Search

The California current system (CCS) hosts one of the largest oxygen minimum zones (OMZs) in the world: the Eastern North Pacific (ENP) OMZ, which is dissociated into a subtropical and tropical region (i.e., the ESTNP and ETNP). In the modern ENP OMZ, bioavailable nitrogen (N) is lost via denitrification and anaerobic ammonium oxidation (anammox). Even so, paleo-reconstructions of N-loss have focused solely on denitrification. Fluctuations in bulk sedimentary δ15N over glacial-interglacial cycles have been interpreted to reflect variations in denitrification rates in response to ETNP OMZ intensity changes. This δ15N signal is thought to be transported northwards to the ESTNP OMZ. Here, we present the first CCS sedimentary record of ladderane lipids, biomarkers for anammox, located within the ESTNP OMZ (32°N; 118°W). Over the last two glacial terminations (~160 cal ka BP), ladderane concentrations were analysed in combination with the index of ladderanes with five cyclobutane moieties (NL5), short-chain (SC) ladderane degradation products, and productivity proxies. This shows that: 1) ladderanes derived from anammox bacteria living within the ESTNP OMZ water column; 2) ladderanes were continuously present, with relatively high concentrations during both glacial- and interglacial-periods, showcasing the ESTNP OMZ must have retained an anoxic core in which N-loss occurred; and 3) anammox abundance appears to have been driven both by OM-remineralization and advection changes, which regulated nutrient and oxygen levels. Our study shows that anammox was an important feature in the CCS and provides a more holistic picture of N-loss dynamics and the development of the ESTNP OMZ over glacial-interglacial cycles. Lastly, ladderanes were also detected in 160-500 cal ka BP sediments (15.7-37.5 mbsf; analysed at a low temporal resolution), highlighting their potential as anammox biomarkers in relatively deeper buried sediments for future studies. [ABSTRACT FROM AUTHOR]

Anaerobic ammonium oxidation (anammox) has shown success in past years for the treatment of municipal and industrial wastewater containing inorganic nutrients (i.e., nitrogen). However, the increase in polycyclic aromatic hydrocarbon (PAH)-contaminated matrices calls for new strategies for efficient and environmentally sustainable remediation. Therefore, the present review examined the literature on the connection between the anammox process and PAHs using VOSviewer to shed light on the mechanisms involved during PAH biodegradation and the key factors affecting anammox bacteria. The scientific literature thoroughly discussed here shows that PAHs can be involved in nitrogen removal by acting as electron donors, and their presence does not adversely affect the anammox bacteria. Anammox activity can be improved by regulating the operating parameters (e.g., organic load, dissolved oxygen, carbon-to-nitrogen ratio) and external supplementation (i.e., calcium nitrate) that promote changes in the microbial community (e.g., Candidatus Jettenia), favoring PAH degradation. The onset of a synergistic dissimilatory nitrate reduction to ammonium and partial denitrification can be beneficial for PAH and nitrogen removal. [ABSTRACT FROM AUTHOR]

Realizing the smallest nitrogen loss is a challenge in the nitrate reduction process. Dissimilatory nitrate reduction to ammonium (DNRA) and nitrate assimilation play crucial roles in nitrogen retention. In this study, the effects of the carbon source, C/N ratio, pH, and dissolved oxygen on the multiple nitrate reduction pathways conducted by Pseudomonas putida Y-9 are explored. Strain Y-9 efficiently removed nitrate (up to 89.79%) with glucose as the sole carbon source, and the nitrogen loss in this system was 15.43%. The total nitrogen decrease and ammonium accumulation at a C/N ratio of 9 were lower than that at 12 and higher than that at 15, respectively (P < 0.05). Besides, neutral and alkaline conditions (pH 7–9) favored nitrate reduction. Largest nitrate removal (81.78%) and minimum nitrogen loss (10.63%) were observed at pH 7. The nitrate removal and ammonium production efficiencies of strain Y-9 increased due to an increased shaking speed. The expression patterns of nirBD (the gene that controls nitrate assimilation and DNRA) in strain Y-9 were similar to ammonium patterns of the tested incubation conditions. In summary, the following conditions facilitated nitrate assimilation and DNRA by strain Y-9, while reducing the denitrification: glucose as the carbon source, a C/N ratio of 9, a pH of 7, and a shaking speed of 150 rpm. Under these conditions, nitrate removal was substantial, and nitrogen loss from the system was minimal. [ABSTRACT FROM AUTHOR]

