Nitrogen Pollution Research Articles

Review of the Seasonal Wastewater Challenges in Baltic Coastal Tourist Areas: Insights from the NURSECOAST-II Project

The NURSECOAST-II project addresses the challenge of managing wastewater in near-coastal tourist destinations around the Baltic Sea, particularly from small treatment plants (<2000 PE) that experience fluctuating flows due to seasonal tourism. These fluctuations make it difficult to meet environmental standards, potentially harming both the environment and tourism. The project has created a GIS-based inventory of small wastewater treatment plants within 100 km of the coast. This inventory includes crucial operational data like flow rates, pollutant levels, and treatment technologies. Initial findings reveal significant discrepancies in data management, regulations, and treatment standards across the Baltic Sea region countries, as EU legislation does not uniformly cover plants under 2000 PE. Key findings highlight that small treatment plants are often undocumented, their environmental impact underestimated, and regulations vary widely. Small plants can significantly contribute to nutrient pollution, affecting the Baltic Sea, particularly in local areas. The data gathered will support local authorities in identifying gaps and improving management strategies. This study stresses the need for harmonized data collection and reporting methods across countries and suggests establishing a unified database accessible to both specialists and the public. The status of the collected data depending on the type of data and country was as follows: 38.11% from Denmark, 46.14% from Estonia, 26.36% from Finland, 15.56% from Germany, 23.47% from Latvia, 34.77% from Lithuania, 14.51% from Poland, and 45.40% from Sweden. Ultimately, this project aims to enhance wastewater management, protect the environment, and improve tourist satisfaction in coastal regions.

Temporal and Spatial Dynamics of Carbon, Nitrogen, and Phosphorus in a Subtropical Urban River (Tamanduateí River, São Paulo, Brazil)

Water quality in urban streams often reflects the broader environmental challenges posed by dense population centers, where pollution from untreated sewage and runoff can significantly degrade ecosystems. This study examines the spatial and temporal variations of carbon, nitrogen, and phosphorus concentrations in the Tamanduateí River, which runs through the Metropolitan Region of São Paulo, Brazil. Data were sourced from the annual reports of the Environmental Company of the State of São Paulo (CETESB) covering the period from 2011 to 2022. Between 2011 and 2017, carbon and phosphorus concentrations declined, likely due to sanitation improvements. However, since 2017, these concentrations have been rising again, indicating renewed pollution inputs, primarily from untreated sewage. Nitrogen levels remained consistently high, with elevated concentrations observed upstream, linked especially to domestic effluent discharges. The recent increase in phosphorus levels is also of concern. The absence of spatial variation in phosphorus suggests diffuse pollution from urban areas, while nitrogen decreases downstream, possibly due to biological assimilation. The study underscores the pressing need for enhanced sewage management. Drawing from the successful revitalization of the Cheonggyecheon stream in Seoul, implementing nature-based solutions and regular maintenance could effectively reduce nutrient pollution and improve water quality, facilitating the restoration of the Tamanduateí River.

Evaluation of Agricultural Non-point Source Pollution Infiltration on Clogging and Nitrogen Leaching Effects in BRCs with Different Plants in Dryland Areas.

As high-standard farmland rapidly expands, agricultural non-point source pollution has emerged as a main environmental issue in China. To tackle nitrogen pollution, green infrastructure (GI), especially bioretention cells (BRCs), has been extensively adopted. However, the long-term effectiveness of these systems may be hindered by clogging and nitrogen leaching. In this study, we designed three BRCs simulation devices to investigate the effects of different plants on the removal of TSS TN and NO3-N from runoff through simulated pollutant infiltration experiments. To address this issue, laboratory research has explored the contributions of woody plants like Buxus and herbaceous plants such as Ophiopogon in BRCs, concentrating on their impact on system clogging and nitrogen leaching. The results indicated that, although the total suspended solids (TSS) removal rates in the Buxus and Ophiopogon treatment groups were slightly lower than in the control group, permeability experienced a notable enhancement, with the Buxus group showing a 24.47% increase in permeability. The removal rates of TN and NO3-N in the Buxus group were significantly reduced, decreasing by 31.82% and 41.25%, respectively, in comparison to the control group. After five months, Ophiopogon demonstrated considerably better root growth, with its root length, volume, and surface area all significantly exceeding those of the Buxus group. The choice of plants significantly influenced nitrogen cycling and system clogging, with the reduced removal rates in the Buxus group potentially linked to its weaker root system, lower abundance of actinomycetes, and reduced soil enzyme activity.

