Amount Of Ammonia Research Articles

Point-of-Care-Testing NO3-N Detection Technology with Selected Transition-Metal-Based Colorimetric Sensor Arrays.

Nitrate-nitrogen (NO3-N) is a major contaminant in groundwater and seawater. Significant amounts of ammonia are oxidized to nitrate through nitrification, leading to an imbalance in the nitrogen cycle and causing nitrate pollution in water bodies. Controlling NO3-N levels is a significant challenge for both marine aquaculture and human health. Traditional measurement methods, such as ion chromatography and continuous flow analysis, require pretreatment steps to detect NO3-N in complex matrices, which is time-consuming. However, in this study, we developed a transition-metal-based sensor capable of measuring NO3-N concentrations on-site without the need for pretreatment. We analyzed the color change of transition-metal-based sensors over time and obtained color data by mixing transition metals (Mn, V, Fe, Co, Cr, Cu, and Ni) with solvents and additives at fixed ratios, and combining them with standard solutions of NO3-N at concentrations of 1, 2, 3, 5, 10, 20, 30, 40, 50, 75, and 100 ppm. We selected sensors that exhibited linearly increasing color velocity with increasing NO3-N concentrations and developed an array sensor using the selected sensors. The performance of the array was validated by comparing its results with those of hierarchical cluster analysis (HCA) based on color data and compositional analysis, confirming its ability to detect NO3-N in complex matrices. Additionally, by creating a large data set of color change patterns of the array sensor, we can develop selective array sensors for detecting specific substances, surpassing the capability of merely measuring the NO3-N concentration.

In situ characterization of amine‐forming enzymes shows altered oligomeric state

AbstractEnzyme stability can be measured in a number of ways, including melting temperature, activity retention, and size analysis. However, these measurements are often conducted in an idealized storage buffer and not in the relevant enzymatic reaction media. Particularly for reactions that occur in alkaline, volatile, and high ionic strength media, typical analyses using differential scanning calorimetry, light scattering, and sodium dodecyl‐sulfate polyacrylamide gel electrophoresis are not satisfactory to track the stability of these enzymes. In this work, we monitor the stability of engineered and native dehydrogenases that require a high amount of ammonia for their reaction to occur. We demonstrate the benefits of analyzing these enzymes in their reaction buffer, uncovering trends that were not observable in the typical phosphate storage buffer. This work provides a framework for analyzing the stability of many other enzymes whose reaction media is not suitable for traditional techniques. We introduce several strategies for measuring the melting temperature, oligomeric state, and activity of these enzymes in their reaction media. Further, we have identified opportunities for integration of computational tools into this workflow to engineer enzymes more effectively for solvent tolerance and improved stability.

Comparison of Ammonia Removal from Ground Water in Attached Growth Process Using Over-burnt Brick with Suspended Growth Process without Any Media

Rising amount of ammonia in groundwater is rising problem in groundwater of Kathmandu. This has led to various diseases like blue baby syndrome to arise. So, it is necessary for efficient and safe removal of ammonia from drinking water. Since the physical-chemical system includes the major disadvantages of high operation and maintenance cost, the biological nitrification system can only be a good alternative to remove ammonia from ground water. Hence, an attempt is done in this research to treat ammonia contaminated water by biological nitrification process. Three reactors were constructed in series with media of over-burnt brick and other three in series were constructed without media. The study was carried out for five different flow rates of 10, 14.4, 18.8, 27.6 and 38.8 ml/min. Based on laboratory test the efficiency of these five different flow rates was plotted and conclusions were reached. Achievement of continuously increasing efficiency, which reached to 95–100% in the reactor provided with over-burnt media; reflects a success in the assumption that the over-burnt brick is good media to be used in bio filters for nitrification. The reactors with media have more efficiency than reactors without media. An average efficiency of 56.48% for reactors with media and 37.55% for reactors without media was observed for all the flows. The difference of 18.72± 0.2 was found between reactor with media and reactor without media in both series and single reactor. Low flow rates showed better ammonia removal than flow rates with higher flow rates such that a hydraulic retention time of 7.29 hour per reactor can be taken as design criteria for nitrification using over-burnt brick as media.