A new bacterium capable of heterotrophic nitrogen removal was isolated and identified as Oligella sp. XS68. The strain exhibited efficient heterotrophic nitrogen removal capabilities, with a low accumulation of nitrification products. Single-factor experiments indicated that efficient nitrogen removal and growth of the strain XS68 occurred with sodium succinate as the carbon source, C/N ratio 15, pH 6.0-9.0, temperature 30-37 °C, and shaking speed 160-200 rpm. The removal efficiency of ammonium nitrogen could achieve 98 % within 96 h when the initial nitrogen concentration was 421.3 mg L-1. These findings demonstrate that XS68 is a promising candidate for nitrogen removal in wastewater treatments. [ABSTRACT FROM AUTHOR]

• Denitrification alone does not govern N removal in woodchip and coconut husk bioreactors. • Substantial N removal can be achieved via the anammox pathway. • Relative contributions of denitrification and anammox vary between media types used. • Anammox becomes more dominant when denitrification is carbon limited. Denitrification has been considered the main pathway converting nitrate (NO 3 –) to dinitrogen gas (N 2) in denitrifying bioreactors. Here, the importance of an alternative nitrogen (N) removal process, namely anaerobic ammonium oxidation (anammox), was assessed by monitoring the removal of N species from partially nitrified municipal wastewater passing through fifteen mesocosm scale (∼700 L) bioreactors containing woodchip, coconut husk or gravel during their initial and eighth year of operation. Additionally, lab experiments using a 15N isotope-pairing technique were performed to partition production of N 2 to these different microbial processes. The effective removal of both NO 3 – and ammonium (NH 4 +) and the formation of hybrid N 2 (i.e. 29N 2) observed in this study demonstrated that, along with denitrification, anammox was an effective pathway for N removal when both NO 3 – and NH 4 + were present. Anammox removal rates ranged from 0.6 to 3.8 g N per m3 per day, while denitrification rates ranged from 0.7 to 2.6 g N per m3 per day. The contributions of anammox to N removal was dependent on media, with anammox becoming more dominant in bioreactors where denitrification was carbon limited. Designing denitrifying bioreactors to support both denitrification and anammox expands the utility of these passive approaches for improving treatment of wastewater. [ABSTRACT FROM AUTHOR]

Thiocyanate (SCN−)-based autotrophic denitrification (AD) has recently been demonstrated as a promising technology that could be integrated with anaerobic ammonium oxidation (Anammox) to achieve simultaneous removal of nitrogen and SCN−. However, there is still a lack of a complete SCN−-based AD model, and the potential microbial competition/synergy between AD bacteria and Anammox bacteria under different operating conditions remains unknown, which significantly hinders the possible application of coupling SCN−-based AD with Anammox. To this end, a complete SCN−-based AD model was firstly developed and reliably calibrated/validated using experimental datasets. The obtained SCN−-based AD model was then integrated with the well-established Anammox model and satisfactorily verified with experimental data from a system coupling AD with Anammox. The integrated model was lastly applied to investigate the impacts of influent NH 4 +-N/NO 2 −-N ratio and SCN− concentration on the steady-state microbial composition as well as the removal of nitrogen and SCN−. The results showed that the NH 4 +-N/NO 2 −-N ratio in the presence of a certain SCN− level should be controlled at a proper value so that the maximum synergy between AD bacteria and Anammox bacteria could be achieved while their competition for NO 2 − would be minimized. For the simultaneous maximum removal (>95%) of nitrogen and SCN−, there existed a negative relationship between the influent SCN− concentration and the optimal NH 4 +-N/NO 2 −-N ratio needed. Image 1 • A complete thiocyanate-based autotrophic denitrification (AD) model was developed. • Thiocyanate-based AD model was evaluated with integration of Anammox model. • Relationship between thiocyanate and NH 4 +-N/NO 2 −-N for maximum removal was studied. High-level (>95%) simultaneous removal of nitrogen and thiocyanate could be achieved through combining thiocyanate-based autotrophic denitrification and Anammox. [ABSTRACT FROM AUTHOR]

