amoA level. In this study, the 16S rDNA sequence data of 10 Nitrosomonas species and Nitrosococcus mobilis were completed. Furthermore, previously unavailable 16S rRNA sequences were determined for three Nitrosomonas sp. isolates and for the gamma-subclass proteobacterium Nitrosococcus halophilus . These data were used to revaluate the specificities of published oligonucleotide primers and probes for AOB. In addition, partial amoA sequences of 17 AOB, including the above-mentioned 15 AOB, were obtained. Comparative phylogenetic analyses suggested similar but not identical evolutionary relationships of AOB by using 16S rRNA and AmoA as marker molecules, respectively. The presented 16S rRNA and amoA and AmoA sequence data from all recognized AOB species significantly extend the currently used molecular classification schemes for AOB and now provide a more robust phylogenetic framework for molecular diversity inventories of AOB. For 16S rRNA-independent evaluation of AOB species-level diversity in environmental samples, amoA and AmoA sequence similarity threshold values were determined which can be used to tentatively identify novel species based on cloned amoA sequences. Subsequently, 122 amoA sequences were obtained from 11 nitrifying wastewater treatment plants. Phylogenetic analyses of the molecular isolates showed that in all but two plants only nitrosomonads could be detected. Although several of the obtained amoA sequences were only relatively distantly related to known AOB, none of these sequences unequivocally suggested the existence of previously unrecognized species in the wastewater treatment environments examined.
View PDF Chat

Key Physiology of Anaerobic Ammonium Oxidation

1999-07-01
Marc Strous , J. Gijs Kuenen , Mike S. M. Jetten
ABSTRACT The physiology of anaerobic ammonium oxidizing (anammox) aggregates grown in a sequencing batch reactor was investigated quantitatively. The physiological pH and temperature ranges were 6.7 to 8.3 and 20 … ABSTRACT The physiology of anaerobic ammonium oxidizing (anammox) aggregates grown in a sequencing batch reactor was investigated quantitatively. The physiological pH and temperature ranges were 6.7 to 8.3 and 20 to 43°C, respectively. The affinity constants for the substrates ammonium and nitrite were each less than 0.1 mg of nitrogen per liter. The anammox process was completely inhibited by nitrite concentrations higher than 0.1 g of nitrogen per liter. Addition of trace amounts of either of the anammox intermediates (1.4 mg of nitrogen per liter of hydrazine or 0.7 mg of nitrogen per liter of hydroxylamine) restored activity completely.
View PDF Chat

Ammonia oxidation kinetics determine niche separation of nitrifying Archaea and Bacteria

2009-09-30
Willm Martens‐Habbena , Paul M. Berube , Hidetoshi Urakawa +2 more

Cell biology and molecular basis of denitrification

1997-12-01
Walter G. Zumft
Denitrification is a distinct means of energy conservation, making use of N oxides as terminal electron acceptors for cellular bioenergetics under anaerobic, microaerophilic, and occasionally aerobic conditions. The process is … Denitrification is a distinct means of energy conservation, making use of N oxides as terminal electron acceptors for cellular bioenergetics under anaerobic, microaerophilic, and occasionally aerobic conditions. The process is an essential branch of the global N cycle, reversing dinitrogen fixation, and is associated with chemolithotrophic, phototrophic, diazotrophic, or organotrophic metabolism but generally not with obligately anaerobic life. Discovered more than a century ago and believed to be exclusively a bacterial trait, denitrification has now been found in halophilic and hyperthermophilic archaea and in the mitochondria of fungi, raising evolutionarily intriguing vistas. Important advances in the biochemical characterization of denitrification and the underlying genetics have been achieved with Pseudomonas stutzeri, Pseudomonas aeruginosa, Paracoccus denitrificans, Ralstonia eutropha, and Rhodobacter sphaeroides. Pseudomonads represent one of the largest assemblies of the denitrifying bacteria within a single genus, favoring their use as model organisms. Around 50 genes are required within a single bacterium to encode the core structures of the denitrification apparatus. Much of the denitrification process of gram-negative bacteria has been found confined to the periplasm, whereas the topology and enzymology of the gram-positive bacteria are less well established. The activation and enzymatic transformation of N oxides is based on the redox chemistry of Fe, Cu, and Mo. Biochemical breakthroughs have included the X-ray structures of the two types of respiratory nitrite reductases and the isolation of the novel enzymes nitric oxide reductase and nitrous oxide reductase, as well as their structural characterization by indirect spectroscopic means. This revealed unexpected relationships among denitrification enzymes and respiratory oxygen reductases. Denitrification is intimately related to fundamental cellular processes that include primary and secondary transport, protein translocation, cytochrome c biogenesis, anaerobic gene regulation, metalloprotein assembly, and the biosynthesis of the cofactors molybdopterin and heme D1. An important class of regulators for the anaerobic expression of the denitrification apparatus are transcription factors of the greater FNR family. Nitrate and nitric oxide, in addition to being respiratory substrates, have been identified as signaling molecules for the induction of distinct N oxide-metabolizing enzymes.

Full-scale partial nitritation/anammox experiences – An application survey

2014-02-25
Susanne Lackner , Eva M. Gilbert , Siegfried E. Vlaeminck +3 more
Partial nitritation/anammox (PN/A) has been one of the most innovative developments in biological wastewater treatment in recent years. With its discovery in the 1990s a completely new way of ammonium … Partial nitritation/anammox (PN/A) has been one of the most innovative developments in biological wastewater treatment in recent years. With its discovery in the 1990s a completely new way of ammonium removal from wastewater became available. Over the past decade many technologies have been developed and studied for their applicability to the PN/A concept and several have made it into full-scale. With the perspective of reaching 100 full-scale installations in operation worldwide by 2014 this work presents a summary of PN/A technologies that have been successfully developed, implemented and optimized for high-strength ammonium wastewaters with low C:N ratios and elevated temperatures. The data revealed that more than 50% of all PN/A installations are sequencing batch reactors, 88% of all plants being operated as single-stage systems, and 75% for sidestream treatment of municipal wastewater. Additionally an in-depth survey of 14 full-scale installations was conducted to evaluate practical experiences and report on operational control and troubleshooting. Incoming solids, aeration control and nitrate built up were revealed as the main operational difficulties. The information provided gives a unique/new perspective throughout all the major technologies and discusses the remaining obstacles.
View PDF Chat

The influence of soil pH on the diversity, abundance and transcriptional activity of ammonia oxidizing archaea and bacteria

