Ammonia Concentration Research Articles

Impact of thermal hydrolysis on VFA-based carbon source production from fermentation of sludge and digestate for denitrification: experimentation and upscaling implications

Stricter nutrient discharge limits at wastewater treatment plants (WWTPs) are increasing the demand for external carbon sources for denitrification, especially at cold temperatures. Production of carbon sources at WWTP by fermentation of sewage sludge often results in low yields of soluble carbon and volatile fatty acids (VFA) and high biogas losses, limiting its feasibility for full-scale application. This study investigated the overall impact of thermal hydrolysis pre-treatment (THP) on the production of VFA for denitrification through the fermentation of municipal sludge and digestate. Fermentation products and yields, denitrification efficiency and potential impacts on methane yield in the downstream process after carbon source separation were evaluated. Fermentation of THP substrates resulted in 37–70 % higher soluble chemical oxygen demand (sCOD) concentrations than fermentation of untreated substrates but did not significantly affect VFA yield after fermentation. Nevertheless, THP had a positive impact on the denitrification rates and on the methane yields of the residual solid fraction in all experiments. Among the different carbon sources tested, the one produced from the fermentation of THP-digestate showed an overall better potential as a carbon source than other substrates (e.g. sludge). It obtained a relatively high carbon solubilisation degree (39 %) and higher concentrations of sCOD (19 g sCOD/L) and VFA (9.8 g VFACOD/L), which resulted in a higher denitrification rate (8.77 mg NOx-N/g VSS∙h). After the separation of the carbon source, the solid phase from this sample produced a methane yield of 101 mL CH4/g VS. Furthermore, fermentation of a 50:50 mixture of THP-substrate and raw sludge produced also resulted in a high VFA yield (283 g VFACOD/kg VSin) and denitrification rate of 8.74 mg NOx-N/g VSS∙h, indicating a potential for reduced treatment volumes. Calculations based on a full-scale WWTP (Käppala, Stockholm) demonstrated that the carbon sources produced could replace fossil-based methanol and meet the nitrogen effluent limit (6 mg/L) despite their ammonium content. Fermentation of 50–63 % of the available sludge at Käppala WWTP in 2028 could produce enough carbon source to replace methanol, with only an 8–20 % reduction in methane production, depending on the production process. Additionally, digestate production would be sufficient to generate 81 % of the required carbon source while also increasing methane production by 5 % if a portion of the solid residues were recirculated to the digester.

Long-term contamination of decabromodiphenyl ether reduces sediment multifunctionality: Insights from nutrient cycling, microbial ecological clusters, and microbial co-occurrence patterns

Despite the widespread detection of polybrominated diphenyl ethers in aquatic ecosystems, their long-term effects on sediment multifunctionality remain unclear. Herein, a 360-day microcosm experiment was conducted to investigate how decabromodiphenyl ether (BDE-209) contamination at different levels (0.2, 2, and 20 mg/kg dry weight) affects sediment multifunctionality, focusing on carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) cycling. Results showed that BDE-209 significantly increased sediment total organic carbon, nitrate, ammonium, available phosphorus, and sulfide concentrations, but decreased sulfate. Additionally, BDE-209 significantly altered key enzyme activities related to nutrient cycling. Bacterial community dissimilarity was positively correlated with nutrient variability. Long-term BDE-209 exposure inhibited C degradation, P transport and regulation, and most N metabolic pathways, but enhanced C fixation, methanogenesis, organic P mineralization, inorganic P solubilization, and dissimilatory sulfate reduction pathways. These changes were mainly regulated by microbial ecological clusters and keystone taxa. Overall, sediment multifunctionality declined under BDE-209 stress, primarily related to microbial co-occurrence network complexity and ecological cluster diversity. Interestingly, sediment C and N cycling had greater impacts on multifunctionality than P and S cycling. This study provides crucial insights into the key factors altering multifunctionality in contaminated sediments, which will aid pollution control and mitigation in aquatic ecosystems.