Effects of perfluoroalkyl acids on nitrogen release, transformation and microbial community during the debris decomposition of Alisma orientale and Iris pseudacorus

The release of nutrients into water during debris decomposition is a serious concern, leading to severe environmental pollution. To understand the effects of extensively present emerging contaminants (such as perfluoroalkyl acids (PFAAs)) on the nitrogen (N) release and transformation, the concentration dynamics of different N species in surrounding water and changes in microbial communities on biofilm during the 70-days decomposition of two typical submerged macrophyte (Alisma orientale and Iris pseudacorus) debris were studied. The results showed that large amounts of N species (especially organic and ammonium N) were released during decomposition. PFAAs with a low concentration (1 μg/L) could stimulate total N (TN) release, whereas PFAAs with a high concentration (≥ 10 μg/L) might have inhibited TN release. Higher intensities of ammonification, nitrosification, and denitrification, but lower intensities of nitrification were observed in water in the presence of PFAAs. Microbiota associated with organic matter hydrolysis, nitrification and denitrification, as well as PFAA degrading/tolerant bacteria, were beneficial and might have occupied dominant states. Redundancy analysis showed that PFAAs were positively associated with the amounts of nitrate, denitrifiers, and azotobacteria but negatively correlated with the TN, ammonia, nitrite, organic N, and nitrosobacteria amounts (p = 0.0002). The complete N metabolism pathway was identified using PICRUSt and KEGG. Functional genes related to ammonification (0.76‰–2.16‰), N reduction (3.43‰–5.05‰), and assimilation (0.81‰–2.16‰) were more abundant than others in all treatments. This study provides a more comprehensive understanding of N cycling during debris decomposition under the increasingly intractable threat of emerging contaminants in aquatic ecosystems.

Synergistic Effect of Influence Factors on Ammonia Volatilization in Fertilizer Solution: A Laboratory Experiment

Ammonia volatilization, which is one of the main ways that nitrogen gas is released from farmland, restricts promotion of the utilization of nitrogen fertilizer and contains some potential environmental risks. To investigate the general pattern of ammonia volatilization under actual paddy field conditions, we designed an indoor simulated system to measure the amount of ammonia volatilized within a single time period by controlling the pH and concentration of NH4+ (c(NH4+)) in the solution, the gas–liquid interfacial gas velocity, and the ambient temperature. In this paper, the influence of these factors, the synergistic effect on ammonia volatilization, and their quantitative relationship are discussed. We used solutions of ammonium bicarbonate (SAB) and diammonium phosphate (SDP) for the simulation experiments, and the results showed that there is a significant linear relationship between the amount of ammonia volatilization and c(NH4+). The correlation coefficients were between 0.9214 to 0.9897 and 0.8932 to 0.9904 for SAB and SDP, respectively. The quantitative relationship between temperature and pH and the influence factor (CIF) and the initial ammonia volatilization fluxes (IAVFs) was analyzed by the least-squares method, and the degrees of polynomial were one and two, respectively. The regression equations of the SAB and SDP among the amount of ammonia volatilization with the concentration of ammonium nitrogen, the temperature, and the pH were calculated by using MATLAB. Considering the effects of temperature and pH on the CIF and IAVFs under individual conditions, we used a binary cubic model to fit the relationship between temperature and pH to the CIF and IAVFs. The simulation results showed that the correlation coefficients between the CIF and IAVFs for SAB were 0.9980 and 0.9680, respectively, and the correlation coefficients were 0.9946 and 0.9708 for SDP, respectively. The quantitative equation took into account the coefficient of determination and degrees of polynomial, and the ammonia volatilization fluxes can be calculated by using these equations.

A new process for preparing ultrafine WC-Co cemented carbide by doping yttrium within the ammonium metatungstate solution