2008-08-14
Graeme W. Nicol , Sven Leininger , Christa Schleper +1 more
Summary Autotrophic ammonia oxidation occurs in acid soils, even though laboratory cultures of isolated ammonia oxidizing bacteria fail to grow below neutral pH. To investigate whether archaea possessing ammonia monooxygenase … Summary Autotrophic ammonia oxidation occurs in acid soils, even though laboratory cultures of isolated ammonia oxidizing bacteria fail to grow below neutral pH. To investigate whether archaea possessing ammonia monooxygenase genes were responsible for autotrophic nitrification in acid soils, the community structure and phylogeny of ammonia oxidizing bacteria and archaea were determined across a soil pH gradient (4.9–7.5) by amplifying 16S rRNA and amoA genes followed by denaturing gradient gel electrophoresis (DGGE) and sequence analysis. The structure of both communities changed with soil pH, with distinct populations in acid and neutral soils. Phylogenetic reconstructions of crenarchaeal 16S rRNA and amo A genes confirmed selection of distinct lineages within the pH gradient and high similarity in phylogenies indicated a high level of congruence between 16S rRNA and amoA genes. The abundance of archaeal and bacterial amoA gene copies and mRNA transcripts contrasted across the pH gradient. Archaeal amoA gene and transcript abundance decreased with increasing soil pH, while bacterial amoA gene abundance was generally lower and transcripts increased with increasing pH. Short‐term activity was investigated by DGGE analysis of gene transcripts in microcosms containing acidic or neutral soil or mixed soil with pH readjusted to that of native soils. Although mixed soil microcosms contained identical archaeal ammonia oxidizer communities, those adapted to acidic or neutral pH ranges showed greater relative activity at their native soil pH. Findings indicate that different bacterial and archaeal ammonia oxidizer phylotypes are selected in soils of different pH and that these differences in community structure and abundances are reflected in different contributions to ammonia oxidizer activity. They also suggest that both groups of ammonia oxidizers have distinct physiological characteristics and ecological niches, with consequences for nitrification in acid soils.

Startup of reactors for anoxic ammonium oxidation: Experiences from the first full-scale anammox reactor in Rotterdam

2007-06-22
Wouter R. L. van der Star , Wiebe Abma , Dennis Blommers +5 more

Anaerobic ammonium oxidation by anammox bacteria in the Black Sea

2003-04-01
Marcel M. M. Kuypers , Olav Sliekers , Gaute Lavik +6 more

Production of N<sub>2</sub>through Anaerobic Ammonium Oxidation Coupled to Nitrate Reduction in Marine Sediments

2002-03-01
Bo Thamdrup , Tage Dalsgaard
ABSTRACT In the global nitrogen cycle, bacterial denitrification is recognized as the only quantitatively important process that converts fixed nitrogen to atmospheric nitrogen gas, N 2 , thereby influencing many … ABSTRACT In the global nitrogen cycle, bacterial denitrification is recognized as the only quantitatively important process that converts fixed nitrogen to atmospheric nitrogen gas, N 2 , thereby influencing many aspects of ecosystem function and global biogeochemistry. However, we have found that a process novel to the marine nitrogen cycle, anaerobic oxidation of ammonium coupled to nitrate reduction, contributes substantially to N 2 production in marine sediments. Incubations with 15 N-labeled nitrate or ammonium demonstrated that during this process, N 2 is formed through one-to-one pairing of nitrogen from nitrate and ammonium, which clearly separates the process from denitrification. Nitrite, which accumulated transiently, was likely the oxidant for ammonium, and the process is thus similar to the anammox process known from wastewater bioreactors. Anaerobic ammonium oxidation accounted for 24 and 67% of the total N 2 production at two typical continental shelf sites, whereas it was detectable but insignificant relative to denitrification in a eutrophic coastal bay. However, rates of anaerobic ammonium oxidation were higher in the coastal sediment than at the deepest site and the variability in the relative contribution to N 2 production between sites was related to large differences in rates of denitrification. Thus, the relative importance of anaerobic ammonium oxidation and denitrification in N 2 production appears to be regulated by the availability of their reduced substrates. By shunting nitrogen directly from ammonium to N 2 , anaerobic ammonium oxidation promotes the removal of fixed nitrogen in the oceans. The process can explain ammonium deficiencies in anoxic waters and sediments, and it may contribute significantly to oceanic nitrogen budgets.
View PDF Chat

Complete nitrification by a single microorganism

2015-11-26
Maartje A. H. J. van Kessel , Daan R. Speth , Mads Albertsen +5 more
View PDF Chat

Complete nitrification by Nitrospira bacteria

2015-11-26
Holger Daims , Е. В. Лебедева , Petra Pjevac +7 more

Enzymatic Basis for Active Transport of Na<sup>+</sup> and K<sup>+</sup> Across Cell Membrane

1965-07-01
J.C. Skou

Activated Sludge Models ASM1, ASM2, ASM2d and ASM3

2015-12-21
Mogens Henze , Willi Gujer , Takashi Mino +1 more
This book has been produced to give a total overview of the Activated Sludge Model (ASM) family at the start of 2000 and to give the reader easy access to … This book has been produced to give a total overview of the Activated Sludge Model (ASM) family at the start of 2000 and to give the reader easy access to the different models in their original versions. It thus presents ASM1, ASM2, ASM2d and ASM3 together for the first time. Modelling of activated sludge processes has become a common part of the design and operation of wastewater treatment plants. Today models are being used in design, control, teaching and research. Contents This title belongs to Scientific and Technical Report Series ISBN: 9781900222242 (Print) ISBN: 9781780402369 (eBook)

The microbial nitrogen-cycling network

2018-02-05
Marcel M. M. Kuypers , Hannah K. Marchant , Boran Kartal
View PDF Chat

Inhibition of nitrification by ammonia and nitrous acid

1976-01-01
Arthur C. Anthonisen , R.C. Loehr , T. B. S. Prakasam +1 more
THE IMPORTANCE OF NITRIFICATION has been recognized for more than a cen tury. Engineers and scientists continue to investigate the process to obtain a better understanding of the fundamentals and … THE IMPORTANCE OF NITRIFICATION has been recognized for more than a cen tury. Engineers and scientists continue to investigate the process to obtain a better understanding of the fundamentals and to use the process for the benefit of man. Controlled nitrification may occur during waste treatment, and engineers have begun to incorporate the process as part of nitri fication-denitrification systems for nitrogen control preceding discharge of the treated wastes.

Cell biology and molecular basis of denitrification.