The structure of water-ammonia mixtures from classical and abinitio molecular dynamics.

The structure of aqueous ammonia solutions is investigated through classical molecular dynamics (MD) and abinitio molecular dynamics (AIMD) simulations. We have preliminarily compared three well-known classical force fields for liquid water (SPC, SPC/E, and TIP4P) in order to identify the most accurate one in reproducing AIMD results obtained at the Generalized Gradient Approximation (GGA) and meta-GGA levels of theory. Liquid ammonia has been simulated by implementing an optimized force field recently developed by Chettiyankandy et al. [Fluid Phase Equilib. 511, 112507 (2020)]. Analysis of the radial distribution functions for different ammonia concentrations reveals that the three water force fields provide comparable estimates of the mixture structure, with the SPC/E performing slightly better. Although a fairly good agreement between MD and AIMD is observed for conditions close to the equimolarity, at lower ammonia concentrations, important discrepancies arise, with classical force fields underestimating the number and strength of H-bonds between water molecules and between water and ammonia moieties. Here, we prove that these drawbacks are rooted in a poor sampling of the configurational space spanned by the hydrogen atoms lying in the H-bonds of H2O⋯H2O and, more critically, H2O⋯NH3 neighbors due to the lack of polarization and charge transfer terms. This way, non-polarizable classical force fields underestimate the proton affinity of the nitrogen atom of ammonia in aqueous solutions, which plays a key role under realistic dilute ammonia conditions. Our results witness the need for developing more suited polarizable models that are able to take into account these effects properly.

Study of Seasonal Variations in the Physical-chemical Features of the Cauvery Estuary, Southeast Coast of India

Water is a vital element of the environment, supporting life on Earth and being necessary for all living creatures to live. Between rivers and the ocean, estuaries are places with distinctive ecological traits, an abundance of flora and fauna, and a crucial role in hydrological processes and biodiversity. The biological and physico-chemical aspects of aquatic habitats are intertwined. Investigating seasonal fluctuations in the physico-chemical characterisation of the east coast Cauvery estuary in Tamil Nadu is the goal of the current study. The Cauvery Estuary’s physical and chemical properties are known and have an effect on the estuary. Seasonal fluctuations in the climatic and physico-chemical parameters pH, DO, ammonium, nitrate, BOD, sodium, chloride, sulfate, and fluoride content were noted in the waters of the Cauvery estuary. In the future, research on the ecology, biodiversity, and cultural aspects of the estuary species, as well as the determination of the permissible limit for fisheries and aquatic life, may benefit greatly from the initial data on the physical and chemical properties of the Cauvery estuary. In order to protect the Cauvery Estuary, conservation initiatives are started in collaboration with local non-governmental organizations after a thorough understanding of the various factors influencing these ecosystems is obtained.

Способ улучшения зоогигиенических условий выращивания цыплят-бройлеров

Abstract. The purpose of the study is to study the effect of bedding material on the physiological parameters of broiler chickens. Since the most important condition for optimizing the microclimate in the poultry house is compliance with the physiological state of the livestock and maintaining its vital activity at an optimal level. Research methods. The experiment was carried out in the industrial conditions of a poultry farm on broiler stock of the Arbor Acres+ cross in the experimental workshop, where four sections were formed. The growth and development of broilers was monitored daily, livestock records were carried out, and a weekly veterinary report was compiled on the causes of mortality. Also, laboratory studies were carried out according to approved methods for the following indicators: ammonia content, sanitary and hygienic indicators of bedding material, volume, weight and moisture content of bedding material, as well as productivity and basic blood parameters of broiler chickens. Results. Trends in the positive effect of the sorbent in the form of modified diatomite on the productivity of broiler chickens due to the improvement of zoohygienic growing conditions have been identified. In particular, the content of the total number of microorganisms, mold spores and ammonia content in the production experimental workshop is examined in detail. During the work, the volume and weight of bedding material was calculated, including at the exit from the poultry house. We tried to pay special attention to blood biochemistry, which made it possible to assess the physiological state of broiler chickens and draw conclusions about the quality of feeding rations. At the same time, problematic issues associated with feeding poultry were identified, which affect the content of mineral elements in the blood. When determining the performance criterion, calculations were carried out using the EPEF index. Scientific novelty. For the first time, it was proven that the use of diatomite with a bulk layer height of 0.5–1 cm with a granule size of at least 5 mm as bedding material leads to improved zoohygienic conditions for raising broiler chickens without additional capital investments in the form of installation of expensive ventilation equipment or the use of additional technological operations. This replacement option has a positive effect on the health of young poultry.

