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Efficient management of pollutant risks in water bodies is crucial for public health and aquatic ecosystem sustainability. However, the toxicities of pollutants, such as ammonia nitrogen (NH 3 -N), are often affected by multiple water quality factors, including the pH and water temperature. Extensive spatial and temporal variability in these factors hinders tailor-made management of risk. This study used high-frequency monitoring data collected over 1 year to evaluate the long-term NH 3 -N risk in China's aquatic ecosystems. High accuracy and interpretability were achieved by decomposing NH 3 -N risk into the contributions of key influencing factors using random forest models and Shapley Additive Explanations. Two distinct types of NH 3 -N risk hotspots were identified across 18 cities: 15 cities with high NH 3 -N concentrations and 3 cities with low environmental carrying capacity due to high pH levels or elevated water temperatures. For the former, rapid NH 3 -N abatement measures are necessary to bring NH 3 -N concentrations back below the environmental capacity. For the latter, it is recommended that NH 3 -N related industries are relocated to regions with high environmental capacities because fragile environments are not suitable for such industries. Importantly, this study investigated methods for attributing pollutant risks in the context of non-linear influencing factors, and the risk of NH 3 -N was predicted to increase by 6.1 % by the end of 2100 in the context of increasing temperatures under the SSP 2–4.5 scenario. The methodology is also adaptable and suitable for integration into global ecosystem risk management efforts to balance development and aquatic ecological sustainability. [Display omitted] • NH3-N risk management framework was built by monitoring data and a prediction model. • NH3-N risk showed greater spatial variability then temporal variability. • Three key factors influenced NH3-N risk and their contributions were quantified. • NH3-N load capacities and potential hotspots in Chinese mainland were identified. • NH3-N risk will increase by 6.1 % with climate change under the SSP 2-4.5 scenario. [ABSTRACT FROM AUTHOR]

Despite the versatility of RNA m6A methylation in regulating various biological processes, its involvement in the physiological response to ammonia nitrogen toxicity in decapod crustaceans like shrimp remains enigmatic. Here, we provided the first characterization of dynamic RNA m6A methylation landscapes induced by toxic ammonia exposure in the Pacific whiteleg shrimp Litopenaeus vannamei. The global m6A methylation level showed significant decrease following ammonia exposure, and most of the m6A methyltransferases and m6A binding proteins were significantly repressed. Distinct from many well-studied model organisms, m6A methylated peaks in the transcriptome of L. vannamei were enriched not only near the termination codon and in the 3′ untranslated region (UTR), but also around the start codon and in the 5′ UTR. Upon ammonia exposure, 11,430 m6A peaks corresponding to 6113 genes were hypo-methylated, and 5660 m6A peaks from 3912 genes were hyper-methylated. The differentially methylated genes showing significant changes in expression were over-represented by genes associated with metabolism, cellular immune defense and apoptotic signaling pathways. Notably, the m6A-modified ammonia-responsive genes encompassed a subset of genes related to glutamine synthesis, purine conversion and urea production, implying that m6A methylation may modulate shrimp ammonia stress responses partly through these ammonia metabolic processes. [Display omitted] • The first characterization of dynamic m6A methylation landscapes in marine shrimp. • Ammonia exposure induced dramatic m6A methylation changes across the transcriptome. • m6A methylation peaks in the transcripts were highly enriched near the start codon. • Ammonia toxicity led to differential methylation of 17090 m6A peaks in diverse genes. • m6A modification modulate shrimp response to ammonia via ammonia metabolic processes. [ABSTRACT FROM AUTHOR]