Removal of Phosphate from Water by Iron/Calcium Oxide-Modified Biochar: Removal Mechanisms and Adsorption Modeling

Phosphorus (P) pollution is a leading cause of water eutrophication, and metal-modified biochar is an effective adsorbent with the ability to alter the migration capacity of phosphorus. This study uses bamboo as the raw material to prepare metal-modified biochar (ZFCO-BC) loaded with Fe and Ca under N2 conditions at 900 °C, and investigates its adsorption characteristics for phosphate. Batch experimental results show the adsorption capacity of the ZFCO-BC gradually increases (from 4.0 to 69.1 mg/g) as the initial phosphate concentration increases (from 2 to 900 mg/L), mainly through multilayer adsorption. Additionally, as the pH increases from 1 to 7, the adsorption capacity of the ZFCO-BC climbs to reach its maximum value of 48.4 mg/g with an initial phosphate concentration of 150 mg/L. At this pH, phosphate primarily exists as H2PO4− and HPO42−, which both readily react with Fe3+ and Ca2+ in the biochar. Furthermore, the addition of CO32−, HCO3−, NO3−, SO42−, F−, and Cl− each affect the removal rate of phosphate by less than 10%, indicating the ZFCO-BC has a highly efficient and selective phosphate adsorption capacity. A multi-column adsorption experiment designed to achieve long-term and efficient phosphorus removal treated 275.5 pore volumes (PVs) of water over 366 h. The cyclic adsorption–desorption experiment results show that 0.5 M NaOH can effectively leach phosphate from the ZFCO-BC. Observations at the molecular level from P K-edge XANES spectra confirm the removal of low-concentration phosphate is primarily dominated by electrostatic attraction, while the main removal mechanism for high-concentration phosphate is chemical precipitation. This study demonstrates that ZFCO-BC has broad application prospects for phosphate removal from wastewater and as a potential slow-release fertilizer in agriculture.

Mechanically Induced Green Targeted Conversion of Ammonia Nitrogen to N2: Based on Cavitation Effects and ROS Oxidation.

Addressing the mounting challenge of ammonia nitrogen pollution in aquatic ecosystems necessitates the selective oxidation of ammonia nitrogen to nitrogen gas, a pivotal aspect of eco-friendly nitrogen removal processes. Ultrasound cavitation, renowned for its capacity to generate reactive oxygen species (ROS), has garnered considerable attention in environmental remediation. This study reveals a highly synergistic mechanism in ultrasound coupled stirring (US-ST), establishing optimal coupling conditions through sound field monitoring and quantification of ROS. In comparison to ultrasound treatment alone (US), the sound pressure amplitude significantly increased from ±18 to ±30 kPa in US-ST, markedly reducing the cavitation nucleation threshold and augmenting the steady-state concentration of hydroxyl radicals (HO•) by 13-fold. Further, with appropriate charge transfer conditions enabled by the acoustoelectric characteristics of the passive film on stirring paddles, the concentrations of superoxide (•O2-) and singlet oxygen (1O2) elevated to 9.54 × 10-10 M and 8.43 × 10-13 M, respectively. Under the regulation of 500 rpm stirring vortex, a maximum sonochemical efficiency of 6.5 × 105 mg J-1 was achieved. In the context of domestic wastewater, ammonia nitrogen degradation was achieved through the oxidation and thermal dissociation effects of US-ST. The concentration decreased from 27.5 to 3.4 mg/L after 2 h, with an impressive N2 selectivity of 96.8%. This study elucidates the targeted conversion mechanism of ammonia nitrogen in US-ST, introducing an emerging water treatment technology propelled by mechanical energy.

Pollutant emission during pyrolysis of waste wind turbine blades: Nitrogen-containing components and polycyclic aromatic hydrocarbons