A dynamic analysis approach for determining nitrite production and consumption rates was established to systematically investigate the characteristics of nitrogen transformation and N 2 O emission of the completely autotrophic nitrogen removal over nitrite (CANON) process coupled with denitrification using a sequencing batch biofilm reactor (SBBR). The results indicate that anaerobic ammonium-oxidizing bacteria was not inhibited significantly by low C/N ratios. There were no obvious differences in the nitrite production rate, nitrite consumption rate or nitrogen removal among reactors operated with C/N ratios of 0, 0.67 and 1.00, which suggested that the certain carbon source did not significantly affect the nitrite conversion and nitrogen removal in the process. More than 60% of total N 2 O emission is generated during the initial phase of each period in the SBBR. More than 94.5% of N 2 O was generated by NO 2 −-N consumption via denitrification in the process. Interestingly, total N 2 O production drops by 16.7%, when the C/N ratio increases from 0 to 1. This phenomenon may be caused by the inhibition of N 2 O production via AOB denitrification. Therefore, an appropriate carbon source (C/N = 1.00) has the beneficial effect of reducing N 2 O emission by CANON coupled with denitrification. The results of this study provide an important empirical foundation for the mitigation of N 2 O emission in the CANON process coupled with denitrification. Image 1 • N conversion and N 2 O emission were investigated in a CANON coupled with DN process. • AOB and AnAOB were not inhibited significantly by low C/N ratios. • Low C/N ratios did not evidently affect nitrite conversion and nitrogen removal. • More than 94.5% of N 2 O was generated by NO 2 −-N consumption via denitrification. • The C/N ratio should be maintained at 1.00 for the N 2 O emission reduction. [ABSTRACT FROM AUTHOR]

Dissimilatory nitrate reduction to ammonium (DNRA), denitrification, anaerobic ammonium oxidation (anammox) and biological N2 fixation (BNF) can influence the nitrogen (N) use efficiency of rice production. Whilst the effect of N application on BNF is known, little is known about its effect on NO3 - partitioning between DNRA, denitrification and anammox. Here, we investigated the effect of N application on DNRA, denitrification, anammox and BNF, and on the abundance of relevant genes in three paddy soils in Australia. Rice was grown in the glasshouse with (150 kg N ha-1 ) and without N-fertiliser for 75 days, and the rhizosphere and bulk soils were collected separately for laboratory incubation and quantitative PCR analysis. Nitrogen application reduced DNRA rates by >16% in all the soils regardless of the rhizospheric zone but it did not affect the nrfA gene abundance. Without N, the amount and proportion of NO3 - reduced by DNRA (0.42-0.52 µg g-1 soil day-1 , 45-55%) was similar or higher than that by denitrification. However, with N the amount of NO3 - reduced by DNRA (0.32-0.40 µg g-1 soil day-1 ) was 40-50% lower than the NO3 - reduced by denitrification. Denitrification loss increased by >20% with N addition, and was affected by the rhizospheric zones. Nitrogen loss was minimal through anammox, while BNF added 0.02-0.25 µg N g-1 soil day-1. We found that DNRA plays significant positive role in paddy soil N retention as it accounts for up to 55% of the total NO3 - reduction, but this is reduced by N application. [ABSTRACT FROM AUTHOR]

The fate of the enormous amount of reactive nitrogen released to the environment by human activities in India is unknown. Here we show occurrence of seasonal stratification and generally low concentrations of dissolved inorganic combined nitrogen, and high molecular nitrogen (N2) to argon ratio, thus suggesting seasonal loss to N2 in anoxic hypolimnia of several dam-reservoirs. However, 15N-experiments yielded low rates of denitrification, anaerobic ammonium oxidation and dissimilatory nitrate reduction to ammonium--except in the presence of methane (CH4) that caused ~12-fold increase in denitrification. While nitrite-dependent anaerobic methanotrophs belonging to the NC10 phylum were present, previously considered aerobic methanotrophs were far more abundant (up to 13.9%) in anoxic hypolimnion. Methane accumulation in anoxic freshwater systems seems to facilitate rapid loss of reactive nitrogen, with generally low production of nitrous oxide (N2O), through widespread coupling between methanotrophy and denitrification, potentially mitigating eutrophication and emissions of CH4 and N2O to the atmosphere. [ABSTRACT FROM AUTHOR]