This study investigated the performance of immobilized Phanerochaete chrysosporium loaded with nitrogen-doped TiO 2 nanoparticles in the treatment of raw landfill leachate with a very low biodegradability ratio (BOD 5 /COD) of 0.09. The effects of various operating parameters, such as initial chemical oxygen demand (COD) concentration, pH, temperature, and biosorbent dosage, were evaluated with respect to the removal efficiency of total organic carbon (TOC) and ammonia nitrogen (NH 3 –N). For the immobilized biosorbents, an optimum pH of 6.0 for TOC and 7.0 for NH 3 –N were found suitable for TOC and NH 3 –N removal at temperature of 37 °C, respectively. The most superior removal efficiencies of TOC and NH 3 –N of landfill leachate were over 75% and 74% in 72 h at an initial COD concentration of 200 mg L −1 , respectively. In addition, heavy metals were partly removed by the immobilized biosorbents during the process of landfill leachate treatment. The species and mass percentage of organic compounds in landfill leachate after the treatment were found to have considerably declined according to the gas chromatography coupled with mass spectrometry (GC–MS) system. These results indicate that the immobilized P. chrysosporium loaded with nitrogen-doped TiO 2 nanoparticles could be a convenient and efficient method for the treatment of landfill leachate. [ABSTRACT FROM AUTHOR]

Abstract: The few reuse and large stockpile of zeolite tailings led to a series of social and environmental problems. This study investigated the possibility of using the zeolite tailings as one of principal raw materials to prepare sorption functional media (SFM) by a high temperature sintering process. The SFM was used to serve as a biomedium in a biological aerated filter (BAF) reactor for domestic wastewater treatment, and its purification performance was examined. The physical, chemical and sorption properties of SFM were also determined. The microstructure of the SFM was analyzed by scanning electron microscopy (SEM). Results revealed that: (1) zeolite tailings could be used to produce the SFM under the optimal sintering parameters; (2) the sorption and desorption isotherm of ammonia nitrogen on SFM could be well described by the Langmuir formula; (3) in terms of removing organic matter, ammonia nitrogen, turbidity and colourity, the performance of the biofilter with SFM was superior to that with haydite; and (4) SFM BAF has a stronger adaptability to low temperature (6–11°C) for NH3-N removal compared to haydite BAF. Therefore, the SFM produced from the zeolite tailings was suitable to serve as the biomedium in the domestic wastewater treatment. [Copyright &y& Elsevier]

Abstract: The performance of a microbial-earthworm ecofilter for the treatment of synthetic domestic wastewater is evaluated, and the mechanisms of organic matter and nitrogen transformation investigated. Vermifiltration efficiently reduced chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) from the influent. A combination of soil with sawdust possessed higher porosity and specific surface area than other media, and this microporous structure together with wormcast surface greatly facilitated COD reduction at depths from 5 to 35cm. Nitrogen variations in wastewater were influenced by soil properties, earthworm activities, and wormcast characteristics. Their interaction with added nitrogen determined soil nitrogen distribution. In addition, denaturing gradient gel electrophoresis (DGGE) profiles revealed a highly diverse community of ammonia-oxidizing bacteria (AOB) and Nitrospira in soil layers. There was a positive correlation between the Shannon biodiversity index for AOB and decreasing NH3-N concentration, indicating that dominant soil microbes played a major role in removing NH3-N and nitrogen conversion. In contrast to previous reports, identification of retrieved sequences of AOB species showed that most belonged to an uncertain AOB genus. This biofiltration system is a low cost, efficient alternative for decontaminating local domestic wastewater. [Copyright &y& Elsevier]

Abstract: The presence of ammonia nitrogen (NH3–N) in the effluent strongly affected the formation of disinfection by-products (DBPs) during its chlorination. The effect of chlorine (as mg/L Cl2) to NH3–N (as mg/L N) mass ratios (Cl2/N) and the chemical fractions of dissolved organic matter (DOM) in the effluent on the DBPs formation was investigated. Results indicated that the formation of DBPs increased with increasing Cl2/N. The concentration and speciation of DBPs varied among different DOM fractions at different zones of chlorination breakpoint curves. The formation rate of total haloacetic acids (THAA) and total trihalomethanes (TTHM) was promoted after the chlorination breakpoint, whereas the reaction of monochloramine with HOCl to dichloramine may cause a decrease in the DBPs formation potential thereafter. Organic acids were found to be the dominant precursors of DBPs with or without the presence of NH3–N, which indicated that the Clyph name="dbnd" />O and C–O structures contributed to the formation of DBPs significantly. In addition, the incorporation of bromine in THMs of the HiA fraction increased with the increasing of Cl2/N mass ratios before the chlorination breakpoint, but decreased sharply after the breakpoint. ΔA 280 (absorbance at 280nm), defined as A 280,initial − A 280,final, was proved to be linearly related to the TTHM and THAA of wastewater without containing Br− during chlorination or chloramination. [Copyright &y& Elsevier]