Serious attention was lacked for various pollutants formed in both gas and tar phase during pyrolysis recycling of waste wind turbine blades (WWTB), especially for components of carcinogenic bisphenol A (BPA) and potentially toxic polycyclic aromatic hydrocarbons (PAHs) in tar. Pyrolysis temperature within 400–600 °C would significantly impact pollutant formations. Additionally, CO2 had a potential to mitigate pollutants emission as an economic alternative for N2. This article investigated the influence of these factors on nitrogenous and PAHs components during WWTB pyrolysis through fixed bed and thermogravimetric experiments. The results showed that NO2 was dominated in nitrogen containing pollutants and was related to the evolution of pyrrole nitrogen oxides. It was found 550 °C as a turning temperature, at which the polycondensation reaction appeared significantly. This resulted in a markedly increase for toxic N-PAHs in tar. At this temperature, CO2 could be used to mitigate nitrogen pollutants. 25% CO2 reduced NOX emission about 26% and selectively promoted NH3 releasing to over 4.3 times and depressed HCN generating to 0.6 times. Moreover, the primary depolymerization product of organic pact in WWTB was BPA. Increasing residence time, temperature and CO2 concentration were beneficial for converting hazardous BPA to high valued P-Isopropenylphenol (IPP). The value of IPP:BPA could increase to over 2 in this experiment. It was aimed to provide not only an evaluation for the yield and migration of pollutants, but also an cleaner recycling solution through graded pyrolysis WWTB to mitigate pollution and maximize the value of by-products.

Identification of groundwater nitrate sources and its human health risks in a typical agriculture-dominated watershed, North China.

Identifying nitrate sources and migratory pathways is crucial for controlling groundwater nitrate pollution in agricultural watersheds. This study collected 35 shallow groundwater samples in the Nansi Lake Basin (NLB) to identify groundwater nitrate sources and potential health risks. Results showed that NO3- concentration in 62.9% of groundwater samples exceeded the drinking water standard (50 mg/L). Hierarchical cluster analysis (HCA) was used to classify the sampling points into three groups based on hydrochemical and isotopic data. Groups A and C were situated in the eastern recharge and discharge regions of Nansi Lake, while Group B was located in the Yellow River floodplain west of the lake. Hydrochemical data and nitrate stable isotopes (δ15N-NO3- and δ18O-NO3-) indicated that elevated NO3- primarily originated from soil organic nitrogen (SON) in Group A, while manure and sewage (M&S) were the primary sources in Groups B and C samples. Microbial nitrification was identified as the primary nitrogen transformation process across all groups. The source apportionment results indicated that SON contributed approximately 40.1% in Group A, while M&S contributed about 53.9% and 81.2% in Groups B and C, respectively. The Human Health Risk Assessment (HHRA) model indicated significant non-carcinogenic risks for residents east of Nansi Lake, primarily through the oral pathway, with NO3- concentration identified as the most influential factor by sensitivity analysis. These findings provide new perspectives on identifying and handling groundwater nitrogen pollution in agriculture-dominated NLB and similar basins that require enhanced nitrogen contamination management.

Sewage-and fertilizer-derived nutrients alter the intensity, diversity, and toxicity of harmful cyanobacterial blooms in eutrophic lakes

Cyanobacterial harmful algal blooms (CHABs) are promoted by excessive nutrient loading and, while fertilizers and sewage are the most prevalent external nutrient sources in most watersheds, the differential effects of these nutrient sources on CHABs are unknown. Here, we tracked CHABs and performed experiments in five distinct lakes across the Northern US including Lake Erie. Fertilizers with ammonium and orthophosphate, membrane (0.2 μm)-filtered sewage (dominated by reduced forms of nitrogen) sand-and membrane-filtered sewage (dominated by nitrate), and an inorganic nutrient solution of ammonium and orthophosphate were used as experimental nutrient sources for CHABs at N-equivalent, environmentally realistic concentrations. Phytoplankton communities were evaluated fluorometrically, microscopically, and via high throughput sequencing of the 16S rRNA gene, and levels of microcystin and the δ15N content of particulate organic nitrogen (δPO15N) were quantified. Fertilizer and both sources of wastewater increased the abundance of cyanobacteria in all experiments across all five lakes (p < 0.05 for all) whereas effects on eukaryotic phytoplankton were limited. Sand-filtered sewage contained less P, organic matter, and ammonium but more nitrate and had a 25% less potent stimulatory effect on cyanobacteria than membrane-filtered sewage, suggesting nitrification may play a role in reducing CHABs. Fertilizer increased microcystin levels and decreased the δPO15N whereas wastewater increased δPO15N (p < 0.05 for all). Microcystis was the genus most consistently promoted by nutrient sources (p < 0.05 in all experiments), followed by Cyanobium (p < 0.05 in 50% of experiments), with increases in Microcystis biomass consistently elicited by membrane-filtered wastewater. Collectively, results demonstrate that differing types of sewage discharge and fertilizers can promote CHAB intensity and toxicity, while concurrently altering CHAB diversity and δPO15N. While membrane-filtered sewage consistently favored Microcystis, the discharge of sewage through sands muted bloom intensity suggesting sand-beds may represent a tool to remove key nutrients and partially mitigate CHABs.

