Initial Ammonia Nitrogen Concentration Research Articles

Study on the purification mechanism for ammonia nitrogen in micro-polluted rivers by herbaceous plant - Rumex japonicus Houtt

Water eutrophication caused by nitrogen pollution is an urgent global issue that requires attention. The Qingyi River is a typical micro-polluted river in China. In this study, we took this river as the research object to investigate the nitrogen pollution purification capacity of a herbaceous plant, Rumex japonicus Houtt. (RJH). Compared to nitrate nitrogen (NO3−-N) and nitrite nitrogen (NO2−-N), RJH showed better purification performance on total nitrogen (TN), total phosphorus (TP) and ammonia nitrogen (NH4+-N), with a highest removal rate of 37.22%, 52.13%, and 100%, respectively. RJH could completely remove ammonia nitrogen and exhibit excellent resistance to pollutant interference when the initial concentration of ammonia nitrogen in the cultivation devices increased from 1 mg/L to 10 mg/L or in the actual river. This indicated the great application potential of RJH in ammonia nitrogen removal from natural micro-polluted rivers. In addition, combined effects of nitrification of roots, absorption of self-growth, stripping, and others contributed to nitrogen removal by RJH. Particularly, the nitrification of roots played a dominant role, accounting for 73.85% ± 8.79%. High-throughput sequencing results indicate that nitrifying bacteria accounted for over 75% of all bacterial species in RJH. Furthermore, RJH showed good growth status and strong adaptability. The correlation coefficients of its relative growth rate with chlorophyll A and the degradation rate of absorption were 0.9677 and 0.9594, respectively. Our research demonstrates that RJH is one of the excellent varieties for ammonia removal. This provides a very promising and sustainable method for purifying micro-polluted rivers.

Preparation of NaA zeolite molecular sieve based on solid waste fly ash by high-speed dispersion homogenization-assisted alkali fusion-hydrothermal method and its performance of ammonia-nitrogen adsorption

A high-speed dispersion homogenization-assisted alkali fusion-hydrothermal method was successfully developed for the preparation of NaA zeolite molecular sieve with excellent adsorption performance for ammonia nitrogen using solid waste fly ash. The zeolite molecular sieve, prepared at a calcination temperature of 700 °C and a crystallization temperature of 80 °C, was identified as NaA zeolite molecular sieve through XRD and SEM tests, exhibiting a uniform and ordered cubic crystal structure. The result of BET analysis indicates that the NaA zeolite molecular sieve has a specific surface area of 288.219 m2/g and a plentiful pore structure. The effect of pH, adsorption time, and initial concentration of ammonia nitrogen on the adsorption capacity of NaA zeolite molecular sieve was also investigated. The fitting analysis of experimental adsorption data using adsorption kinetics and isotherm models indicates that the kinetic adsorption of ammonia nitrogen solution by zeolite molecular sieve follows the second-order kinetic model more closely. The Langmuir model shows a better correlation than the Freundlich model, suggesting that the adsorption of ammonia nitrogen solution by the zeolite molecular sieve is mainly based on the surface-uniform monolayer physical adsorption process. Under the conditions of pH = 7 and an initial ammonia nitrogen concentration of 100 mg/L, the adsorption capacity of the zeolite molecular sieve for ammonia nitrogen within 60 min can reach 27.5 mg/g, showing excellent adsorption performance. This study establishes a vital research foundation for the utilization of fly ash and the treatment of ammonia nitrogen wastewater, with great ecological and social benefits.

Study on adsorption of ammonia nitrogen by sodium-modified kaolin at calcination temperature.

Natural kaolin (NK) is not used as a material for removal of ammonia nitrogen in wastewater because of its low ammonia adsorption capacity. In this study, sodium-modified kaolin adsorbent (NaCK) with high ammonia nitrogen adsorption capacity was prepared by NaOH modification of calcined NK, which was developed to address this problem. The adsorption properties were evaluated by batch static adsorption test. The results showed that when the initial concentration of ammonia nitrogen was 10 mg/L, pH = 8, and dosage of adsorbent was 1 g/L, the adsorption capacity of NaCK-600 for ammonia nitrogen was the best, reaching 6.23 mg/g, which was 34.6 times higher than that of NK (0.18 mg/g). Batch static adsorption test combined with adsorption kinetics, adsorption isothermal, and characteristic data showed that NaCK prepared at different temperatures had different adsorption mechanisms. Batch static adsorption test data of NaCK-600 was in good agreement with the pseudo-second-order model and Langmuir model, and the main mechanism of its adsorption of ammonia nitrogen was the ion exchange of NH4+ and Na+ in NaCK. After the third cycle, the removal rate of NaCK-600 was still up to 76.44%, which indicates that NaCK-600 has considerable potential for removal of ammonia nitrogen in wastewater and provides a new way for the application of kaolin in removal of ammonia nitrogen.