Ultrafine WC-Co cemented carbide has superior performance of high strength and high hardness, which is widely used in industrial fields. In the traditional process, high temperature carburization method is used to prepare tungsten carbide, and solid-phase mechanical milling method is used to mix grain growth inhibitor (Cr3C2) and tungsten carbide, which easily lead to large WC particle size and uneven WC grain size distribution in WC-Co cemented carbide, thus affecting mechanical properties of the alloy. In the new process, based on the genetic relationship between the particle size of ammonium paratungstate and tungsten carbide, ultrafine ammonium paratungstate uniformly doped with yttrium was firstly obtained by adding a certain amount of ammonia and yttrium oxide into the ammonium metatungstate solution. Then the ammonium paratungstate was calcined to obtain yttrium-doped tungsten trioxide, which was then converted into yttrium-doped ultrafine tungsten carbide powders by introducing carbon monoxide at a low temperature. Finally, the ultrafine WC-Co cemented carbide was prepared by pressure sintering. During the neutralization and crystallization process of ammonium metatungstate solution, the yttrium-doped ultrafine ammonium paratungstate (Fischer particle size 8.4 μm) with narrow particle size distribution and regular morphology was prepared. The yttrium-doped ammonium paratungstate was calcined at 500 °C for 90 min in air atmosphere to obtain yttrium-doped tungsten trioxide powder with a Fischer particle size of 4.5 μm and narrow size distribution. Then the yttrium-doped tungsten trioxide and carbon monoxide gas were reacted at 920 °C for 3h to obtain yttrium-doped ultrafine tungsten carbide powder with a Fischer particle size of 0.32 μm and a specific surface area of 4.44 m2/g, and ultrafine WC-Co cemented carbide with tungsten carbide grain size of 0.28 μm was obtained by pressure sintering. The yttrium uniform distributed effectively inhibited the abnormal growth of tungsten carbide grains. Compared with the WC-Co cemented carbide prepared by solid-phase mechanically mixing tungsten carbide powder and chromium carbide, the yttrium-doped WC-Co cemented carbide had a smaller average tungsten carbide grain size and a more homogeneous microstructure. The prepared yttrium-doped WC-Co cemented carbide had a hardness (HRA) of 94.6, a bending strength of 4841 M, and a coercive force of 42.3 KA/c.

Experimental and numerical investigation of direct ammonia solid oxide fuel cells with the implementation of ammonia decomposition source terms in a 3D finite volume-based model

Ammonia and fuel cells have become more popular in the past few years. This is directly associated with the prevailing industrial trend toward reducing emissions. Ammonia is a fuel that can be utilized in solid oxide fuel cells (SOFCs). Nevertheless, ammonia-fueled solid oxide fuel cells (DA-SOFCs) are sensitive to the degradation during operation. This study aims to determine the causes of such incidents as using experimental and numerical methods. Investigation of cells with various thicknesses of anode support layers revealed that the cells fracture during long-term operation under a load of 0.125 A cm−2. The OpenFuelCell (OFC) model developed by the author for the DA-SOFC analysis showed a high temperature gradient (up to 70 °C) in the microstructure. It was found that increasing the amount of ammonia supplied to the cell from 33.3 ml min−1 to 50 ml min−1 while maintaining the same fuel utilization increases the difference in temperature by 55 %. Subsequently, it was shown that the presence of ammonia in the anode functional layer (ASL) of the cell is associated with a decrease in DA-SOFC efficiency. The investigation identifies potential areas for improving DA-SOFCs from both the operational and manufacturing point of view and offers a tool for investigating these areas.

Influence of ammonia-water fog formation on ammonia dispersion from a liquid spill

Ammonia is expected to play an important role in the green transition, both as a hydrogen carrier and a zero-emission fuel. The use of refrigerated ammonia is attractive due to its relatively high volumetric energy density and increased safety compared to pressurized solutions. Ammonia is highly toxic, and with new applications and increased global demand come stricter requirements for safe handling. Cold gaseous ammonia following a spill of refrigerated ammonia will in contact with humid air cause fog formation. In an environment rich in ammonia, these droplets will due to ammonia’s strong hygroscopicity consist of considerable amounts of liquid ammonia as well as water. Fog formation affects the ammonia-air density and thus influences the dispersion dynamics, with a potentially significant impact on hazardous zones. In this work, we present a CFD model including an ammonia-water fog formation model based on accurate thermodynamics. This includes modeling the vapor–liquid equilibrium and accounting for the exothermic mixing of ammonia and water. We apply this CFD model to relevant cases and demonstrate the significant impact of the fog. We analyze the effect of varying relative humidity, fog visibility, influence of wind, and pool evaporation rate. Finally, we model the Red Squirrel test 1F and show how the fog formation could have influenced the dispersion behavior.

Solid State Vanadate Laser and 213 nm Rayleigh Rejection Filter Enable Miniaturized Deep Ultraviolet Raman Spectrometers.