Economic-ecological assessment of multi-crop small-scale model farms in the Republic of Armenia (piloting results from Gegharqunik region)

Background: Biogenic elements such as nitrogen (N), phosphorus (P), and potassium (K) are major pollutants of Lake Sevan's water, causing eutrophication and deterioration of water quality. Untreated wastewater, sewage, agriculture, fish farming, and other activities are significant sources of these pollutants. Vegetable cultivation, heavily reliant on mineral fertilizers and chemicals, and livestock breeding contribute substantially to nitrogen pollution in the lake. However, improved vegetable growing practices, including small-scale agriculture using organic fertilizers, natural soil improvers, and eco-friendly bio-liquids as growth stimulants, can enhance the socio-economic conditions for farmers in the Lake Sevan basin. These practices promote environmentally friendly, water-saving land-use methods, reducing nitrogen leaching into the lake. Objective: This study aims to demonstrate the socio-economic and environmental benefits of applying innovative agro-technology to small-scale farming in the Lake Sevan watershed (Gegharkunik region). Specifically, the study objectives are to determine the quality characteristics of crops grown in small-scale farms and compare these quality indicators between yields obtained through the proposed technology and traditional cultivation methods. Methods: Field trials of multi-crop systems were conducted on 0.25 ha land plots in four variations across four different locations in the Lake Sevan watershed. The trials were evaluated for various parameters. Nitrate content, dry matter, starch, vitamin C, and sugar levels were determined in potatoes, cabbage, broccoli, beets, and green beans, while fat content was measured in green beans and green peas. Results: Economic efficiency calculations revealed that utilizing the proposed innovative agro-technology in a multi-crop small-scale farm (0.25 ha) yielded a 20-25% increase compared to traditional cultivation with synthetic fertilizers, accompanied by notable environmental benefits. Conclusions: The study demonstrates that small-scale agricultural practices employing the proposed agro-technology have significant socioeconomic and environmental impacts on local farmers. Keywords: Cultivation of non-traditional crops, organic farming, small-scale farming, activities, economic and ecological evaluation, and food quality characteristics.

Food and land system transformations under different societal perspectives on sustainable development

Abstract The future of food and land systems is crucial for achieving multiple UN Sustainable Development Goals, given their essential role in providing adequate nutrition and their significant impact on Earth system processes. Despite widespread consensus on the need for transformation, discussed strategies vary widely, from technology-driven to sufficiency-focused approaches, emphasizing different agents of change and policy mixes. This study assesses the implications of a new generation of target-seeking scenarios incorporating such diverse sustainability perspectives. We apply two integrated assessment models to explore food and land futures under three whole-economy Sustainable Development Pathways (SDPs): Economy-driven Innovation, Resilient Communities, and Managing the Global Commons. Our assessment shows that all SDPs align sufficient food supply with progress towards planetary integrity, halting biodiversity loss, mitigating adverse impacts from irrigation, and significantly reducing nitrogen pollution. While all pathways comply with the Paris climate target, they diverge in the timing of climate mitigation efforts and focus on different greenhouse gases and emission sources. The Economy-driven Innovation pathway rapidly achieves net-negative CO2 emissions from the land system, whereas Resilient Communities and Managing the Global Commons significantly decrease agricultural non-CO2 emissions. Moreover, sustainability interventions attenuate trade-offs associated with narrowly focused mitigation pathways and reduce reliance on carbon dioxide removal strategies like re/afforestation and bioenergy with carbon capture and storage.

The condition status index for doline lakes in urban areas

Karst represents approximately 15% of the planet’s surface, hundreds of millions of people live on and rely on these aquifers for water supply and agricultural irrigation. In karstic landscapes, groundwater is exposed in sinkholes, inundated caves, and artesian wells, which are two-way communication spots. When the phreatic level is exposed, the groundwater can change substantially as a result of anthropogenic impacts, modifying the water quality and the environmental integrity by incoming excess nutrients, contaminants, pathogens, and other hazardous substances such as metals and microplastics. In this paper, we develop and test a multimetric index to evaluate the condition status of dolines located within urban areas, including seven indicators: trophic index, fecal bacteria, fecal viruses, microplastics, heavy metals, zooplankton biodiversity, and fish biodiversity. Lastly, we made a proof of concept for the index in the dolines on the island of Cozumel (Mexico), resulting in evaluations from fair to good. The index is powerful due to its sensitivity to pathogens and exotic invasive species. This additive weighted index allows to assess the condition status of dolines in urban areas anywhere in the world; if required, modifications are possible.