Adsorption of Low-Concentration Ammonia Nitrogen from Water on Alkali-Modified Coal Fly Ash: Characterization and Mechanism

The huge annual output of coal fly ash is harmful to the environment, but it is widely used because of its good adsorption potential. In this study, using coal fly ash as a raw material and sodium hydroxide as an activator, a novel adsorbent was synthesized at 300 °C and used to adsorb low concentrations of ammonia nitrogen from water. In this study, scanning electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, and a surface area and porosity analyzer were used to analyze the adsorbent’s physicochemical properties. The results showed that after alkali modification, the activity of the adsorbent had greatly enhanced. The impacts of solution pH, adsorbent dosage, adsorption time, and initial concentration of ammonia nitrogen on the adsorption capacity and removal efficiency were evaluated through a series of adsorption experiments. Moreover, the adsorption data were better fitted to the pseudo-second-order kinetic model and Langmuir model, indicating that the adsorption process was mainly chemical adsorption and monolayer uniform adsorption. As a result, the new adsorbent is inexpensive and effective, and it could be used to remove low-concentration ammonia nitrogen from water with a maximum removal efficiency of approximately 89%.

The Preparation of {001}TiO2/TiOF2 via a One-Step Hydrothermal Method and Its Degradation Mechanism of Ammonia Nitrogen.

{001}TiO2/TiOF2 photocatalytic composites with a high activity {001} crystal plane were prepared by one-step hydrothermal methods using butyl titanate as a titanium source and hydrofluoric acid as a fluorine source. X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), raman spectroscopy, N2 adsorption-desorption curve (BET), UV-Vis diffuse absorption spectroscopy (UV-Vis DRS), X-ray photoelectron spectroscopy (XPS), and fluorescence spectroscopy (PL) were used to evaluate the structure, morphology, specific surface area, optical properties, and photocarrier separation ability of {001}TiO2/TiOF2. Ammonia nitrogen was taken as the target pollutant, and the degradation performance of the catalyst was investigated. The results show that hydrofluoric acid improves the content of {001} crystal plane of TiO2 with high activity; it also improves the specific surface area and dispersion of the composite material and adjusts the ratio of {001}TiO2 to TiOF2 in the composite material to enhance the absorption capacity of the composite material and reduce the band gap width of the composite material. The degradation rate of ammonia nitrogen by 100 mg F15 is 93.19% when the initial concentration of ammonia nitrogen is 100 mg/L and pH is 10. Throughout the reaction process, the {001}TiO2/TiOF2 composite produces superoxide anion radical (·O2−) and hydroxyl radical (·OH) to oxidize NH3·H2O and generate N2 accompanied by a small amount of NO3− and NO2−.

Preparation of low-cost functionalized diatomite and its effective removal of ammonia nitrogen from wastewater.

A low-cost functionalization method was used to treat diatomite, and an efficient adsorbent for ammonia nitrogen was prepared by optimizing the functionalization conditions. The functionalized diatomite (DTCA-Na) was characterized by SEM, EDS, BET, XRD, FT-IR, and TG. The results demonstrate that DTCA-Na has excellent adsorption performance after being modified with H2SO4 (60.00 wt.%), NaCl (5.00 wt.%), and calcination at 400°C for 2h. While studying the effect of adsorption factors on the removal of ammonia nitrogen, the kinetic and thermodynamic behaviors in the adsorption process were discussed. The removal efficiency of the simulated wastewater with the initial ammonia nitrogen concentration of 10.00mg L-1 by the DTCA-Na was more than 80% when the contact time was 60min, pH was 6-10, the dosage of adsorbent was 1.00g, and the temperature was 25°C. The adsorption process of ammonia nitrogen was conformed to the pseudo-first-order and Langmuir isothermal model. The removal efficiency of ammonia nitrogen was still above 80% after 5 times adsorption-desorption experiments. The DTCA-Na has a brighter prospect of application in the field of ammonia nitrogen wastewater treatment due to its excellent adsorption performance and low-cost advantage.