The Seasonal Characterization and Temporal Evolution of Nitrogen, Phosphorus and Potassium in the Surface and Groundwater of an Agricultural Hydrographic Basin in the Midwestern Brazilian Savanna

The Brazilian savanna (Cerrado Biome) is one of the most important regions in the world in terms of food production, with the use of fertilizers based on nitrogen, phosphorus and potassium (NPK). When not applied properly, fertilizers can alter and affect water quality. The objective of this study was to evaluate the presence of these compounds in surface and groundwater in the Upper Jardim River Hydrographic Unit, Federal District, thus characterizing seasonal variations during the dry and rainy seasons in two periods. A total of 207 groundwater samples and 23 surface water samples were collected in the years 2014, 2015, 2019 and 2020. The parameters analyzed were pH and nitrate, nitrite, ammonium, phosphate and potassium ions. In groundwater samples, pH values were significantly higher and ion levels lower in samples collected during the early years (except for nitrate), and the ammonium concentrations were lower in the dry season than the rainy (in 2014 and 2019). In surface samples, total phosphorus levels were significantly higher in the rainy/2019 compared to the rainy/2020 season, while this tendency was inverted for potassium during the dry season. The use of NPK-based fertilizers has increased considerably in recent years in the region due to the expansion of the agricultural area, and although the results of the study show that concentrations in water are much lower than the maximum values allowed by Brazilian legislation, continuous monitoring is necessary to guarantee water quality.

Free Ammonia Strategy for Nitrite-Oxidizing Bacteria (NOB) Suppression in Mainstream Nitritation Start-Up

The partial nitritation (PN)–anammox (PN/A) process offers a sustainable alternative to nitrogen management in wastewater treatment, addressing the high costs and increasing the low eco-friendliness associated with traditional nitrification/denitrification processes. Stable partial nitritation (PN) is critical for effective PN/A operation, and this study specifically focused on the need to suppress nitrite-oxidizing bacteria (NOB) to facilitate the enrichment of ammonia-oxidizing bacteria (AOB). Utilizing two sequencing batch reactors (SBRs), PN1 and PN2 with different free ammonia (FA) concentrations, this study aimed to evaluate the NOB suppression strategy while enriching AOB. The PN2 reactor, which operated with a higher initial FA concentration (50 mg/L), successfully maintained high nitritation activity, with 96.1% ammonium removal efficiency (ARE) and 95.1% nitrite accumulation efficiency (NAE) at reduced influent NH4+-N concentrations (50 mg NH4+-N/L, FA 10 mg/L). In contrast, PN1 showed inadequate NOB suppression due to lower FA concentrations (10 mg/L). These results suggest that initiating the nitritation process with higher FA concentrations can effectively suppress NOB, enhancing the stability and efficiency of PN/A processes in mainstream applications.