1997-01-01
Walter G. Zumft

Anaerobic ammonium oxidation discovered in a denitrifying fluidized bed reactor

1995-03-01
A. Mulder , A.A. van de Graaf , Lesley A. Robertson +1 more
Until now, oxidation of ammonium has only been known to proceed under aerobic conditions. Recently, we observed that NH4+ was disappearing from a denitrifying fluidized bed reactor treating effluent from … Until now, oxidation of ammonium has only been known to proceed under aerobic conditions. Recently, we observed that NH4+ was disappearing from a denitrifying fluidized bed reactor treating effluent from a methanogenic reactor. Both nitrate and ammonium consumption increased with concomitant gas production. A maximum ammonium removal rate of 0.4 kg N · m−3 · d−1 (1.2 mM/h) was observed. The evidence for this anaerobic ammonium oxidation was based on nitrogen and redox balances in continuous-flow experiments. It was shown that for the oxidation of 5 mol ammonium, 3 mol nitrate were required, resulting in the formation of 4 mol dinitrogen gas. Subsequent batch experiments confirmed that the NH4+ conversion was nitrate dependent. It was concluded that anaerobic ammonium oxidation is a new process in which ammonium is oxidized with nitrate serving as the electron acceptor under anaerobic conditions, producing dinitrogen gas. This biological process has been given the name 'Anammox" (anaerobic ammonium oxidation), and has been patented.
View PDF Chat

[Isolation and nitrogen transformation characterization of a moderately halophilic nitrification-aerobic denitrification strain

2025-06-25
Zhenxing Xie , Yun Wang , Gang-Qiang Jiang +6 more | PubMed
The biological nitrogen removal technology utilizing heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria has shown effectiveness in wastewater treatment. However, the nitrogen removal efficiency of HN-AD bacteria significantly decreases as the salinity … The biological nitrogen removal technology utilizing heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria has shown effectiveness in wastewater treatment. However, the nitrogen removal efficiency of HN-AD bacteria significantly decreases as the salinity increases. To tackle the challenge of treating high-salt and high-nitrogen wastewater, we isolated a moderately halophilic HN-AD strain 5505 from a salt lake in Xinjiang. The strain was identified based on morphological, physiological, and biochemical characteristics and the 16S rRNA gene sequence. Single-factor experiments were carried out with NH4+-N, NO3--N, and NO2--N as sole or mixed nitrogen sources to study the nitrifying effect, denitrifying effect, and nitrogen metabolism pathway of the strain. The strain was identified as Halomonas sp.. It can grow in the presence of 1%-25% (W/V) NaCl and exhibited efficient nitrogen removal ability in the presence of 3%-8% NaCl. At the optimal NaCl concentration (8%), the strain showed the NH4+-N, NO3--N and NO2--N removal rates of 100.0%, 94.11% and 74.43%, respectively. Strain 5505 removed inorganic nitrogen mainly by assimilation, which accounted for over 62.68% of total nitrogen removal. In the presence of mixed nitrogen sources, strain 5505 showed a preference for utilizing ammonia, with a potential HN-AD pathway of NH4+→NH2OH→NO2-→NO3-→NO2-→NO/N2O/N2. The findings provide efficient salt-tolerant bacterial resources, enhance our understanding of biological nitrogen removal, and contribute to the nitrogen removal efficiency improvement in the treatment of high-salt and high-nitrogen wastewater.

Effect of biocarrier on Dirammox during high NH4+-N wastewater treatment: Microbial community, sludge property, and removal efficiency

2025-06-25
Yuchen Yuan , Xiaochen Xu , Fenglin Yang +1 more | Journal of Water Process Engineering

Impact of dual nitrification on denitrification potential and process configuration at elevated temperatures – experimental appraisal and modeling

2025-06-24
Didem Güven , Emine Ubay Çokgör , Seval Sözen +1 more | Journal of Chemical Technology & Biotechnology
Abstract BACKGROUND Leachate has a rare asset of dissipating heat energy, triggering elevated temperatures in the reactor volume, due to its excessive organic matter (chemical oxygen demand – COD) content. … Abstract BACKGROUND Leachate has a rare asset of dissipating heat energy, triggering elevated temperatures in the reactor volume, due to its excessive organic matter (chemical oxygen demand – COD) content. This paper elaborated this asset to investigate its impact on the growth kinetics of the two microbial groups responsible for the sequential oxidation of ammonia to nitrate. It also performed a model evaluation of microbial kinetics to explore the merit of using nitrite for the sustainable leachate treatment via nitrogen removal and control. RESULTS Experimental evidence showed that the residual energy in leachate sustained a high temperature of 35 °C in the reactor volume under summer conditions. The functional relationship at this temperature between aerobic sludge age ( θ XA ) and respective ammonia, nitrite and nitrate profiles indicated that it was possible to segregate oxidized nitrogen compounds where nitrite became the dominant fraction for θ XA values between 4.0 and 5.0 days, and nitrate above 6.0 days, offering the possibility of using nitrite as an electron acceptor in denitrification. The highly biodegradable nature of COD ascertained by COD fractionation experiments provided enough denitrification potential to remove all nitrite available within an unusually small anoxic volume of 10% of the total reactor volume. CONCLUSION Results, both experimental and modeling, enabled to propose and justify an innovative operational scheme based on nitrite recycling and for sustainable nitrogen removal with a total sludge age lower than 6.0 days. This sludge age level represents a borderline level of what is considered to be a high rate activated sludge process designed only for organic carbon removal. © 2025 Society of Chemical Industry (SCI).

Contribution of denitrification and ammonia oxidation to nitrous oxide emissions from three organic soilless substrates

2025-06-24
Bruno J. L. Pitton , Lorence R. Oki , Richard Y. Evans +1 more | The Science of The Total Environment
Nitrous oxide (N2O) emissions from soilless growing substrates are significantly greater per production area than crops grown in mineral soil. To understand and identify the N2O production pathways in soilless … Nitrous oxide (N2O) emissions from soilless growing substrates are significantly greater per production area than crops grown in mineral soil. To understand and identify the N2O production pathways in soilless substrates, fir bark, peat, and peat:fir bark substrates were treated with labeled 15N fertilizers. The volumetric water content (VWC) of the soilless substrate was maintained near container capacity, and gas samples were collected every other day for 21 days and analyzed for 15N-N2O content. Fir bark and peat:fir bark substrates had significantly greater total N2O emissions than peat substrate when fertilized with NH4NO3. Denitrification was the main pathway of N2O emissions from all substrates and it was more pronounced in the fir bark and peat:fir bark substrates. In the peat substrate, the contribution of ammonia oxidation to N2O emissions started on day 11 and continued to increase until the end of the experiment, contributing to 6 % of the total N2O emitted from this substrate. Overall, reducing denitrification-derived emissions from soilless substrates is critical to mitigate the impact of container-plant production on global warming. Future research should focus on developing strategies to reduce these emissions.