Mechanisms through which microorganisms are impacted by surface application of ground cover and nutrient source in organic orchard management are not fully understood. Twelve ground cover (compost, wood chips, paper mulch, or mow-and-blow) by fertilizer (poultry litter, organic commercial, or a no-fertilizer control) treatment combinations were applied annually in April beginning in 2006, with soil collected in March 2007 and 2013 to determine the 1-year and 7-year effects of treatments on soil chemical and biological properties. Organic matter (OM) increased through time regardless of ground cover treatment averaged across fertilizers, with the greatest increase occurring with compost addition. Soil water content, microbial biomass N, ammonium-N, and nitrate-N were greater in 2013 than in 2007 at the 0–10 cm depth. Denaturing gradient gel electrophoresis analysis of denitrifying ( nirK) communities revealed that fertilizers did not have a significant main effect or interaction with ground covers. Greater nirK richness and diversity coincided with clustering of the nirK community composition within compost treatments, and greater dissolved organic carbon concentrations with compost compared to wood chip or mow-and-blow treatments in 2007. By 2013 nirK communities in wood chip and compost ground covers tended to cluster together. Furthermore, soil nirK richness increased significantly from 2007 to 2013 in compost and wood chip treatments and was greatest in 2013 under those two ground covers. Diversity with wood chip addition increased from among the least in 2007 to among the greatest in 2013. Greater richness and diversity and community composition in the nirK community within a year of compost additions and gradually over time with wood chip addition indicate potential for enhanced denitrification in low OM, organic apple orchard soil receiving compost and wood chips mulches. [ABSTRACT FROM AUTHOR]

High organic loadings to constructed wetlands can result in water quality issues such as low dissolved oxygen and high ammonium concentrations, with artificial aeration a potential mitigation option. This study compared baseline (no aeration – NA), continuous aeration (CA), and intermittent aeration (IA) conditions to improve water quality in a tertiary treatment free water surface constructed wetland (FWS CW) with night time hypoxia/anoxia, and high nutrient concentrations. The response variables included dissolved oxygen (DO), total nitrogen (TN), ammonium nitrogen (NH 4 +-N), nitrate nitrogen (NO 3 −-N), total phosphorus (TP), phosphate (PO 4 3–-P), and dissolved organic carbon (DOC). In situ aeration and monitoring was performed from April to June 2021 in a large, field-scale FWS CW, the Laratinga wetlands Mount Barker, South Australia. The results demonstrated that DO increased by an average 2.11 mg L−1 from NA to CA during the night and 1.26 mg L−1 and 1.84 mg L−1 from NA to IA during the night and day respectively when averaging over the basins. The C/N ratio was very low and there was no significant influence of DO on DOC concentrations. There was no significant difference in TN concentrations with the application of aeration aside from a decrease in the channel at night from NA to IA, and an increase in NH 4 +-N resulted under IA compared with NA in Basin 1 and 2 during the day. This implies that the N loadings exceeded the wetland's ability to complete nutrient conversions at a rate that aligns with input rate. The concentrations of NO 3 −-N increased at night under CA and IA treatments suggesting that some nitrification was promoted, or there was inhibition of dissimilatory nitrate reduction to ammonium. The concentrations of TP and PO 4 3–-P significantly increased with the aeration compared with no aeration, however there was no difference between the aeration treatments. This suggested that increased sediment resuspension during aeration increased P in the water. There was no change in DOC with the application of aeration. Overall, the DO increased with aeration application and may be able to better support the wetland ecology; however, the Laratinga wetland is overloaded and the capacity of the wetland to effectively transform and remove nutrients is inhibited, even with the application of artificial aeration. • Dissolved oxygen increased with the application of continuous and intermittent aeration. • There was no change in total nitrogen with aeration and ammonium levels remained high. • There was a small increase in nitrate, and total and soluble phosphorus with aeration. • Despite near-neutral pH values, unionised ammonia was calculated to be at toxic levels. • Using aeration to manage systems with high nutrient loadings is challenging. [ABSTRACT FROM AUTHOR]