Investigation of the Effects of Erzurum Province Wastewater Treatment Plant on the Karasu River Water Quality

This study was carried out to investigate the effects of the wastewater treatment plant located in the Aziziye District of Erzurum Province on the Karasu River. For this purpose, water samples were taken from 3 stations for a year between 2022-2023. The mean water temperature was measured in situ during sampling as 13.8 ˚C, the mean pH value was 7.7, the mean electrical conductivity was 403 µs/cm, and the mean dissolved oxygen value was 6 mg/l. The mean total suspended solid (TSS) amount was determined as 46.7 mg/l, the mean chemical oxygen demand (COD) concentration was 28.9 mg/l, the mean biological oxygen demand (BOD) concentration was 18.5 mg/l, the mean total nitrogen (TN) concentration was 4.47 mg/l, the mean nitrate (NO3) concentration was 5.35 mg/l, the mean nitrate nitrogen (NO3-N) concentration was 1.21 mg/l, the mean total hardness (TH) was 155 mg/l, the mean ammonium (NH4) concentration was 2.75 mg/l, and the mean ammonium nitrogen (NH4-N) concentration was 2.16 mg/L. As a result, it was determined that the Wastewater Treatment Plant positively affected some water quality parameter values of the Karasu River.

Assembly process and co-occurrence network of microbial community in response to free ammonia gradient distribution.

The research presented in this paper explores how varying concentrations of free ammonia impact microbial communities in aquatic ecosystems. By employing advanced gene sequencing techniques, the study reveals significant changes in microbial diversity and network structures in response to increased ammonia levels. Key findings indicate that high ammonia concentrations lead to a decrease in microbial richness and diversity while increasing community dissimilarity. Notably, certain microbial groups, like Actinobacteria, show resilience to ammonia stress. This research enhances our understanding of how pollution affects microbial ecosystems and underscores the importance of maintaining balanced ammonia levels to preserve microbial diversity and ecosystem health.

Nitrogen fate in riparian zones: Insights from experiments and analysis of sediment porosity and surface water-groundwater exchange

Riparian zones play a vital role in the river ecosystem. Solutes in vertical riparian zones are transported being by alternating hydraulic gradients between river water and groundwater, due to natural or human activities. This study investigates the impacts of porous sediments and alternating rate of surface water-groundwater on nitrogen removal in the riparian zone through experiments based on the field sampled. The experimental results, combined with dimensionless numbers (Péclet and Damköhler) and Partial Least Squares-Path Modeling, analyze the nitrogen fate responding to hydrodynamics changes. The results show that increased sediment porosity contributes to the ammonium removal, particularly when the oxygen content of river water is low, with the removal rate up to 72.57%. High ammonium content and dissolved organic carbon (DOC) in rural rivers lead to a constant low-oxygen condition (4 mg/L) during surface water-groundwater alternation, and promote denitrification. This threatens groundwater with ammonium pollution and causes accumulation at the top of vertical riparian zones during upwelling, potentially causing secondary river pollution. However, increasing the alternating rate hinders the nitrate denitrification and drastically changes in the redox environment of the riparian zone, despite contributing to ammonium removal. Rapid oxygen consumption during aerobic metabolism and nitrification in groundwater-surface water exchange created favorable conditions for denitrification. Floodplains sediment porosity is unfavorable for nitrification. This study improves understanding of coupled hydrologic and solute processes in vertical riparian zones, informing strategies for optimizing nitrogen attenuation and riparian zone construction.

Role of Nitrifiers Associated with Mangrove clam Polymesoda Erosa in Bioremediation.

Polymesoda erosa is a mangrove clam known for its water filtration ability. This clam was investigated for its bioremediation potential and growth in synthetic wastewater during 40 days of incubation. Variation in the nutrient composition of water, biochemical composition of the clams, and metagenomic analysis of the microorganisms associated with clam tissue were carried out. Significant differences in the concentration of ammonia (p ≤ 0.01), nitrite (p ≤ 0.001), and nitrate (p ≤ 0.05) in the wastewater were observed between day 0 and day 40. A reduction of approximately 89% in ammonia concentration at the end of the experiment was recorded indicating nitrification activity. However, biochemical parameters showed negligible differences before and after the incubation experiment. Thus suggesting that the chemosynthetic-based nutrition aids in the survival of the clam as no organic matter was added to the medium. The substantial decline in levels of ammonia in the presence of clams as compared to its absence suggests the significant role of clams in improving the water quality. Furthermore, the metagenomic analysis of the gill tissue of P. erosa revealed ~ 50% of the microbial population to consist of nitrifiers. The study highlights the contribution by the nitrifers associated with the clams not only to its growth and resilience but also to bioremediation.