Nitrous oxide emissions induced by antibiotics during denitrification: the mediating role of carbon source on energy metabolism and electron transport chain

2025-06-24
Anqing Fu , Qiqi Chen , Yuanjun Peng +4 more | Journal of Cleaner Production

Integrated fixed-film activated sludge and the derivative process: a review of carrier design, microbial regulation, and enhanced nitrogen removal in wastewater treatment

2025-06-24
Ruizhe Wang , Dong Li , Bin Lü +1 more | Journal of Water Process Engineering

Dynamic response of pH to NO2− and S0 directional accumulation during sulfur autotrophic denitrification

2025-06-24
Pengze Dang , Yayi Wang , Chen Lyu +7 more | Journal of Environmental Management

Insights into Aeration Intensification in Biofilm Reactors for Efficient Wastewater Treatment

2025-06-23
Hassimi Abu Hasan , Nur Asyiqin Azahar , Mohd Hafizuddin Muhamad | Water
Aeration used in wastewater treatment is energy-intensive, subsequently increasing the cost of treatment. Aeration is used to supply oxygen that is required for bacterial metabolism that degrades organic compounds in … Aeration used in wastewater treatment is energy-intensive, subsequently increasing the cost of treatment. Aeration is used to supply oxygen that is required for bacterial metabolism that degrades organic compounds in wastewater. In this review, we will focus on the effect of aeration rates on the performance of biofilm-based technologies for wastewater treatment and the evaluation of the oxygen transfer rate (OTR) of these technologies. The performance of biofilm reactors in terms of removal efficiency increases with air flow rate, as increased flow helps to increase the contact area between wastewater and the biofilm on the carrier. The same is true for the OTR due to the greater availability of oxygen at higher airflow rates. Excessive aeration can negatively affect wastewater treatment through biofilm shearing and detachment from the carrier. Through a critical review of these technologies, the optimal air flow rate and aeration methods can be determined in biofilm reactors to improve the quality of the treated water, increase the efficiency of the aeration system, and attain energy savings.

Mechanistic Insights into the Contrasting Effects of Low DO on Nitrification-Derived N<sub>2</sub>O Emissions in Comammox <i>Nitrospira</i>- versus AOB-Dominated Sludge

2025-06-23
Wanyi Liang , Deyong Li , Jiaying Wang +3 more | Environmental Science & Technology
Nitrification significantly contributes to N2O emissions in wastewater treatment, typically enhanced at low dissolved oxygen (DO). The present study revealed that low DO (∼0.2 mg/L) enhanced the N2O emission factor … Nitrification significantly contributes to N2O emissions in wastewater treatment, typically enhanced at low dissolved oxygen (DO). The present study revealed that low DO (∼0.2 mg/L) enhanced the N2O emission factor (EF) from nitrification by 4.5 times in canonical ammonia-oxidizing bacteria (AOB)-dominated sludge, while it reduced N2O EF by 73% in comammox Nitrospira-dominated sludge. During nitrification, the accumulation of intermediate NH2OH in AOB-dominant sludge was much higher and increased more significantly by low DO (from 0.018 to 0.067 mg-N/L) compared to comammox Nitrospira-dominant sludge (from 0.004 to 0.009 mg-N/L). In AOB-dominant sludge, the increased NH2OH and upregulated AOB-NOR gene at low DO promoted NO reduction, thus increasing N2O EF while simultaneously decreasing NO emission. In the comammox Nitrospira-dominant sludge, N2O was primarily produced via abiotic pathways. Further investigation found that N2O production decreased significantly under low DO in inactivated sludge and pure water with the sole addition of NH2OH, suggesting that low DO inhibited N2O formation via abiotic NH2OH oxidation. Therefore, in comammox Nitrospira-dominant sludge, low DO decreased N2O production primarily due to the inhibition of low DO to N2O formation via abiotic NH2OH oxidation and the low NH2OH accumulation. These results imply that enriching comammox Nitrospira in the wastewater treatment process can ensure stably low N2O emissions regardless of the variations in DO.

Removal of organic matter and nitrogen in a single reactor with extremely high sludge age and cyclic aeration

2025-06-23
Gloria Jaqueline Correa-Restrepo , Francisco Molina , Álvaro Arango-Ruiz +2 more | Water Science & Technology
ABSTRACT The removal of organic matter and total nitrogen (TN) in domestic wastewater was evaluated in a full-scale activated sludge (AS) system, operating with Extremely High Sludge Ages (EHSA) and … ABSTRACT The removal of organic matter and total nitrogen (TN) in domestic wastewater was evaluated in a full-scale activated sludge (AS) system, operating with Extremely High Sludge Ages (EHSA) and cyclic aeration under continuous flow. A single bioreactor was used, applying intermittent aeration with a 45′:15′ on/off cycle. The results were obtained through 6 composite sampling periods of 24 h each. The sludge age was approximately 180 days, with average removals of chemical oxygen demand (COD) and TN of 88.6 and 71.7%, respectively. The obtained results save 6 h of energy per day and enable the conversion of conventional AS reactors into tertiary treatment by removing nitrogen, involving minimal investment in the same secondary treatment without constructing additional tanks. Similarly, the very high sludge ages lead to a reduction in construction costs, as the volume can be decreased due to shorter hydraulic detention times. Additionally, the minimal generation of purge sludge results in reduced costs for its final disposal and fewer environmental issues associated with its management.

Screening and characterization of an Alcaligenes sp. HHVWA23 and the efficiency of nitrogen removal by biochar immobilization

2025-06-21
Teng Li , Chang Liu , Zhihua Xi +5 more | Journal of Environmental Management

Ammonium-Generating Microbial Consortia in Paddy Soil Revealed by DNA-Stable Isotope Probing and Metatranscriptomics