Spatio-Temporal Analysis of Net Anthropogenic Phosphorus Inputs (NAPIs) and Their Impacts in Ningxia Hui Autonomous Region Using Monte Carlo Simulations and Sensitivity Analysis

This study employed the Net Anthropogenic Phosphorus Inputs (NAPI) model to assess the impact of human activities on phosphorus input in a watershed, analyzing county-level statistical data and NAPI model parameters from 1991 to 2020. The Monte Carlo method was used for a quantitative analysis of the model parameters’ effects on each NAPI component and the overall simulation results. The sensitivity index method identified each component’s sensitive parameters. The study found that the lowest NAPI value was 454 kg/(km2·a) in 1991 and the highest was 1336 kg/(km2·a) in 2003. NAPI in Ningxia showed an overall upward trend from 1991 to 1999, a slight decrease from 1999 to 2003, and a slight increase from 2003 to 2020, with fertilizer being the main contributing factor, accounting for 77.4% of the total input. On a spatial scale, NAPI in Ningxia was significantly correlated with land use patterns, showing higher values in the northern and southern regions compared to the central part. The NAPI values derived from Monte Carlo simulations with appropriate parameters ranged from −24.83% to 31.49%. The study highlighted the net food and feed imports component as having the highest uncertainty, impacting simulation results within a range of −23.89% to 53.98%. It was observed that the larger a component’s proportion in the NAPI model, the more sensitive its parameters, with the phosphorus fertilizer (Pfer) component’s parameters being notably more sensitive than those of the food/feed phosphorus input and the non-food phosphorus input (Pnf) components. These findings can inform phosphorus pollution control policies in Northwest China, while the selection of sensitive parameters provides a useful reference for future NAPI research in other regions.

Effect of Nano-fertilizers in Wheat Crop Nutrition: A Review

The use of nano - fertilizers in wheat cultivation represents a promising approach to overcoming some of the inefficiencies and environmental challenges associated with conventional fertilizer practices. Traditional fertilizers often suffer from low nutrient use efficiency, leading to excessive application, nutrient runoff, and environmental harm. Nano fertilizers, due to their nano-scale size and enhanced reactivity, improve nutrient uptake by plants, leading to better growth, higher yields, and reduced nutrient wastage. Studies show that Nano formulations of both macronutrients (such as nitrogen, phosphorus, and potassium) and micronutrients (like zinc and iron) can significantly enhance wheat productivity. Nano fertilizers not only increase crop yield but also reduce the overall cost of fertilizer application by minimizing nutrient loss and improving absorption by the plants.

Vulnerability of kelp, Ecklonia radiata, to persistent nitrogen pollution and coastal darkening

Coastal darkening is expected to have pervasive impacts on benthic primary producers. However, the effects of nitrogen enrichment, an often-co-occurring stressor, on benthic primary producers and their functions is less clear. This study investigates the interactive effects of coastal darkening and nitrogenous eutrophication, including nitrogen source (NH4+ vs. NO3−), on the function of the kelp Ecklonia radiata. First, an in-situ experiment was used to assess the differential impacts of NH4+ and NO3− pulse enrichment on the photosynthetic performance and pH modulation capacity of E. radiata. Second, a laboratory experiment was used to assess the longer-term impacts of nitrogen enrichment under low-light conditions mimicking coastal darkening on service provisioning, including photosynthetic performance, pH modulation, nutrient uptake and growth. While pulse nitrogen enrichment had no impacts on the photosynthetic performance of E. radiata in-situ, persistent exposure to either NH4+ or NO3− acted as a stressor to sporophytes as indicated by elevated rates of dark respiration and lamina erosion and reduced photosynthetic efficiency and growth rates. Furthermore, low-light conditions elicited reduced photosynthetic capacity at saturating irradiance, which extended to a reduction in the extent of pH modulation, and significantly increased lamina erosion. While the two stressors appeared to act on distinct parameters, ultimately, both darkening and eutrophication directly reduced net primary production, especially when in combination. These results demonstrate the negative interactive effects of coastal darkening and eutrophication on E. radiata function, while suggesting a vulnerability of E. radiata to even moderate levels of persistent nitrogen enrichment. This vulnerability highlights the need to consider environmental conditions during kelp conservation and restoration, and when attempting to valorise kelp ecophysiology for nature-based solutions.