A combination of a highly efficient 213 nm Rayleigh rejection filter (RRF) and a miniaturized 213 nm neodymium-doped vanadate laser enables portable deep ultraviolet (UV) Raman spectrometers. We demonstrate the high efficiency of 213 nm RRF manufactured by Green Optics Co., Ltd by utilizing our compact 213 nm vanadate laser to measure high signal-to-noise ratio UV Raman spectra of Teflon and UV resonance Raman (UVRR) spectra of solid ammonium nitrate. We also demonstrate UVRR detection of trace amounts of ammonia formed during ammonium nitrate UV photolysis. We roughly estimate the ammonia UVRR detection limit of ∼10 ng under our experimental conditions.

The Effect of Probiotic Administration with Different Time Intervals on Water Quality in Shrimp Cultivation Vaname (Litopenaeus vannamei) Biofloc System

Vaname shrimp is one of the marine fishery commodities that has high economic value. Water in vaname shrimp cultivation must be maintained in quality. Ammonia can be harmful to shrimp, control of ammonia and organic matter content can be done biologically with the application of probiotics. Therefore, this study needs to be conducted to determine the right time interval in providing probiotics to the water quality of vaname shrimp cultivation in the biofloc system. The method used in this study is the experimental method, using RAL with 4 treatment levels and 3 repetitions, with treatment P0 (Once during maintenance), P1 (once every 5 days), P2 (once every 10 days) and P3 (once every 15 days), the probiotic used in this study is the probiotic Probio-7. The results of the study during 56 days of maintenance showed that the average value of water quality salinity 26.7-27 ppt, temperature 27.7-28°C DO 7.13-7.16 mg/L, nitrate 0.63-0.87 mg/L and Total Ammonia 0.76-0.92 mg/L. Based on the research activities that have been carried out, the interval of probiotic administration has a significant effect on water quality. Probiotic administration can increase the Total Ammonia content and reduce the amount of ammonia in this study. Probiotic administration with an interval of 5 days once (P1) gave a total ammonia value of 0.78 mg/L with an ammonia amount of 0.067 mg/L. P1 also gave the highest growth, absolute weight 5.61 g, absolute length 8.82 cm, SGR 5.779%/Day and FCR 1.47.

Rapid ambient pressure drying preparation of bulk ZrO2-SiO2 aerogels with high thermal stability

In this study, the sol-gel stage co-precursor method was used to hydrophobically modify the gel and increase the content of alkali catalyst in the gel, thereby reducing the capillary force generated during ambient pressure drying and enhancing the strength of the gel skeleton. This improvement makes the gel skeleton structure not easy to destroy during the rapid drying process, thus greatly reducing the preparation time of atmospheric pressure drying, which could be as short as 10 h. It is worth mentioning that this method does not require extensive use of modifiers and organic solvents, so it has low cost, high efficiency, and broad industrial production application prospects. The experimental results show that the DDS/ZSA aerogel exhibits the lowest thermal conductivity (0.035 W m−1 K−1) when the dilute ammonia content is 5 ml. However, it should be noted that too low or too high an amount of dilute ammonia will lead to a decrease in aerogel performance, so it needs to be controlled within the appropriate range. In addition, the prepared aerogel has excellent hydrophobic properties with a contact angle greater than 140° and excellent thermal stability at 1000 °C, which can be used in harsh, humid, and high-temperature environments.

Highly efficient nitrogen-doped graphene coupled eosin-B photocatalyst for fixation and regeneration of N2 and NADH cofactors under visible light

Achieving nitrogen fixation in visible light-driven using metal-free and eco-friendly semiconductors at acceptable temperature and pressure still remains a big challenge. In the field of artificial photosynthesis, reported semiconductors for nitrogen fixation have large band gap around 3.0 eV and requires high temperature and pressure which results the catalytic nitrogen fixation is navigate under visible light, consume supply of global energy, and emit global greenhouse gas. In conflict this report illustrates a metal free catalyst EBCNDG with a band gap of ∼2.64 eV at room temperature and pressure indicate photocatalytic campaign toward nitrogen fixation in visible light without producing any harmful gases. The EBCNDG photocatalyst has a vacancy of high active oxygen which helps adsorb and stabilize the intermediate and increases the rate of nitrogen fixation. The EBCNDG photocatalyst was prepared by coupling of an eosin B (EB) with N-doped graphene (NDG) via amide linkage. This unique combination opens a new trial for nitrogen fixation as well as NADH regeneration under acceptable conditions using visible energy. The amount of ammonia obtained by EBCNDG is 0.513 mM and the regeneration yield of NADH is 90.3%.