2025-06-21
Chao-Nan Wang , Yoko Masuda , Keishi Senoo | Microorganisms
Rice paddy fields are sustainable agricultural systems as soil microorganisms help maintain nitrogen fertility through generating ammonium. In these soils, dissimilatory nitrate reduction to ammonium (DNRA), nitrogen fixation, and denitrification … Rice paddy fields are sustainable agricultural systems as soil microorganisms help maintain nitrogen fertility through generating ammonium. In these soils, dissimilatory nitrate reduction to ammonium (DNRA), nitrogen fixation, and denitrification are closely linked. DNRA and denitrification share the same initial steps and nitrogen gas, the end product of denitrification, can serve as a substrate for nitrogen fixation. However, the microorganisms responsible for these three reductive nitrogen transformations, particularly those focused on ammonium generation, have not been comprehensively characterized. In this study, we used stable isotope probing with 15NO3−, 15N2O, and 15N2, combined with 16S rRNA high-throughput sequencing and metatranscriptomics, to identify ammonium-generating microbial consortia in paddy soils. Our results revealed that several bacterial families actively contribute to ammonium generation under different nitrogen substrate conditions. Specifically, Geobacteraceae (N2O and +N2), Bacillaceae (+NO3− and +N2), Rhodocyclaceae (+N2O and +N2), Anaeromyxobacteraceae (+NO3− and +N2O), and Clostridiaceae (+NO3− and +N2) were involved. Many of these bacteria participate in key ecological processes typical of paddy environments, including iron or sulfate reduction and rice straw decomposition. This study revealed the ammonium-generating microbial consortia in paddy soil that contain several key bacterial drivers of multiple reductive nitrogen transformations and suggested their diverse functions in paddy soil metabolism.

Hydrazine-mediated control of denitrifiers overgrowth: Dual mechanisms for suppressing denitrifiers while stimulating anammox bacteria in anammox-denitrification systems

2025-06-21
Xiao Ma , Jibo Xiao , Shuyi Chu +2 more | Journal of Water Process Engineering

High enrichment of heterotrophic nitrification-aerobic denitrification bacterial community achieved by shortening anoxic feeding duration in the sequencing batch reactor: feeding mode effect and mechanism

2025-06-20
Yuan Sui , You‐Wei Cui , Hui-Juan Yan +1 more | Journal of Environmental Management

System characteristics of integrated continuous flow simultaneous partial Nitrification, Anammox and Denitrification (SNAD) for NH4+-rich wastewater: performance, sludge evolution, metagenomic sequencing analysis

2025-06-19
Pengfei Yu , Ding Wang , Xing-guan Ma +7 more | Environmental Research

Metagenomic and metabolomic insights into microalgal-bacterial symbiosis under low carbon-to-nitrogen ratios

2025-06-19
Jiao-Yang Tian , Jingang Hu , Xiong Yi +5 more | Bioresource Technology

Insight into the roles of endogenous signaling molecules on aerobic granular sludge in ammonium nitrogen removal

2025-06-19
Lilong Yan , Yue Jiao , Xin Wang +4 more | Journal of Water Process Engineering

Biochar-enhanced bioreactors for agricultural nitrogen mitigation

2025-06-19
Jason Andras , Rachel L. Rubin , William Rodriguez-Reillo +3 more | Journal of Environmental Management
Excess nitrogen from agricultural, urban, and wastewater sources is a major contributor to eutrophication and water quality degradation, necessitating effective mitigation strategies. This study evaluates the effectiveness of woodchip-biochar bioreactors … Excess nitrogen from agricultural, urban, and wastewater sources is a major contributor to eutrophication and water quality degradation, necessitating effective mitigation strategies. This study evaluates the effectiveness of woodchip-biochar bioreactors in reducing nitrogen loads in agricultural drainage ditches. Biochar, a highly porous and recalcitrant form of charcoal, was incorporated alongside woodchips due to its known capacity to enhance microbial activity and nutrient retention. Three field-scale bioreactors, composed of a 50:50 volumetric mix of woodchips and biochar, were installed in experimental ditches, with three control ditches left untreated. Over an 18-month monitoring period, nitrate concentrations in bioreactor pore water were reduced by an average of 87 % compared to control ditches, suggesting that denitrification - a microbial process converting nitrate to nitrogen gas in low-oxygen conditions - played a dominant role. Biochar amendment enhanced microbial habitat, improved pH buffering, and increased nutrient retention, fostering conditions favorable for denitrification. Prokaryotic amplicon sequencing revealed a distinct microbial community structure in biochar-amended bioreactors, with enrichment of denitrifying taxa and elevated functional potential for nitrogen removal. While transient increases in ammonia and dissolved organic carbon were observed post-installation, these effects did not extend beyond the bioreactor pore water and diminished over time. These findings underscore the denitrifying potential of bioreactors in general, while highlighting the value of biochar as a strategic enhancement to traditional woodchip systems, supporting their adoption as a scalable, cost-effective strategy for reducing nitrogen pollution in agricultural watersheds.

Efficient and stable removal of organic matter, nitrogen and phosphorus from swine manure digestate by coupling high-rate activated sludge and single-stage partial nitritation/anammox-hydroxyapatite processes

2025-06-19
Yunzhi Qian , Shilong He , Yan Guo +4 more | Bioresource Technology
Organic matter stress restricts the efficiency and broader applicability of anammox process for high-nutrient digestate treatment. A high-rate activated sludge (HRAS) process coupled a single-stage partial nitritation/anammox-hydroxyapatite (PN/A-HAP) process was … Organic matter stress restricts the efficiency and broader applicability of anammox process for high-nutrient digestate treatment. A high-rate activated sludge (HRAS) process coupled a single-stage partial nitritation/anammox-hydroxyapatite (PN/A-HAP) process was developed to treat swine manure digestate. The coupled processes achieved stable removal efficiencies of 92 % (N), 63 % (P), and 66 % (chemical oxygen demand, COD), respectively. The HRAS process reduced the five-day biological oxygen demand/COD ratio to 0.31, effectively mitigating the organic stress of anammox process. The synergistic effect of HAP crystallization and heterotrophic bacterial growth induced structural fragmentation of PN/A-HAP granules. The HAP microcrystals in fragmented sludge (<100 μm) function as nucleation cores, driving PN/A-HAP granules reformation. Ca. Kuenenia dominated in the PN/A-HAP microbial community and demonstrated a positive correlation with the saturation index of HAP. This study offers a significant reference for the implementation of the HRAS-PN/A HAP process aimed at achieving COD, N, and P removal.