Microbial Ecology of Denitrification Process and Its Application in Wastewater: Treatment, Challenges and Opportunities

Denitrification is a crucial microbial process in the nitrogen cycle, transforming nitrate (NO₃⁻) into nitrogen gas (N₂), thereby mitigating nitrogen pollution in aquatic ecosystems. This microbial activity plays a vital role in wastewater treatment by removing excess nitrogen, which contributes to eutrophication and water contamination. The denitrification process involves various microbial communities, including bacteria such as Pseudomonas, Paracoccus, and Bacillus, which operate under anoxic conditions to achieve nitrogen reduction, an optimizing denitrification in wastewater treatment presents several challenges, such as maintaining ideal environmental conditions (e.g., carbon availability, oxygen levels, pH) and overcoming issues related to incomplete denitrification, which can lead to the production of harmful intermediates like nitrous oxide (N₂O). Despite these hurdles, recent advancements in microbial ecology, such as the use of biofilms, bioreactors, and genetic engineering, offer promising opportunities to enhance denitrification efficiency. This review explores the microbial ecology of the denitrification process, its application in wastewater treatment, and the challenges and opportunities associated with its practical implementation in reducing nitrogen pollution.

Nano-Fe3O4/FeCO3 modified red soil-based biofilter for simultaneous removal of nitrate, phosphate and heavy metals: Optimization, microbial community and possible mechanism

The pollution of nitrogen, phosphorus and heavy metals in surface water is becoming more and more serious, affecting the safety of water quality. In this study, three biofilters were constructed using iron-modified red soil-based filler carriers (RSC, nano-Fe3O4@RSC, and FeCO3@RSC) combined with strain Zoogloea sp. ZP7 to simultaneously remove nitrate (NO3--N), phosphate (PO43--P), copper (Cu2+), and zinc (Zn2+). The long-term operation results showed that the three groups of biofilters could remove 85.0, 90.0, and 89.8% of NO3--N, respectively. Furthermore, the addition of iron compounds enhanced the removal of PO43--P and the resistance to the stress of Cu2+ and Zn2+ in the biofilter. The analysis illustrated that iron modification improved the redox activity and zeta potential of RSC surface. The secondary structure analysis of the protein showed that the microbial secreted proteins were more compact on the surface of the iron-modified RSC, which facilitated the formation of biofilm on the carrier surface. In addition, the iron-modified RSC-based biofilter also showed excellent NO3--N and PO43--P removal efficiency in the treatment of actual surface water. The microbial community analysis results showed that Zoogloea became the dominant species in the biofilter. On the other hand, the presence of iron-reducing bacteria and the expression iron cycle-related genes may contribute to denitrification under low nutrient conditions.

Phosphorus removal performance of Sulfide-Based autotrophic denitrification process

Sulfide-based Autotrophic Denitrification (SAD) Process can simultaneous remove sulfurous and nitrogenous pollutants, showing a promising prospect. Beyond our expectation, it also has an efficient phosphorus (P) removal performance. The operation results demonstrated that when the influent concentration of nitrate, sulfide and phosphate was 80.55 ± 2.98 mg N/L, 380.15 ± 20.83 mg S/L and 47.70 ± 4.35 mg P/L respectively, their removal efficiency was 87.63 ± 3.12 %, 99.61 ± 1.02 % and 85.38 ± 4.07 % at the HRT of 8.8 h. However, the phosphorus removal performance disappeared once the effluent pH dropped below 8.0. The random forest regression model revealed that effluent pH had the most significant impact on phosphorus removal performance. This finding was corroborated by a mathematical model that related the phosphate removal load to effluent pHs. The combination of batch test, Standard Measurements and Testing (SMT) and X-Ray Diffraction (XRD) method revealed that the phosphorus removal performance of SAD process came from the synergies of biological phosphorus removal (29.71 ± 3.21 %) and bio-induced phosphate precipitation (70.29 ± 3.21 %). The analysis of key functional genes coding for nitrogen, sulfur and phosphorus metabolism offered an explanation for their metabolic pathways especially the phosphorus removal pathway. The study would provide some new information for the development of SAD process.