Nitrogen removal strategy for real swine wastewater by combining partial nitrification-denitrification process with anammox

Anammox process offers reduced operational cost and energy requirement compared to nitrification-denitrification methods due to lower biomass generation and no need for external carbon sources and aeration. High ammonia concetration and low biodegradable anaerobic digester of swaine wastewater provided an advantage for the growth of anammox microorangism. An anoxic/oxic (A/O) SBR and an anammox SBR were implemented parallelly to treat the same swine wastewater with partial nitrification/denitrification and partial nitrification/anammox process, respectively, and to compare their nitrogen removal efficiency. The nitrogen removal rates (NRRs) of the A/O SBR and anammox SBR were 0.054 and 0.26 kg-N/m3/day, respectively. The lower NRR of the A/O SBR could be attributed to insufficient biodegradable organic carbon sources in the denitrification process. The kinetic parameters obtained from the two SBRs were applied to estimate the time required for using the A/O process and partial nitrification/anammox process to treat the same amount of ammonia with the same reaction volume. Results showed that the A/O process required 3.3 times the reaction time of the partial nitrification/anammox process, suggesting that the partial nitrification/anammox process is a more efficient and economic nitrogen removal process for swine wastewater treatment. The next generation sequencing results revealed that Candidatus Brocadia, ranging from 10 to 23%, was the predominant anammox bacteria in the anammox SBR. More than 78.2 % of nitrite in the anammox SBR was removed through the anammox reaction.

Optimization of Ammonia Removal from Landfill Leachate by Aeration Using Response Surface Methodology (RSM)

Landfill leachate has a high concentration of ammonia, making it a harmful pollutant for both surface and groundwater. One of the most favoured methods for removing ammonia from leachate is aeration, as it has been proven to remove a significant amount of ammonia in the most efficient and economical way. The effect of operational variables on ammonia removal efficiency by aeration was investigated in the current study by applying Response Surface Methodology (RSM) approach. Three operating parameters such as airflow rate, aeration time and lime dosage were investigated to achieve the optimization of ammonia removal. The optimal parameters for a favourable reaction of ammonia-nitrogen (NH3N) removal were found to be 6 L/min airflow, 90 minutes aeration time, and a lime dosage of 6 g/L. At these ideal conditions, Quadratic RSM predicted a maximum NH3N removal of 98.0%, which has been validated by the experiment and successfully removed 97.6%. The finding also showed that airflow rate and aeration time were more significant than lime dosage for NH3N removal. Due to increased contact time between air and liquid, regardless of the amount of lime used, increasing the aeration period ammonia removal efficiency. Considering the influential factors, determining the optimum condition for ammonia removal by aeration will explain the potential interferences that may inhibit the efficient recovery of NH3N. Hence, aeration is a promising approach for ammonia removal from landfill leachate.

Optimization of Ammonia Removal from Landfill Leachate by Aeration Using Response Surface Methodology (RSM)

Landfill leachate has a high concentration of ammonia, making it a harmful pollutant for both surface and groundwater. One of the most favoured methods for removing ammonia from leachate is aeration, as it has been proven to remove a significant amount of ammonia in the most efficient and economical way. The effect of operational variables on ammonia removal efficiency by aeration was investigated in the current study by applying Response Surface Methodology (RSM) approach. Three operating parameters such as airflow rate, aeration time and lime dosage were investigated to achieve the optimization of ammonia removal. The optimal parameters for a favourable reaction of ammonia-nitrogen (NH3N) removal were found to be 6 L/min airflow, 90 minutes aeration time, and a lime dosage of 6 g/L. At these ideal conditions, Quadratic RSM predicted a maximum NH3N removal of 98.0%, which has been validated by the experiment and successfully removed 97.6%. The finding also showed that airflow rate and aeration time were more significant than lime dosage for NH3N removal. Due to increased contact time between air and liquid, regardless of the amount of lime used, increasing the aeration period ammonia removal efficiency. Considering the influential factors, determining the optimum condition for ammonia removal by aeration will explain the potential interferences that may inhibit the efficient recovery of NH3N. Hence, aeration is a promising approach for ammonia removal from landfill leachate.