Efficient Removal Technology of Ammonia Nitrogen by Membrane Separation

AbstractThe working principle, process flow, treatment effect, and application scope of ammonia nitrogen removal by membrane separation were investigated. The effects of initial ammonia nitrogen concentration, pH value, and flow rate of raw water on mass transfer coefficient and removal rate of ammonia nitrogen in the membrane separation process were evaluated, and the optimal operating conditions of membrane separation were assessed. In addition, several kinds of representative wastewaters were treated. Under the optimal operating conditions, the ammonia nitrogen removal rate can reach more than 99 % and the specific surface area can be up to 3000 m2m−3.

FLUENT Simulation Design and Optimization of Biological Aerated Filter

In this paper, a small biological aerated filter for experimental use was designed, and a method was explored to optimize the nitrogen removal efficiency by using FLUENT software to simulate the particle size of the filler, the amount of the filler, the initial concentration of ammonia nitrogen, dissolved oxygen and other operating parameters. Through the simulation experiment, the optimal design parameters of the particle size of filler, the amount of filler, the initial concentration of ammonia nitrogen and the dissolved oxygen of the biological aerated filter are 4mm, 60%, 15% and 1.5%, respectively, when the removal efficiency of ammonia nitrogen exceeds 30% reported in the literature. It provides a reference for the experimental research and practical application of biological aerated filter (BAF) denitrification.

Significant removal of ammonia nitrogen in low concentration from aqueous solution at low pH by advanced air stripping.

In recent years, the excess discharge of ammonia nitrogen from wastewater into surface water has been regulated by more stringent standard. The air stripping method is successfully used to treatment of high-concentration ammonia nitrogen; however, alkali will be added to keep pH more than 10, which is costly and not environment-friendly operation. In this study, an advanced air stripping (AAS) based on foam separation of removing ammonia nitrogen in low concentration from aqueous solution at low pH was proposed. The effect of conditions such as air flow rate, temperature, SDS dosage, coexisting ionic strength, pH, and initial ammonia nitrogen concentration on the removal efficiency was studied. The advanced air stripping exhibited favorable removal efficiency for NH4+-N in low concentration from aqueous solution (20 mg·L-1) with a broad range of low pH 3.0-9.0. Besides, for strongly alkaline (pH=11.0) solution, the advanced air stripping can alleviate the decrease of pH to some extent and keep ammonia nitrogen stripping out continuously based on equilibrium shift between NH4+ and NH3. A microcalorimeter was applied to demonstrate the interaction between the negatively charged hydrophilic groups of SDS and NH4+ ions, helping to understand the mechanisms more clearly. The simple operation and the satisfactory removal efficiency could imply that the advanced air stripping is a promising technology for minimizing low-concentration NH4+-N.

Simultaneous nitrogen removal and methane production from Taihu blue algae against ammonia inhibition using integrated bioelectrochemical system (BES).

Simultaneous nitrogen removal and methane production using an integrated bioelectrochemical system (BES) during the anaerobic digestion (AD) process of Taihu blue algae were investigated. Upon an applied voltage of 0.4V and total solids (TS) ratio of blue algae to anaerobic sludge as 1:1, the highest methanogenesis potential as 69.12mL/g VS could be obtained, attaining 18.7 times of the TS ratio group of 3:1. Moreover, methane production of the integrated BES group reached 3.18 times of the AD group using conical flask, even with the same TS ratio (1:1) and initial ammonia nitrogen concentration (1000mg NH4+-N/L). Apart from the bettered electrochemical performance, bio-augmented microbial genus responsible for acetoclastic methanogenesis, power generation, resisting to hostile circumstance, co-existence with hydrogenotrophic methanogens could all be enriched. Therefore, integrated BES with appropriate TS ratio under applied voltage might help offset both the ammonia and electrical stress, thereby to maintain enhanced biomethanation performance.