Abstract: A large removal of ammonia nitrogen in wastewater has been achieved by microwave (MW) radiation in our previous bench-scale study. This study developed a continuous pilot-scale MW system to remove ammonia nitrogen in real wastewater. A typical high concentration of ammonia nitrogen contaminated wastewater, the coke-plant wastewater from a Coke company, was treated. The output power of the microwave reactor was 4.8kW and the handling capacity of the reactor was about 5m3 per day. The ammonia removal efficiencies under four operating conditions, including ambient temperature, wastewater flow rate, aeration conditions and initial concentration were evaluated in the pilot-scale experiments. The ammonia removal could reach about 80% for the real coke-plant wastewater with ammonia nitrogen concentrations of 2400–11000mg/L. The running cost of the MW technique was a little lower than the conventional steam-stripping method. The continuous microwave system showed the potential as an effective method for ammonia nitrogen removal in coke-plant water treatment. It is proposed that this process is suitable for the treatment of toxic wastewater containing high concentrations of ammonia nitrogen. [Copyright &y& Elsevier]

Abstract: This paper investigated the mechanism and pseudo-kinetics for removal of ammonia by electrochemical oxidation with RuO2/Ti anode using batch tests. The results show that the ammonia oxidation rates resulted from direct oxidation at electrode–liquid interfaces of the anode by stepwise dehydrogenation, and from indirect oxidation by hydroxyl radicals were so slow that their contribution to ammonia removal was negligible under the condition with Cl−. The oxidation rates of ammonia ranged from 1.0 to 12.3mgNL−1 h−1 and efficiency reached nearly 100%, primarily due to the indirect oxidation of HOCl, and followed pseudo zero-order kinetics in electrochemical oxidation with Cl−. About 88% ammonia was removed from the solution. The removed one was subsequently found in the form of N2 in the produced gas. The rate at which Cl− lost electrons at the anode was a major factor in the overall ammonia oxidation. Current density and Cl− concentration affected the constant of the pseudo zero-order kinetics, expressed by k =0.0024[Cl−]× j. The ammonia was reduced to less than 0.5mgNL−1 after 2h of electrochemical oxidation for the effluent from aerobic or anaerobic reactors which treated municipal wastewater. This result was in line with the strict discharge requirements. [Copyright &y& Elsevier]

This study was conducted to improve struvite precipitation for NH4-N removal purpose in landfill leachate. For this purpose, we evaluated the effect of the feeding sequence of precipitating reagents (magnesium, orthophosphate, and buffering reagent) on NH4-N removal by forming struvite deposits. Struvite precipitation effectively proceeded by an addition of excess magnesium and phosphate sources followed by an addition of the buffering reagent, in which condition the local formation of inappropriate deposits or the contamination of the desired struvite was minimized. We also tested the effect of struvite addition as the seeding materials on NH4-N removal. Seed addition would increase the potential for the struvite crystal growth, which enhanced NH4-N removal performance in landfill leachate treatment. [Copyright &y& Elsevier]

Electrolytic manganese residue (EMR) has become a barrier to the sustainable development of the electrolytic metallic manganese (EMM) industry. EMR has a great potential to harm local ecosystems and human health, due to it contains high concentrations of soluble pollutant, especially NH 4 + and Mn2+, and also the possible dam break risk because of its huge storage. There seems to be not a mature and stable industrial solution for EMR, though a lot of researches have been done in this area. Hence, by fully considering the EMM ecosystem, we analyzed the characteristics and eco-environmental impact of EMR, highlighted state-of-the-art technologies for EMR reduction, pretreatment, and reuse; indicated the factors that block EMR treatment and disposal; and proposed plausible and feasible suggestions to solve this problem. We hope that the results of this review could help solve the problem of EMR and thus promote the sustainable development of EMM industry. [Display omitted] • The EMM industry and the characteristics of EMR are analyzed. • The state-of-the-art technologies for EMR treatment and disposal are discussed. • The factors that block EMR treatment and disposal are pointed out. • Plausible and feasible suggestions on EMR treatment and disposal are proposed. [ABSTRACT FROM AUTHOR]