A Durable Vanadium Disulfide-Based Catalyst for Nitrate Reduction and Insights on in-Line Ammonia Detection By Mass Spectrometry

Ammonia is critical to agriculture worldwide and is a renewable fuel. The dominant process for ammonia synthesis, Haber-Bosch, is fossil-fuel dependent, energy intensive and highly centralized. Electrochemical N2 or NO3 - reduction promises to provide a decentralized and environmentally friendly route to ammonia synthesis. Electrochemical ammonia synthesis research is challenging due to typically low amounts of ammonia produced relative to environmental levels. In this two-part presentation, a VS2-based nitrate reduction catalyst, which has shown exceptional activity, selectivity, and durability, will be discussed. The proposed mechanism of nitrate reduction on VS2 will be discussed along with thorough characterization of the catalyst material, and we will present density functional theory mechanistic insight of nitrate reduction on VS2. Various experimental controls used in the VS2 nitrate reduction experiments, including Ar purge and NMR characterization experiments will also be detailed. Additionally, a test platform for nitrogen or nitrate reduction catalysts in a gas-diffusion electrode architecture with in-line NH3 and 15NH3 monitoring by multi-turn TOF-MS will be discussed. This part of the presentation will detail some advantages of our analytical approach that stem from the low limit of detection and high mass resolution. Finally, we will address areas of opportunity in electrochemical ammonia generation.

Dynamics and activity of an ammonia-oxidizing archaea bloom in South San Francisco Bay.

Transient or recurring blooms of ammonia-oxidizing archaea (AOA) have been reported in several estuarine and coastal environments, including recent observations of AOA blooms in South San Francisco Bay (SFB). Here, we measured nitrification rates, quantified AOA abundance, and analyzed both metagenomic and metatranscriptomic data to examine the dynamics and activity of nitrifying microorganisms over the course of an AOA bloom in South SFB during the autumn of 2018 and seasonally throughout 2019. Nitrification rates were correlated with AOA abundance in qPCR data and both increased several orders of magnitude between the autumn AOA bloom and spring and summer seasons. From bloom samples, we recovered an extremely abundant, high-quality Ca. Nitrosomarinus catalina-like AOA metagenome-assembled genome (MAG) that had high transcript abundance during the bloom and expressed >80% of genes in its genome. We also recovered a putative nitrite-oxidizing bacteria (NOB) MAG from within the Nitrospinaceae that was of much lower abundance and had lower transcript abundance than AOA. During the AOA bloom, we observed increased transcript abundance for nitrogen uptake and oxidative stress genes in non-nitrifier MAGs. This study confirms AOA are not only abundant, but also highly active during blooms oxidizing large amounts of ammonia to nitrite - a key intermediate in the microbial nitrogen cycle - and producing reactive compounds that may impact other members of the microbial community.

Optimization of direct-injection ammonia-diesel dual-fuel combustion under low load and higher ammonia energy ratios

Ammonia (NH3), as a potential zero-carbon fuel, has garnered significant attention for its application in compression ignition (CI) engines. Due to the low reactivity, ammonia is primarily used as dual fuel in CI engines. Therefore, the decarbonization potential is influenced by the ammonia energy ratio (AER). In this study, experimental research was conducted on expanding the AER at low load conditions in a direct-injection ammonia-diesel dual-fuel engine. The ammonia post-injection strategy was explored and significantly improved the suppression effect of high-concentration ammonia on diesel ignition, which could advance ignition timing and increase the peak heat release rate. As a result, coupled with intake heating, it expanded AER to 86 % at an indicated mean effective pressure (IMEP) of 4 bar. This strategy also increased the indicated thermal efficiency (ITE) by 8 % and significantly reduced unburned ammonia emissions. However, the combustion and emission performance was limited by the post-injection ammonia quantity and the injection timing of both diesel and ammonia, especially under high AER conditions.