Energy and exergy optimization of Kalina Cycle System-34 with detailed analysis of cycle parameters

This study proposes a novel methodology for optimizing the Kalina Cycle System-34, providing new insights into the existing literature on the cycle. The research highlights the cycle's key variables and identifies the most critical parameters that require improvement while proposing a practical and effective optimization method. The effects of parameters on thermal and exergy efficiency were quantified using Taguchi and ANOVA methods. The study focuses on critical parameters such as evaporator outlet temperature, turbine inlet pressure, ammonia concentration, turbine efficiency, and pump efficiency. The optimal values of these parameters were determined within specified ranges. Furthermore, the study employed the L25 orthogonal array to create case scenarios that reduced the computational cost of the Kalina cycle. The best-case scenario was not included in the 25 cases in the orthogonal array, which significantly reduced computational costs. The results showed that the system's thermal efficiency increased to 16.2 %, and exergy efficiency increased to 27.8 %, with the case conditions for the best case being an evaporator outlet temperature of 120 °C, ammonia concentration of 0.9, turbine inlet pressure of 40 bar, turbine efficiency of 0.9, and pump efficiency of 0.8.

Phenotypic traits related to methane emissions from Holstein dairy cows challenged by low or high forage proportion

Limited literature is available identifying phenotypical traits related to enteric methane (CH4) production from dairy cows, despite its relevance in relation to breeding for animals with a low CH4 yield (g/kg DMI), and the derived consequences hereof. This study aimed to investigate the relationships between CH4 yield and different animal phenotypes when 16 2nd parity dairy cows, fitted with a ruminal cannula, were fed 2 diets differing in forage:concentrate ratio in a crossover design. The diets had either a low forage proportion (35% on DM basis, F35) or a high forage proportion (63% on DM basis, F63). Gas exchange was measured by means of indirect calorimetry. Spot samples of feces were collected, and indigestible NDF (INDF) was used as an internal marker to determine total-tract digestibility. In addition, ruminal evacuations, monitoring of chewing activity, determination of ruminal VFA concentration, analysis of relative abundance of methanogens, and measurement of liquid passage rate were performed. Statistical differences were analyzed by a linear mixed model with diet, days in milk, and period as fixed effects, and cow as random effect. The random cow estimates (RCE) were extracted from the model to get the Pearson correlations (r) between RCE of CH4 yield with RCE of all other variables measured, to identify possible phenotypes related to CH4 yield. Significant correlations were observed between RCE of CH4 yield and RCE of OM digestibility (r = 0.63) and ruminal concentration of valeric acid (r = -0.61), acetic acid (r = 0.54), ammonium (r = 0.55), and lactic acid (r = ‒0.53). Additionally, tendencies were observed for correlations between RCE of CH4 yield and RCE of H2 yield in g/kg DM (r = 0.47, P = 0.07), and ruminal isobutyric acid concentration (r = 0.43, P = 0.09). No correlations were observed between RCE of CH4 yield and RCE of ruminal pool sizes, milk data, urinary measurements, or chewing activity. Cows had a lower DMI and ECM, when they were fed F63 compared with F35. Cows fed F63 had higher NDF digestibility, CH4 emissions (g/d, g/kg of DMI, and g/kg of ECM), ruminal concentration of acetic acid, ruminal pH, degradation rate of digestible NDF (DNDF, %/h), and longer rumen retention time (h). Also, rumination and total chewing time (min/kg DMI) were higher for cows fed F63. The results in the present study emphasize the positive relation between cow's ability to digest OM and their CH4 emissions. The derived consequences of breeding for lower CH4 emission might be cows with lower ability to digest OM, but more studies are warranted for further documentation of this relationship.