Evaluating the effects of aeration intermittency on treatment performance and the granule microbiome in continuous-flow aerobic granular sludge systems

2025-06-19
Nicoly Dal Santo Svierzoski , Antonio Castellano‐Hinojosa , Manuel J. Gallardo-Altamirano +3 more | Journal of environmental chemical engineering

Microbiome composition and functional potential of aerobic granular sludge in full-scale wastewater treatment plant during long-term operation

2025-06-19
Piotr Jachimowicz , Sławomir Okoński , Agnieszka Cydzik‐Kwiatkowska | Journal of environmental chemical engineering

Investigation of the cold-adapted membrane-aerated biofilm reactor: Performance analysis and community dynamics characterization

2025-06-19
Yi Li , Wenjuan Zhao , Qingyao Wang +5 more | Chemical Engineering Journal

Exploring the Effects of Fillers and Cultivation Conditions on Microbial-Algal Biofilm Formation and Cattle Wastewater Treatment Efficiency

2025-06-19
Wenchen Zhang , Lei Wu , Ming Li +4 more | Water
With the rapid development of the livestock farming industry, the treatment of livestock farming wastewater has become increasingly important. The microbial-algal biofilm method has gained widespread attention for cattle wastewater … With the rapid development of the livestock farming industry, the treatment of livestock farming wastewater has become increasingly important. The microbial-algal biofilm method has gained widespread attention for cattle wastewater treatment owing to its non-toxic nature, resistance to shock loading, and high treatment efficiency. In this study, three types of substrates—polyurethane sponge, ceramic material, and moving bed biofilm reactor media—were evaluated. The formation of biofilms was assessed through variations in chlorophyll content, microscopic observations, and measurements of biofilm dry weight and attachment rate. Biofilm characterization on the different substrates was conducted via Fourier transform infrared spectroscopy, confocal laser scanning microscopy, and scanning electron microscopy. The results demonstrated that polyurethane sponge was the most effective substrate. Furthermore, a single-factor experiment was conducted to optimize the cultivation conditions for the microbial-algal biofilms and identify the optimal parameters based on the ability of the biofilm to remove COD, TN, TP, and NH4+-N. The optimal conditions were as follows: an illumination intensity of 8000 lux, red light, a temperature of 20 °C, a pH of 7, and an aeration intensity of 8 L/min. Under these conditions, the pollutant removal rates were exceptionally high: ~73.4% for COD, 51.8% for TP, 57.0% for TN, and 75.1% for NH4+-N.

Establishing a co-culture aggregate of N-cycle bacteria to elucidate flocculation in biological wastewater treatment

2025-06-19
Laurens Parret , Kenneth Simoens , Benjamin Horemans +2 more | Applied Microbiology and Biotechnology
Biological flocculation is a complex phenomenon that is often treated as a black box. As a result, flocculation problems are usually remediated without knowledge of the exact causes. We show … Biological flocculation is a complex phenomenon that is often treated as a black box. As a result, flocculation problems are usually remediated without knowledge of the exact causes. We show that it is feasible to exploit a model (N-cycle) consortium with reduced complexity to fundamentally study bioflocculation. Strong nitrifier microcolonies were formed during oxic/anoxic cycles in sequencing batch reactors, using alginate entrapment as a cell retention system. After the release of these aggregates into suspension, macroclusters with flocs of the denitrifier were observed. These results suggest that a living model of a full-scale activated sludge floc can be built through the use of this bottom-up approach. By eliminating shifts in the microbial community, the applied experimental conditions have a more direct effect on the observations. Key Points ∙ Studying flocculation with a model consortium is feasible ∙ Alginate entrapment leads to strong microcolony formation of nitrifiers ∙ FISH by itself is not suitable to study aggregation of a coculture.

Multivariate statistic validation of pH and ORP data as control inputs for biological nitrogen removal at full scale

2025-06-19
Ángel Robles , D. Aguado , Alejandro Ríos-Mejía +3 more | Journal of Environmental Management
The objective of this study was to validate oxidation-reduction potential (ORP) and pH as input data for different advanced control strategies aimed at optimizing biological nitrogen removal under minimum aeration … The objective of this study was to validate oxidation-reduction potential (ORP) and pH as input data for different advanced control strategies aimed at optimizing biological nitrogen removal under minimum aeration energy demand. For this purpose, a statistical multivariate projection approach was applied to different control inputs calculated from on-line ORP and pH data provided by several sensors installed in different locations of a full-scale plug-flow reactor, aiming to find the strongest correlations with the data provided by nitrogen-based sensors. It has been shown that pH and ORP data can be used as control inputs for optimizing the performance of continuous nitrification, SND, and denitrification processes. Specifically, the controllers were implemented based on the derivative signals from pH and ORP instead of on their absolute values. Multivariate projection methods have displayed and evidenced strong correlations of derivative pH and ORP data with the data obtained from nitrogen-based sensors. Moreover, pH and ORP derivative signals enhance the controller's resilience to sensor faults and data biases, as these signals are less affected by these issues compared to absolute signals and signal differences from different locations along the biological process.

Functional and Genomic Evidence of L-Arginine-Dependent Bacterial Nitric Oxide Synthase Activity in Paenibacillus nitricinens sp. nov.

2025-06-19
Diego Saavedra-Tralma , Alexis Gaete , Carolina Merino Guzmán +3 more | Biology
Although nitric oxide (NO) production in bacteria has traditionally been associated with denitrification or stress responses in model or symbiotic organisms, functionally validated L-arginine-dependent nitric oxide synthase (bNOS) activity has … Although nitric oxide (NO) production in bacteria has traditionally been associated with denitrification or stress responses in model or symbiotic organisms, functionally validated L-arginine-dependent nitric oxide synthase (bNOS) activity has not been documented in free-living, non-denitrifying soil bacteria. This paper reports Paenibacillus nitricinens sp. nov., a bacterium isolated from rainforest soil capable of synthesizing NO via a bNOS under aerobic conditions. A bnos-specific PCR confirmed gene presence, while whole-genome sequencing (6.7 Mb, 43.79% GC) revealed two nitrogen metabolism pathways, including a bnos-like gene. dDDH (<70%) and ANI (<95%) values with related Paenibacillus strains support the delineation of this isolate as a distinct species. Extracellular and intracellular NO measurements under aerobic conditions showed a dose-dependent response, with detectable production at 0.1 µM L-arginine and saturation at 100 µM. The addition of L-NAME reduced NO formation, confirming enzymatic mediation. The genomic identification of a bnos-like gene strongly supports the presence of a functional pathway. The absence of canonical nitric oxide reductase (Nor) genes or other typical denitrification-related enzymes reinforces that NO production arises from an alternative, intracellular enzymatic mechanism rather than classical denitrification. Consequently, P. nitricinens expands the known repertoire of microbial NO synthesis and suggests a previously overlooked source of NO flux in well-aerated soils.