Ammonia nitrogen and phenol are typical inorganic and organic pollutants in the coal chemical wastewater, respectively. In this study, the adsorption characteristics of ammonia nitrogen and phenol on lignite were investigated through experimental and molecular dynamics simulations. The results show that the adsorption of ammonia nitrogen was carried out via ion exchange, which was significantly faster than the adsorption of phenol driven by the π–π interaction. In the binary adsorption, the surface electronegativity of lignite decreased with the adsorption of ammonia nitrogen thereby promoting the adsorption of phenol. However, the extent of ammonia nitrogen adsorption was slightly reduced in the presence of phenol. Molecular dynamics simulation results indicated that the adsorption of phenol molecules on the lignite surface was closer than that of ammonium ion. The addition of ammonium ions could enhance the adsorption of phenol molecules on the lignite surface. The simulation results were well consistent with the experimental findings. This study indicates lignite has a promising potential in coal chemical wastewater adsorption pretreatment. [Display omitted] • Lignite adsorption was based on mesopores and oxygen functional groups. • The adsorption rate of NH 4 +-N on lignite was faster than that of phenol. • The adsorption quantity of phenol on lignite was increased by NH 4 +-N. • MD Simulation provided atomic-scale details of adsorption. [ABSTRACT FROM AUTHOR]

• The effects of substrate-driven toxicants on AD were reviewed. • The mechanisms of toxic substances affecting MA were comprehensively analyzed. • Acetoclastic pathway has less resistance than other methane-producing pathways. • Toxicity includes both direct (cell) and indirect (metabolic environment) impacts. Anaerobic digestion (AD) is used to treat waste and produce bioenergy. However, toxicants, which originate from the substrate, can inhibit or damage the digestion process. Methanogenic archaea (MA), which are the executor in the methanogenesis stage, are more sensitive than bacteria to these toxicants. This review discusses the effects of substrate-driven toxicants, namely, antibiotics, H 2 S and sulfate, heavy metals (HMs), long-chain fatty acids (LCFAs), and ammonia nitrogen, on the activity of MAs, methanogenic pathways, and the inter-genus succession of MAs. The adverse effects of these five toxicants on MA include effects on pH, damages to cell membranes, the prevention of protein synthesis, changes in hydrogen partial pressure, a reduction in the bioavailability of trace elements, and hindrance of mass transfer. These effects cause a reduction in MA activity and the succession of MAs and methanogenic pathways, which affect AD performance. Under the stress of these toxicants, succession occurs among HA (hydrogenotrophic methanogen), AA (acetoclastic methanogen), and MM (methylotrophic methanogen), especially HA gradually replaces AA as the dominant MA. Simultaneously, the dominant methanogenic pathway also changes from the aceticlastic pathway to other methanogenic pathways. A comprehensive understanding of the impact of toxicants on MA permits more specific targeting when developing strategies to mitigate or eliminate the effects of these toxicants. [ABSTRACT FROM AUTHOR]

• Co-addition of H 2 O 2 and PMS in the VUV photoreactor resulted in synergic ammonia removal. • Ammonia removal rate in the VUV/H 2 O 2 /PMS was 3.5 times higher of that in the VUV process. • >99 % nitrogen gas selectivity was obtained in the VUV/H 2 O 2 /PMS process. • Ammonia, TOC & bacteria were efficiently removed in continuous flow VUV/H 2 O 2 /PMS process. In this work, the VUV, VUV/H 2 O 2 , VUV/PMS, and VUV/H 2 O 2 /PMS processes were compared with the corresponding UVC-based AOPs under identical experimental conditions for the ammonia removal. Among the examined AOPs, the VUV/H 2 O 2 /PMS demonstrated the highest performance in converting N H 4 + to N 2. A 82.7 % removal of 100 mg/L N H 4 + , with N 2 selectivity over 99 % was obtained in the VUV/H 2 O 2 /PMS process within 60 min, operated under near neutral pH. Under these operation conditions, [ N O 3 - ] was around 0.5 mg-N/L with [ N O 2 - ] remaining below detection. The VUV-mediated generation of S O 4 • - a n d H O • with N H 4 + had a relative contribution of 37.9 and 62.1 %, respectively. The VUV/H 2 O 2 /PMS process operated under a flow-through mode achieved efficient removal of 100 mg/L N H 4 + (80.5 %) in a hydraulic retention time (HRT) of 40 min. The continuous-flow VUV/H 2 O 2 /PMS process efficiently treated a real ammonia-laden groundwater and the concentration of N H 4 + decreased from 30 mg/L to around 1 mg/L within 60 min HRT. In summary, the VUV/H 2 O 2 /PMS process was effective from the technical and energetical point of view, hence is a viable and promising technique for treating effluent containing high concentrations of ammonia. [ABSTRACT FROM AUTHOR]