20-year water quality analysis reveals spatial variability and long-term changes at North Carolina's Masonboro Island National Estuarine Research Reserve

Urbanization impacts, especially stormwater runoff and pollutant discharge, pose ecological threats to coastal ecosystems globally. Long-term environmental monitoring datasets and assessments are used to quantify anthropogenic impacts on ecosystem health. This study synthesized twenty years (2002–2021) of water quality data from the National Estuarine Research Reserve System-wide Monitoring Program at the understudied Masonboro Island Reserve (North Carolina, United States) and provided an analytical methodology that can be applied to other Reserves and monitoring programs world-wide. Time series and correlation analyses of biological, chemical, and physical water quality parameters were used to identify spatiotemporal trends of nutrient dynamics and phytoplankton biomass at three stations within a 5-km stretch of the Atlantic Intracoastal Waterway. Heterogenous water quality conditions were observed between stations, especially for chlorophyll a, and were influenced by the relative proximity to marine waters, human developments, and urban tidal creeks. Long-term trends indicated significant water quality changes (i.e., increased chlorophyll a, reduced pH and salinity) related to anthropogenic influences. An unexpected and rapid shift in nutrient dynamics occurred around 2007, marked by significantly decreased ammonium and orthophosphate concentrations, which considerably reduced DIN/DIP ratios. This positive change was potentially influenced by sewage infrastructure improvements and stormwater wetland construction, removing waste-derived nutrients that previously entered the ecosystem. Impacts of major storms were also observed with weeks of hypoxia and low salinity following Hurricane Florence. These findings emphasized the value of long-term trend analyses of monitoring program data at multiple sites and provided insights into the significant water quality impacts of urbanization and benefits from wetland protection. This study further encourages the evaluation of long-term water quality monitoring datasets in estuarine environments globally.

Evaluation of black tilapia (Oreochromis niloticus) hatchery in UPT-Perikanan Budidaya Air Tawar (PBAT) Sukorejo, Malang

Abstract Black tilapia is a freshwater fish that has become a leading commodity in the UPT-PBAT (Unit Pelayanan Teknis-Pengembangan Budidaya Air Tawar) Sukorejo Freshwater Aquaculture Fisheries with an optimal selling price. The purpose of this study was to evaluate the hatcheries activity performance in UPT-PBAT Sukorejo. The method in this research used active participation and descriptive methods. The data collection method used was from primary and secondary data. Primary data taken in this study were fertilization rate, hatching rate, and survival rate while secondary data was from literature comparison and asking directly to the staffs of UPT-PBAT Sukorejo. The results of hatchery performance showed fertilization rate of 95%, hatching rate of 98.6%, and survival rate of 93%. Hatching was carried out naturally using a 1:3 ratio (50 male fish and 150 female fish per pond). The research results indicated that hatchery activity in UPT-Freshwater Aquaculture (PBAT) Sukorejo, Malang showed good performance. However, water quality (ammonia) needs more attention to prevent negative effect in the next aquaculture cycle activity since this study found the ammonia value reached minimum tolerable value. Ammonia that exceeds the limit can cause mortality to black tilapia. Changing water is important to avoid mortality due to high ammonia content.