Ammonium (NH 4 +) enrichment of riverbank filtration (RBF) systems is gaining popularity. However, most previous research has concentrated on NO 3 − removal efficiencies, while the mechanisms of NH 4 + enrichment remain unknown. A nitrogen biogeochemical process model was developed for the quantitative analysis of NH 4 + enrichment in the Kaladian well field in northwest Songyuan City, NE China. Data from laboratory experiments and in-situ monitoring were used to determine initial values and calibrate the thermodynamic/kinetic parameters representing nitrogen (N) biogeochemical reactions. (1) The NO 3 − from river was subjected to denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA) within 10–14 m of the shore, whereas the NH 4 + in groundwater was caused by DNRA, organic nitrogen mineralization (MIN), and mixing with laterally recharged high NH 4 + groundwater. (2) DNF and DNRA were regulated by hydrodynamic processes, with the ranges of these processes being more significant in the wet season due to a higher hydraulic gradient. MIN occurred widely throughout the water flow path, with temperature primarily controlling the rates of the three reactions. (3) DNRA activity was relatively higher in the wet season when the water temperature was higher within 10–14 m of the shore. In the wet season, DNRA contributed 25%–30% to NO 3 − reduction, which was higher than in the dry season (5%–10%). DNRA contributed at least 40% and 15% to NH 4 + enrichment in the wet and dry seasons, respectively. (4). Organic N in media gradually released NH 4 + into groundwater via MIN and desorption across the entire flow path, with contributions to NH 4 + enrichment reaching 75% and 85%, respectively, in the wet and dry seasons. • Spatiotemporal variations of N biogeochemical reactions in RBF were identified. • Conditions for denitrification, DNRA, and mineralization in RBF were identified. • Simulation parameters were refined through multi-environmental N experiments. • Contributions of DNRA to NO 3 − reduction and NH 4 + enrichment were quantified. • Introduction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The coupling of Feammox and NDFO is novel and cost-effective. • The comparison between this process and other denitrification technologies is summarized. • The main factors affecting the coupling process and the research of the process are analyzed. • The transformation forms of iron and nitrogen are two key issues in the coupling process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Continuous aeration in membrane-aerated biofilms resulted in full nitrification. • Intermittent aeration suppressed nitrite oxidation and supported anammox process. • Biofilm pH presented periodic upshifts with aeration switches. • Free ammonia speciation likely caused the inhibition of nitrite-oxidizing bacteria. • Heterotrophs established nitrous oxide-reduction zones under intermittent aeration. Membrane-aerated biofilm reactors (MABR) are being applied for autotrophic nitrogen removal, yet control of nitrogen turnover remains challenging in MABR counter-diffusion biofilms. In this study, we regulated microbial activities in two lab-scale MABRs by providing continuous versus intermittent aeration. Nitrogen consumption by different functional microbial groups was estimated from bulk measurements via a mass balance approach. Nitrite-oxidizing bacteria (NOB) proliferated under continuous aeration while they were significantly suppressed under intermittent aeration, and NOB suppression activated anaerobic ammonium oxidation. Nitritation performance in the MABR was studied through long-term bulk measurements and in situ biofilm microprofiles of dissolved oxygen (DO) and pH. During intermittent aeration pH effects rather than DO effects determined nitritation success, especially ammonia speciation, which serves as substrate and inhibitor in nitrification processes. Biofilm transition phases were monitored upon aeration switches. Canonical correspondence analysis suggested that the relative transition after anoxia and aeration intermittency were less decisive for biofilm performance than the relative aeration duration. Heterotrophic bacteria displayed minor denitrification rates with aeration control, but contributed to mitigation of nitrous oxide (N 2 O) emissions. N 2 O production hotspots were identified at the top of the anoxic biofilm zone under continuous aeration. Instead, under intermittent aeration an anoxic N 2 O reduction zone was established. Our observations support intermittent aeration control of MABRs as a simple strategy for energy-efficient nitrogen removal with low N 2 O emission.. [ABSTRACT FROM AUTHOR]

A combination of anaerobic ammonium oxidation (anammox) with sulfur-autotrophic denitrification is a promising alternative for complete nitrogen removal. Herein, a novel anammox coupled with sulfite-driven autotrophic denitrification (ASDAD) is firstly proposed. The influence of pH (8.5–6.5) on nitrogen removal and N 2 O emission is investigated in an anaerobic sequencing batch biofilm reactor fed with low-nitrogen wastewater containing sulfite. Long-term operation demonstrates that a maximum nitrogen removal of 94.5% occurred at a pH of 7.5 and that the contribution of autotrophic denitrification to nitrogen removal increased as the pH declined. Cyclic and batch experiments verify that anammox and sulfite-autotrophic denitrification simultaneously participates in nitrogen removal, and the stoichiometry for sulfite-driven autotrophic denitrification is firstly proposed. Furthermore, N 2 O accumulation is also highly correlated with the pH. The N 2 O emission peaks at a pH of 6.5 due to the inactivated anammox and incomplete autotrophic denitrification of nitrite at such a low pH. High-throughput sequencing reveals the coexistence of anammox (Candidatus Brocadia and Candidatus Kuenenia) and sulfur-oxidizing species (Thiobacillus). Finally, the schema for nitrogen conversion and N 2 O formation of ASDAD is elucidated based on metagenomic metabolism. This study offers a cost-effective and environment-friendly completely autotrophic nitrogen removal process for municipal wastewater with a low carbon-to-nitrogen ratio in practice. [Display omitted] • A novel anammox-sulfite autotrophic denitrification (ASDAD) process was developed. • Optimal pH for maximum nitrogen removal of ASDAD was 7.5 • N 2 O emission factor was the highest as 0.71% at a pH of 6.5 • Co-existence of C. Brocadia , C. Kuenenia and Thiobacillus promoted ASDAD. • Schema for nitrogen conversion and N 2 O formation was elucidated. [ABSTRACT FROM AUTHOR]