• The plasma/zeolites combined system was used to treat ammonia nitrogen. • The migration and conversion of ammonia nitrogen and its products in solution and on zeolites were studied. • The addition of zeolites caused the decomposition of O 3 and H 2 O 2 in the plasma system. • The plasma/zeolites system enhanced the oxidation of pollutants. In this work, non-thermal plasma combined with zeolites was used to remove inorganic pollutant ammonia nitrogen from wastewater. Ammonia nitrogen elimination performances at various operating parameters were investigated. Roles of active species in the removal of ammonia nitrogen were also discussed. The experimental results showed that 69.97% ammonia nitrogen can be removed from the plasma/zeolites synergistic system after 30 min treatment. The removal efficiency was 16.23% and 61.55% higher than that in sole zeolites adsorption system and that in sole discharge plasma system, respectively. Higher applied voltage, lower initial ammonia nitrogen concentration and weak acidic conditions were favorable for ammonia nitrogen removal. After the addition of zeolites, part of O 3 and H 2 O 2 generated in the plasma/zeolites system were decomposed into other oxygen species (•OH and 1O 2), which improved the oxidation degree of ammonia nitrogen. In addition, the reaction mechanism of ammonia nitrogen in water by plasma/zeolites process was discussed. After repeated use three times, the effect of the zeolites in the plasma/zeolites system remained stable. Characterization of the zeolites after reaction was analyzed through BET, SEM, XRD and FT-IR. The experiments have confirmed the applicability of the plasma/zeolites system for the further treatment of low-concentration ammonia nitrogen wastewater. [ABSTRACT FROM AUTHOR]

• Novel method of impregnation with a sodium nitrate solution followed by calcination was proposed for NZ modification. • Improved mesoporous characteristics coupled with ion-exchange significantly enhanced the ammonium removal capability of NZ. • Ammonia adsorption kinetics, isotherms and thermodynamics of the modified NZ were systematically elucidated. • Effect of co-existing ions, pH and dosage the adsorption performance of the modified NZ was clarified. Ammonium is one of the key factors responsible for the eutrophication of water bodies. The purpose of this study was to remove ammonium from water using a natural zeolite (NZ) modified with sodium nitrate (NaNO 3) by impregnation and calcination. The ability of the NZ to remove ammonium from water was determined by single calcination; however, its efficiency was significantly enhanced by impregnation with a NaNO 3 solution. Zeolite modified with 3.00 M NaNO 3 and calcination at 673 K yielded the best ammonium removal efficiency, which was 39.88 % higher than the NZ alone. The zeolites that were regenerated over six times maintained a removal rate of 79.35–84.79 % by mixing 25.0 mg of the NZ into 50 mL of a 5.0 mg/L ammonium solution. The improved performance of the modified zeolite (q m , 16.96 mg/g) was mainly attributed to its relatively elevated mesopore volumes and higher ion-exchange capacity that results from nitrate decomposition, oxygen release, and sodium-ion exchange. The adsorption kinetics and isotherms are best described by the pseudo-first-order (PFO) and Freundlich model, respectively, and the process was endothermic. The effects of other factors, including coexisting ions, pH, and dosage, on ammonium adsorption were also determined. [ABSTRACT FROM AUTHOR]