Exploring the Effects of Different Processing Techniques on the Antitussive Expectorant of Platycodon grandiflorus by Metabonomics and Pharmacologic Methods

Background and Purpose Platycodon grandiflorum is a traditional Chinese herbal medicine, which can disperse lung, promote pharynx, dispel phlegm and expel pus. Its processing history was first seen in the “Zhou Hou Bei Ji Fang” of the Jin Dynasty in China. Through processing, effective substances in plants can be enriched and negative substances can be reduced. Therefore, this study explored the effects of different processing methods on the antitussive and expectorant effects of Platycodon grandiflorum through metabolomics and pharmacology, aiming to provide a theoretical basis for clinical application. Experimental Approach The changes of metabolites before and after processing of Platycodon grandiflorum were analyzed by Nexera UHPLC LC-30A-HILIC-Orbitrap-Q Exactive HF-X platform. The antitussive and expectorant effects of processed Platycodon grandiflorum were verified by mouse concentrated ammonia induced cough method and tracheal phenol red drainage method. Key Results After processing, some metabolites of Platycodon grandiflorum changed, among which 24 kinds of terpenoid metabolites changed significantly. Through the experiment of ammonia-induced cough in mice and phenol red expectorant experiment, it was found that fresh JZI 40%, fresh CZ 80%, dry JZZ 40% and dry JZI 80% had obvious antitussive effect, and dry JZZ 40% had obvious expectorant effect. Conclusions and Implications Some processing methods can indeed further improve the antitussive and expectorant effects of Platycodon grandiflorum, which may be due to the effect of increasing the content of triterpenoids after processing, but the mechanism of processing to improve the effect of relieving cough and expectorant needs further study.

Non-thermal plasma-catalytic ammonia synthesis over alumina-supported iron catalyst: Insights into the effect of alumina calcination temperature

Non-thermal plasma-catalytic ammonia synthesis (NTPCAS) has been regarded as a promising route to store hydrogen by utilizing renewable electricity. Alumina is a suitable support of the catalysts in NTPCAS and its properties can influence the performance of catalysts remarkably. In this study, the influence of the alumina calcination temperatures (Tc) on the catalytic performance of Fe-Al-x (x represents the value of Tc) was analyzed in a dielectric barrier discharge (DBD) reactor for NTPCAS. The results suggested that an increase in Tc transforms the alumina crystalline from γ phase to α phase. The best performance with a synthesized ammonia concentration of 11833 ppm was achieved over Fe-Al-900 with coexisting γ and θ phases of alumina under N2: H2 = 1:1 and SEI = 37.05 kJ/L conditions, which was 37 % higher than that of Fe-Al-800 with only γ phase. In addition, the larger Tc (i.e. 1100 and 1200 °C) decreased the specific surface area, increased the mean catalyst particle size, and led to the non-uniform dispersion of Fe species. The NH3-TPD and XPS studies suggested that an increase in Tc could influence the surface acidity and oxygen vacancy concentration of Fe catalysts, which were crucial to adjusting the catalytic activity for NTPCAS. This study clarifies the value of a suitable design of support of catalysts for improving NTPCAS.

МИКРОВОДОРОСЛИ ХЛОРЕЛЛА ДЛЯ ОЧИСТКИ СТОКОВ В СЕЛЬСКОМ ХОЗЯЙСТВЕ

A promising way to solve current problems of energy saving and reducing environmental pollution may be the use of microalgae. These simple microorganisms are capable of purifying contaminated wastewater in agriculture. Wastewater contains nitrogen, phosphorus, sulfate and other contaminants. In order to optimize the technology of obtaining biodiesel fuel from lipid components in the conditions of small agricultural producers, the possibility of using Chlorella vulgaris in cleaning from ammonium ions and phosphate ions was studied. Chlorella was cultivated in a photobioreactor on a standard Tamiya medium and wastewater for 10 days at a temperature of 30 ° C and an illumination of 14 kLx in the red (620-740 nm), blue (430-500 nm) and green (500-565 nm) wavelength ranges. The filtrate of the microalgae suspension was collected over several days and assessed for the content of phosphate and nitrate ions using a photometric method. The greatest increase was observed with illumination in the red range (2 times higher), the minimum value in the green. The studies found that cell growth occurs both in synthetic, standard nutrient media and in wastewater, the latter being more costeffective. It was found that when adding chlorella to wastewater, the maximum decrease in the content of ammonium ions and phosphate anions is observed on the 6-7th day (by 19-59% and 5-29%, respectively), which is most likely due to the use of these elements by microalgae for nutrition and maintenance of life. A scheme for growing Chlorella vulgaris on wastewater for further production of lipid components of biodiesel fuel is proposed.