Constructing Periphytic Biofilms at the Soil–Water Interface for In Situ Control of Agricultural Surplus Phosphorus Pollution

2025-06-18
Ying Xu , Mengning Gao , Pengfei Sun +3 more | ACS ES&T Engineering

Achromobacter sp. JWJ-09 based on methanol co-metabolism efficiently enhanced the degradation of PAHs in coking wastewater and domestic sewage using activated sludge

2025-06-18
Shixin Jie , Jiangping Han , Shengwen Jia +2 more | Journal of Water Process Engineering

Photosynthetically fixed carbon neutralizes nitrous oxide and methane emissions for a carbon-negative algal-bacterial aerobic granular sludge process

2025-06-18
Jixiang Wang , Zejiao Li , Zhengwen Li +7 more | Journal of Water Process Engineering

Structure of a methanogenic granular sludge from an industrial lagoon digester determined by different microscopies

2025-06-18
Lorena Cáceres , Patricia L. Sarmiento , María Díaz‐González +1 more | Bioresource Technology Reports

Adaptation of pilot-scale one-stage partial nitritation and anammox process to kitchen waste digestion liquid and mature landfill leachate

2025-06-17
Rui Du , Guanbin Li , R. Zhao +7 more | Bioresource Technology

Optimization of nitrogen removal through an intelligent automated operational strategy based on real-time process simulation in an A2O membrane bioreactor

2025-06-17
Hyuck Kwon , Yuchan Park , Seon-Ju Kim +2 more | Journal of Environmental Management

Research progress on nitrogen‐removal characteristics and mechanisms in salt‐tolerant microorganisms

2025-06-17
Peter Liu , Tengxia He , Mengping Chen +4 more | Biological reviews/Biological reviews of the Cambridge Philosophical Society
ABSTRACT Nitrogen pollution in wastewater from industrial effluents contains various substances, including salts and organic matter, that pose potential threats to aquatic ecosystems and human health. Denitrification microorganisms therefore play … ABSTRACT Nitrogen pollution in wastewater from industrial effluents contains various substances, including salts and organic matter, that pose potential threats to aquatic ecosystems and human health. Denitrification microorganisms therefore play crucial roles in nitrogen bioremediation. This review focuses on salt‐tolerant denitrification microorganisms, including their definition and classification. The effects of salinity on three different biological nitrogen‐removal processes – nitrification–denitrification, anaerobic ammoxidation, and heterotrophic nitrification–aerobic denitrification – are systematically reviewed from the perspective of microbial communities and their practical applications in wastewater treatment. The salt‐tolerance mechanisms of denitrifying microorganisms are clarified based on the relevant genes, synthesis of compatible intracellular solutes, ion transport, and extracellular polymeric substances involved. A comprehensive understanding of the mechanisms underlying salt tolerance in denitrifying microorganisms is essential for accelerating nitrogen‐removal rate in saline conditions and could contribute to the development of effective strategies for microbial removal of nitrogen in saline environments.

Elucidating the denitrification potential driven by sulfide for treating nitrate nitrogen rich wastewater

2025-06-17
H.P. Wang , Xiaoran Sun , Zhijuan Tian +3 more | Journal of Water Process Engineering

Methodology Discrepancy and Data Comparability of Greenhouse Gas Monitoring from Water Resource Recovery Facilities

2025-06-17
Yuqing Yan , Cuihong Song , Jun‐Jie Zhu +3 more | Environmental Science & Technology
Wastewater is a major source of methane (CH4) and nitrous oxide (N2O), highlighting the need for accurate monitoring to develop accurate inventories and effective mitigation strategies. This study systematically evaluates … Wastewater is a major source of methane (CH4) and nitrous oxide (N2O), highlighting the need for accurate monitoring to develop accurate inventories and effective mitigation strategies. This study systematically evaluates current measurement methodologies, emphasizing significant variability across different techniques that contribute to reporting discrepancies. Bottom-up approaches, such as flux chambers and in situ liquid sensors, dominate unit-level data collection, while emerging top-down methods provide plant-level-integrated estimates. No inherent bias was identified across methodologies, but the choice of techniques was influenced by the treatment processes and operational conditions. When multiple methods were applied at the same site, calibrations were needed between emission factors derived from the dissolved and gaseous concentrations. Data scarcity hinders inventory building for sewers, distributed systems, and facility-level analysis. This study offers a comprehensive review of current monitoring practices and proposes a framework to address the data gaps and inconsistencies. By advocating for harmonized methodologies, the framework seeks to enhance data comparability and reliability by integrating available approaches while promoting more comprehensive data reporting to facilitate meta-analyses and cross-contextual evaluations.

Hexachlorobutadiene pollution affected soil ammonia oxidation processes through affecting ammonia oxidizing microorganisms

2025-06-16
Fangfang Liu , Jing Chen , Y. Jun Xu +5 more | Ecotoxicology and Environmental Safety

Magnetite-Augmented Sulfur-Siderite Autotrophic Denitrification: Deep Nitrogen Removal at Ultra-Low HRT from Lab to Pilot Scale

2025-06-16
Jiale Sun , Haoyong Li , Dong He +5 more | Water Research

Effects of temperature on biofilm formation and resource recovery during anoxyphototrophic treatment of fuel‐synthesis wastewater

2025-06-16
S. Shaikh , Soumia Gasmi , A. S. Luyt +2 more | Journal of Chemical Technology & Biotechnology
Abstract BACKGROUND Fuel‐synthesis wastewater (FSW), a byproduct of the Fischer‐Tropsch process, requiring efficient treatment and resource recovery strategies. This study aimed to optimize temperature conditions for purple non‐sulfur bacteria (PNSB) … Abstract BACKGROUND Fuel‐synthesis wastewater (FSW), a byproduct of the Fischer‐Tropsch process, requiring efficient treatment and resource recovery strategies. This study aimed to optimize temperature conditions for purple non‐sulfur bacteria (PNSB) biofilm formation and bioproduct recovery while simultaneously treating FSW. Experiments were conducted in biofilm photobioreactors operated at 30 °C, 35 °C, and 45 °C under illuminated anaerobic conditions. The study evaluated PNSB growth, wastewater treatment efficiency, and the yields of bioproducts, including polyhydroxybutyrate (PHB), single cell protein (SCP), lipids, carbohydrates and pigments. RESULTS No PNSB growth was observed at 45 °C, while the highest suspended growth occurred at 35 °C and biofilm growth at 30 °C. Biofilm formation significantly increased PHB accumulation (17%) compared to suspended growth (4.3%–7.4%), highlighting the efficiency of biofilm‐based cultivation. Temperature had a minimal effect on PHB composition but influenced its crystallinity and morphology. The protein content remained consistent across conditions, while lipids increased with temperature. CONCLUSION Temperature selection between 30 °C and 35 °C significantly influences biofilm versus suspended biomass ratios and differentially affects bioproduct yields. Biofilm cultivation is preferable for maximizing PHB recovery, indicating potential for sustainable resource recovery and wastewater treatment strategies, particularly in tropical regions where external temperature regulation may be unnecessary. © 2025 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry (SCI).