Agriculture has long been considered a great source of nitrogen (N) to surface waters and a major cause of eutrophication. Thus, management practices at the farm-scale have since attempted to mitigate the N losses, although often limited in tile-drained agricultural catchments, which speed up the N transport, while minimizing natural removal in the landscape. In this context, surface-flow constructed wetlands (SFWs) have been particularly implemented as an edge-of-field strategy to intercept tile drains and reduce the N loads by re-establishing ecosystems services of previously drained water ponded areas. These systems collect the incoming water volumes in basins sufficiently large to prolong the hydraulic residence time to a degree where biogeochemical processes between the water, soil, sediments, plants, macro and microorganisms can mediate the removal of N. Despite their documented suitability, great intra and inter-variability in N treatment is still observed to date. Therefore, it is essential to thoroughly investigate the driving factors behind performance of SFWs, in order to support their successful implementation according to local catchment characteristics, and ensure compliance with N removal goals. This review contextualizes the aforementioned issue, and critically evaluates the influence of hydrochemistry, hydrology and biogeochemistry in the treatment of N by SFWs. [ABSTRACT FROM AUTHOR]

The mechanisms behind nitrogen removal by the submersed macrophyte-biofilm complex in wetlands remain to be fully elucidated. This study investigated the role of Myriophyllum spicatum and the biofilm on their leaves in nitrogen removal in mesocosm experiments. 15N tracking showed that 61.9% and 30% of the 15N, respectively, was removed from the system and assimilated by the macrophyte-biofilm complex after loading with 5.4 mg L−115N labelled NH 4 + for 17 days. Nitrogen budget results showed that about 0.2%, 0.2% and 3.6% of the nitrogen were emitted as water-, HCl- and NaOH-soluble nitrogen-gas species, respectively. Bacteria (76.7–91.8%) were the predominant domain in all samples, followed by eukaryotes (8.0–23.0%), archaea and viruses. Network analyses showed that there were positive- and negative-correlative relationships among nitrogen-cycling genes and nitrifiers and denitrifiers. Our data highlight the important role of biofilm on submersed macrophytes for nitrogen removal. Image 1 • M. spicatum restoration promoted nitrogen removal in constructed wetlands (mesocosm scale). • The biofilms had a higher competitiveness for waterborne nitrogen than M. spicatum. • Bacteria were the most dominant domain, followed by eukaryotes, archaea and viruses. • There were complex interactions among nitrogen-cycling genes and genera. The biofilms had a higher competitiveness for nitrogen than M. spicatum and there were complex interactions among nitrogen-cycling genes and genera in biofilms. [ABSTRACT FROM AUTHOR]

Influence of anammox process on autotrophic denitrification was investigated in this study, during simultaneous ammonium, nitrate and sulfide treatment. Elemental sulfur production and nitrogen removal by sulfide-dependent denitrifier (S-den) and mixed culture (S-den-anammox) were compared. Accumulation of nitrite (100%) and elemental sulfur (46.3%) was achieved at pH 7.0 and 30 °C with S 2 O 3 2−/NO 3 − ratio of 1:1 by autotrophic denitrifier. Enhanced elemental sulfur production (56.5%–99.5%) by autotrophic denitrifier was obtained after coupling with anammox process. Total nitrogen removal increased to 80.5% in mixed culture reactor, which was 72.0% in anammox reactor. N 2 O emission in anammox reactor was not affected (<0.5% gaseous nitrogen) after coupling with autotrophic denitrification. Therefore, this study demonstrated enhanced elemental sulfur recovery and nitrogen removal through coupling of sulfide-dependent denitrification and anammox processes, which might be a potential technology for water eutrophication and corrosion control, and atmospheric acid rain, PM 2.5 and global warming control. Image 1 • Removal of NO 3 −, S2− and NH 4 + was achieved in sulfide-dependent DEAMOX process. • Elemental sulfur production was enhanced 26.8% after cooperation with anammox. • TN removal increased about 10% in sulfide-dependent DEAMOX reactor. • NO x was lower than 0.5% gaseous nitrogen in sulfide-dependent DEAMOX reactor. [ABSTRACT FROM AUTHOR]