Investigation of the chemical mechanism of pollutant formation in co-firing of ammonia and biomass lignin

Ammonia (NH3) and biomass are recognised as renewable energy carriers with substantial promise for reducing carbon emissions. However, the issue of nitrogen oxides (NOX, including NO and NO2) and nitrous oxide (N2O) emissions from ammonia combustion and soot from biomass combustion, remains a pressing concern due to their detrimental impacts on the environment and human health. This study investigated the mechanism of pollutant formation during ammonia-lignin co-firing through reactive molecular dynamics (RMD) simulations. The results indicate that co-firing a certain amount of ammonia with lignin can reduce the formation of soot. This is mainly due to NH2 radicals converting a portion of polycyclic aromatic hydrocarbon (PAH) precursors into C–N compounds. However, it is necessary to maintain higher ammonia concentrations. Adding a small quantity of ammonia would decrease the extent of oxidative reactions within the system and fail to generate enough NH2 radicals to consume the carbon atoms forming PAH precursors, ultimately resulting in increased soot production. The impact of lignin on the formation of NOX and N2O during ammonia combustion has two main aspects: Firstly, the oxidising radicals formed during the initial decomposition of lignin promote the generation of N–O bonds, leading to an increase in the quantities of NOX and N2O during the initial reaction stage. Secondly, the carbon-containing products produced from lignin decomposition consume nitrogen atoms by forming N–C bonds, thereby diminishing available nitrogen atoms for nitrogen oxides formation. This study provides new insights into the formation of primary pollutants of ammonia and biomass co-firing on an atomic scale, which can help develop pollutant mitigation measures.

Investigating Methane, Carbon Dioxide, Ammonia, and Hydrogen Sulphide Content in Agricultural Waste during Biogas Production

The agricultural industry produces a substantial quantity of organic waste, and finding a suitable method for disposing of this highly biodegradable solid waste is a difficult task. The utilisation of anaerobic digestion for agricultural waste is a viable technological solution for both renewable energy production (biogas) and waste treatment. The primary objective of the study was to assess the composition of biogas, namely the percentages of methane, carbon dioxide, ammonia, and hydrogen sulphide. Additionally, the study aimed to quantify the amount of biogas produced and determine the methane yield (measured in NmL/g VS) from different agricultural substrates. The biochemical methane potential (BMP) measurements were conducted in triplicate using the BPC Instruments AMPTS II instrument. The substrates utilised in the investigation were chosen based on their accessibility. The substrates used in this study comprise cattle manure, chicken manure, pig manure, tomato plants, tomatoes, cabbage, mixed fruits, mixed vegetables, dog food, and a co-digestion of mixed vegetables, fruits, and dog food (MVMFDF). Prior to the cleaning process, the makeup of the biogas was assessed using the BIOGAS 5000, a Geotech Analyser. The AMPTS II flow cell automatically monitored and recorded the volume of bio-methane produced after the cleaning stage. The data were examined using the Minitab-17 software. The co-digestion of mixed vegetables, mixed fruits, and dog food (MVMFDF) resulted in the highest methane level of 77.4%, followed by mixed fruits at 76.6%, pig manure at 72.57%, and mixed vegetables at 70.1%. The chicken manure exhibited the greatest levels of ammonia (98.0 ppm) and hydrogen sulphide (589 ppm). Chicken manure had the highest hydrogen sulphide level, followed by pig manure (540 ppm), tomato plants (485 ppm), mixed fruits (250 ppm), and MVMFDF (208 ppm). Ultimately, the makeup of biogas is greatly affected by the unique qualities of each substrate. Substrates containing elevated quantities of hydrogen sulphide, such as chicken manure, require the process of biogas scrubbing. This is because they contain substantial amounts of ammonia and hydrogen sulphide, which can cause corrosion to the equipment in biogas plants. This emphasises the crucial need to meticulously choose substrates, with a specific focus on their organic composition and their capacity to generate elevated methane levels while minimising contaminants. Substrates with a high organic content, such as agricultural waste, are optimal for maximising the production of methane. Furthermore, the implementation of biogas scrubbing procedures is essential for efficiently decreasing carbon dioxide and hydrogen sulphide levels in biogas. By considering and tackling these problems, the effectiveness of biogas generation can be enhanced and its ecological consequences alleviated. This strategy facilitates the advancement of biogas as a sustainable energy source, hence contributing to the attainment of sustainable development goals (SDGs).