Using the Taguchi Method and Grey Relational Analysis to Optimize Ventilation Systems for Rural Outdoor Toilets in the Post-Pandemic Era

This study addresses the issue of poor air quality and thermal comfort in rural outdoor toilets by proposing a ventilation system powered by a building-applied photovoltaic (BAPV) roof. A numerical model is established and validated through comparison with the literature and experimental data. Based on a consensus, four influential variables, namely, inlet position, outlet height, supply air temperature, and ventilation rate, are selected for optimization to achieve multiple objectives: reduction in ammonia concentration, a predicted mean vote (PMV) value of 0, minimization of age of air, and energy consumption. The present study represents a pioneering effort in integrating the Taguchi method, computational fluid dynamics (CFD), and grey relational analysis to concurrently optimize the influential variables for outdoor toilet ventilation systems through design and simulation. The results indicate that all four variables exhibit nearly equal importance. Ventilation rate demonstrates a dominant effect on ammonia concentration and significantly impacts the age of air and energy consumption, while supply air temperature noticeably influences PMV. The optimal scheme features an inlet at center top position, an outlet height of 0.2 m, a supply air temperature of 12 °C and a ventilation rate of 20 times/h. This scheme improves ammonia concentration by 18.9%, PMV by 6.8%, and age of air by 30.0% at a height of 0.5 m, while achieving respective improvements by 18.9%, 5.5%, and 22.2% at a height of 1.5 m. The BAPV roof system generates an annual electricity output of 582.02 kWh, which covers the energy consumption of 358.1 kWh for toilet ventilation, achieving self-sufficiency. This study aims to develop a zero-carbon solution for outdoor toilets that provides a safe, comfortable, and sanitary environment.

Tracing nitrogen and phosphorus pollution in urban runoff: Insights from isotopic tracers and SWMM modeling

Water contamination in certain rivers during rainfall necessitates the evaluation of pollutant levels within pipelines and the identification of their sources to ensure effective pollution control. In this study, we assess pollutant concentrations during runoff from surfaces, pipelines, and channels, identify pollutant sources within pipelines, and analyze sewage leakage contributions to channel pollution in residential areas in Wuxi City, China. The results showed that the event mean concentrations of total nitrogen (TN), total phosphorus (TP), ammonium (NH4+-N), and nitrate (NO3−-N) in the drainage outlet runoff were 3.4, 1.1, 8.8, and 14.9 times higher than in impervious surface runoff. The predominant forms of nitrogen and phosphorus in runoff shift from organic to inorganic as they move from the surface to pipelines. The pipeline load and contribution were further estimated by combining water quantity calculations from the calibrated and verified Storm Water Management Model (SWMM) with measured nitrogen and phosphorus concentrations in the runoff. TN, NH4+-N, NO3−-N, and PO43--P within the pipelines accounted for 59%, 83%, 90%, and 77% of the discharge loads, respectively. The application of the Stable Isotope Analysis in R (SIAR) package (MixSIAR) revealed that the domestic sewage and soil organic N were the predominant sources of pollutants within drainage pipelines, contributing 23.7% and 32.6% of NO3−-N, respectively. Additionally, the sewage leakage accounted for 33.7% and 66.9% of NO3−-N in drainage runoff and channels, respectively. Unlike existing methods, this study quantitatively highlights the significant impact of pipeline pollutants and sewage leakage on urban river water quality, providing essential insights for developing effective strategies to mitigate non-point source water pollution.