Integrated approach for waste activated sludge stabilization under ultra-short solids retention time

2025-06-16
Xi Lu , Xiaotong Cen , Zhiqiang Zuo +5 more | Bioresource Technology

Accelerated Start-Up and Microbial Community Using Novel Plant-Based Waste Biofilter Media for Treatment of Real Domestic Wastewater via Simultaneous Nitrification and Denitrification

2025-06-16
Zhang Zhan Loh , Achmad Syafiuddin , Nur Syamimi Zaidi +4 more | ACS ES&T Water

Temperature-Dependent Regulation of Denitrification Intermediates in High-Temperature Ecosystems

2025-06-16
Liyuan Ma , Liuqin Huang , Yuan-Guo Xie +7 more | Environmental Science & Technology
Incomplete denitrification generates diverse nitrogen intermediates (e.g., NO2-, N2O), which may reshape nitrogen redox dynamics and modulate ecosystem functions. While prevalent in high-temperature ecosystems, the mechanisms regulating temperature-dependent denitrification remain … Incomplete denitrification generates diverse nitrogen intermediates (e.g., NO2-, N2O), which may reshape nitrogen redox dynamics and modulate ecosystem functions. While prevalent in high-temperature ecosystems, the mechanisms regulating temperature-dependent denitrification remain unclear. To address this gap, we used hot springs with different temperatures (ranging from 37 to 75 °C) as representative environments and conducted enrichment cultures with both in situ hot spring water and defined media with varying acetate/NO3- ratios. Denitrification product profiles shifted systematically with temperature: NO2- dominated above 60 °C, NO2- and N2O at 55 °C, and N2 below 45 °C. Multiomics analyses revealed temperature-driven succession of dominant denitrifiers, with microorganisms affiliated with Thermus (>60 °C), Tepidimonas (55 °C), and Thauera/Uliginosibacterium (<45 °C). Denitrification core and accessory gene expressions showed temperature-specific patterns associated with intermediate formation. High expression of upstream core genes (e.g., narG) and limited expression of accessory genes in Thermus spp. promote incomplete denitrification at high temperatures, while low-temperature communities upregulated complementary pathways (e.g., nosRD with nosZ in Thauera spp.) for complete denitrification. Division of metabolic labor appears to be more important in denitrifying communities at high temperatures, where dominant denitrifiers perform incomplete denitrification and downstream intermediates are reduced by minor species (e.g., N2O reduction). These findings improve understanding of denitrification in thermally dynamic environments and reveal mechanisms underlying its temperature-dependent regulation.

Metagenomics reveal the mechanisms of integrated heterotrophic and sulfur autotrophic denitrification (HSAD) using PBAT/starch as carbon source

2025-06-16
Yale Deng , Junchi Li , Mohammad J. Taherzadeh +6 more | Journal of Hazardous Materials

Molecular Characterization of a Transcriptional Regulator GntR for Gluconate Metabolism in Industrial 2-Ketogluconate Producer Pseudomonas plecoglossicida JUIM01

2025-06-15
Mengjian Qu , Lulu Li , Xinyi Zan +3 more | Microorganisms
The GntR is a transcriptional regulator generally known as a gluconate-operon repressor to specifically regulate the transportation and phosphorylation of gluconate. In the present study we report the cloning of … The GntR is a transcriptional regulator generally known as a gluconate-operon repressor to specifically regulate the transportation and phosphorylation of gluconate. In the present study we report the cloning of the GntR-encoding gene of the industrial 2-ketogluconate (2KGA)-producer Pseudomonas plecoglossicida JUIM01, which is involved in the regulation of gluconate metabolism, along with the identification of some of its target genes and its operator sequence. GntR is a 36.36-kDa cytoplasmic and hydrophobic DNA-binding transcriptional regulator belonging to the LacI family. The knockout of gntR resulted in the significant upregulation of the transcription of the gluconate kinase gene gntK and, to a lesser extent, the permease gene gntP, as well as downregulation of genes involved in glucose uptake (oprB-1, gltB, gltF, gltG, and gltK) and those involved in 2-ketogluconate (2KGA) transport (kguT) and catabolism (kguE, kguK, and kguD). These results indicated that GntR positively regulated glucose and 2KGA transport and catabolism, while negatively affecting GntP-mediated gluconate uptake and gluconate phosphorylation by GntK. Electrophoretic mobility shift assay (EMSA) and DNase I footprinting analyses confirmed that GntR interacted with operator sequences in the divergent promoter regions of gntK and gntP, as well as in the gntR promoter region. A putative operator sequence (consensus 5′-AG-N2-AGCGCT-N-TCT-3′) was identified. These data suggest that GntR positively regulates genes involved in glucose uptake/transport and 2KGA transport/catabolism, while repressing its own expression as well as that of genes involved in gluconate transport/catabolism. These findings not only elucidate the regulation of GntR and its target genes in P. plecoglossicida, but also provide valuable insights for optimizing industrial 2KGA production.

Niche differentiation of anammox genera with sludge blanket expansion in anammox expanded granular sludge bed induced by short hydraulic retention time condition

2025-06-15
Xin Wang , Yijing Zhu , Changqing Liu +4 more | Bioresource Technology

Machine Learning-Based Optimization of Enhanced Nitrogen Removal in a Full-Scale Urban Wastewater Treatment Plant with Ecological Combination Ponds

2025-06-14
Junhua Yun , Yang Yu , Chenliang Tao +6 more | Water Research

Simultaneous removal of humic acid and nitrate by combining micro-electrolysis and autotrophic denitrification

2025-06-13
Guangxin Zhou , Wei Xing , Kexin Tian +2 more | Frontiers of Environmental Science & Engineering

Enhanced nitrogen removal via simultaneous nitrification-denitrification (SND) and Feammox in a magnetic zeolite modified intermittently aerated sequential biological reactor

2025-06-13
Min Pan , Tao Jiang , Zihan Wang +3 more | Frontiers of Environmental Science & Engineering

Biohydrogen production from water hyacinth–A review of pretreatment, production, and purification processes

2025-06-13
Huy Hoang Phan Quang , Huu Quynh Anh Le , Phan Khanh Thinh Nguyen | Biomass and Bioenergy

Mining robust in situ phosphorus-accumulating organisms via single-cell RACS-Culture for rational ecosystem engineering

2025-06-01
Xiaoyan Jing , Yanhai Gong , Yishang Ren +7 more | Water Research