Facile constructing ZrO2 nanoparticles equipped with high conductivity carbon networks as pseudocapacitive anodes for removing phosphorus

Phosphorus pollution can seriously disrupt water quality and endanger ecosystem sustainability. Nonetheless, a few typical methods have been employed to remove phosphorus, but there are still challenges in controlling phosphorus from sewage. Capacitive deionization (CDI) displays the merits of having eco-friendliness and low energy consumption when capturing phosphorus. However, traditional carbon electrodes often suffer from the limitation that phosphorus uptake sites are insufficient. Herein, a novel ZrO2 nanoparticle equipped with a highly conductive carbon network (NZrC) was fabricated by a facile co-pyrolysis process. Na2EDTA can provide additional carbon backbones, N species, and metal chelation sites. Zr-MOF was applied as the ZrO2 precursor with abundant phosphorus trapping sites. The results suggested that Na2EDTA favors improving the ZrO2 dispersion, mesoporous channel formation, and pseudocapacitive behavior. NZrC-21 at 1.2 V displays low energy consumption and the optimal phosphorus uptake capacity of 10.99 mg P/g because of its rich mesoporous structure, abundant pyrrolic-N, graphitic-N, and ZrO2 active sites, and outstanding electrochemical properties. Furthermore, several key parameters were investigated for their effect on phosphorus removal performance. The mechanism revealed that hydrogen bonds, ligand exchange, and electrostatic attraction are the main uptake processes. This work presents a novel perspective for the facile construction and utilization of metal oxide nanoparticles equipped with a highly conductive carbon network for removing phosphorus.

Elucidating the formation pattern and mechanism of biofouling layer regulated by pre-deposition of powdered activated carbon in gravity-driven membrane systems

Powdered activated carbon (PAC) pre-deposition promotes pollutant removal in gravity driven membrane (GDM) but diversely affects flux. This study evaluated the effects of one-time deposition (GDM 1), batch deposition (GDM 2) and no deposition (GDM 3) of PAC on the biofouling layer formation mechanism and the GDM performance. The results showed that PAC particles effectively promoted the removal of dissolved organic carbon, ammonia nitrogen and fluorescent pollutants, while also significantly reducing the concentration of extracellular polymeric substances in the biofouling layer. The stable flux in GDM 1–3 were 6.58, 7.88 and 8.61 LMH respectively. One-time deposition of PAC compromised the structure of the biofouling layer and prevented its reverse relaxation. Pollutant floc particles continuously accumulated in the space between the PAC particles, forming a dense layer with low porosity and roughness. In GDM 2, the limited amount of PAC deposited each time helped to partially maintain the intact structure of the biofouling layer, which alleviated the decline in flux. The reverse relaxation of the intact biofouling layer in GDM 3 resulted in increased porosity, which positively influenced the flux. Additionally, the abundance of Bdelloidea significantly decreased in GDM 1 and GDM 2, and more predators with low agility showed limited modification on the biofouling layer, resulting in a dense biofouling layer. In conclusion, batch deposition of PAC is more recommended as the continuously renewed PAC promote pollutant removal, and compared with one-time deposition of PAC, the reduction in biofouling layer disturbance mitigates the flux decline.

Guidance for establishing and applying tolerable upper intake levels for vitamins and essential minerals.

Vitamins and essential minerals are micronutrients that are required for the normal functioning of the human body. However, they may lead to adverse health effects if consumed in excess. A tolerable upper intake level (UL) is a science-based reference value that supports policy-makers and other relevant actors in managing the risks of excess nutrient intake. EFSA's principles for establishing ULs for vitamins and minerals were originally developed by the Scientific Committee on Food in 2000. This guidance from the EFSA Panel on Nutrition, Novel Foods and Food Allergens provides an updated framework for UL assessments. A draft was published in 2022 and underwent a 2-year piloting period. The present document incorporates revisions based on the experience gained through its practical implementation. It covers aspects related to the planning of the risk assessment (problem formulation and definition of methods) and its implementation (evidence retrieval, appraisal, synthesis, integration, uncertainty analysis). As in the previous framework, the general principles developed for the risk assessment of chemicals in food are applied, i.e. hazard identification, hazard characterisation, intake assessment, risk characterisation. Specific to nutrients are their biochemical and physiological roles and the specific and selective mechanisms that maintain the systemic homeostasis and accumulation of the nutrient in the body. Such considerations must also be taken into account when conducting risk assessments of nutrients.