Removal of ammonia nitrogen in aquaculture wastewater by composite photocatalyst TiO2/carbon fibre

AbstractIn this study, TiO2/Carbon fibre (CF) composite photocatalyst was prepared by sol‐gel method, and its characterization was analysed by SEM and XRD. Under the ultraviolet light, the effects of various single factors on the removal of ammonia nitrogen from aquaculture wastewater by TiO2/CF were discussed. Orthogonal experiments were performed to determine the most beneficial conditions for ammonia nitrogen removal. When the dosage of TiO2/CF was 2.0 g/L, the initial concentration of ammonia nitrogen was 30 mg/L, the calcination temperature was 600°C, the concentration of H2O2was 0.8 g/L, the illumination time was 1 hr, TiO2/CF had excellent performance of remove ammonia nitrogen. The results show that compared with the treatment of ammonia nitrogen by CF or TiO2, TiO2/CF was more effective in the removal of ammonia nitrogen. TiO2/CF composite material was applied to the treatment of ammonia nitrogen in marine aquaculture wastewater for the first time, which provides a scientific and effective treatment method for photocatalytic technology in later industrial treatment process.

Effect of superficial gas velocity and ratio of bed volume to reactor volume of inverse fluidized bed biofilm reactor on the removal of ammonia-nitrogen from wastewater

Hydrodynamic parameters of an inverse fluidized bed biofilm reactor (IFBBR) have been studied using spherical polypropylene (PP) particles having average diameter and density of 5.63 mm and 920 kg/m3 respectively. Gas-phase holdup (g) was analyzed for various ratios of settled bed volume to reactor volume (Vb/Vr) and superficial gas velocities (Ug) with a liquid recirculation velocity (Ul) of 0.0021 m/s. The g values were found to increase with Vb/Vr ratios up to a certain limit and then decrease with further increase of Vb/Vr ratios. The effect of Ug, Vb/Vr ratios, and initial concentration of ammonia-nitrogen (NH4 +-N) on the removal of NH4 +-N from synthetic wastewater were studied. The optimal values of Vb/Vr ratio and Ug were found to be 0.380 and 0.0085 m/s respectively for all initial NH4 +-N concentrations. Complete removal of NH4 +-N was achieved in 8 to 44 hours for different initial NH4 +-N concentrations. It was also observed that with the increase in initial NH4 +-N concentrations, the nitrification decreases.

Preparation of Hollow SiO₂@BiOI Nanocomposites and Their Photocatalytic Performance in Ammonia Nitrogen Degradation.

Hollow SiO₂ microsphere-supported bismuth oxyiodide (BiOI) nanocomposites were prepared using Bi(NO₃)₃ · 5H₂O and KI as the precursors of BiOI at 80 °C in an aqueous solution by the liquid chemical deposition method. The BiOI nanosheets with the thicknesses of 25-40 nm and the widths of 1-2 μm were deposited on the hollow SiO₂ microsphere surfaces. There were interactions between the BiOI nanosheets and hollow SiO₂ microspheres, which enlarged the ban gap of the BiOI nanosheet as compared with the pure BiOI. The band gap energy increased with the increase in SiO₂/BiOI weight ratios. The hollow SiO₂@BiOI nanocomposites showed high photocatalytic activity in ammonia nitrogen degradation when the photocatalytic degradation reaction was performed in aqueous solution under visible light irradiation. The degradation extent of ammonia nitrogen was upto 81% when the ammonia nitrogen degradation reaction was photocatalyzed by the hollow SiO₂@BiOI(100:10) nanocomposite at an initial concentration of ammonia nitrogen of 10 mg L-1 and 25 °C for 4 h. The reaction kinetics of ammonia nitrogen degradation was well simulated by the first-order reaction model.

Non-thermal plasma combined with zeolites to remove ammonia nitrogen from wastewater

In this work, non-thermal plasma combined with zeolites was used to remove inorganic pollutant ammonia nitrogen from wastewater. Ammonia nitrogen elimination performances at various operating parameters were investigated. Roles of active species in the removal of ammonia nitrogen were also discussed. The experimental results showed that 69.97% ammonia nitrogen can be removed from the plasma/zeolites synergistic system after 30 min treatment. The removal efficiency was 16.23% and 61.55% higher than that in sole zeolites adsorption system and that in sole discharge plasma system, respectively. Higher applied voltage, lower initial ammonia nitrogen concentration and weak acidic conditions were favorable for ammonia nitrogen removal. After the addition of zeolites, part of O3 and H2O2 generated in the plasma/zeolites system were decomposed into other oxygen species (•OH and 1O2), which improved the oxidation degree of ammonia nitrogen. In addition, the reaction mechanism of ammonia nitrogen in water by plasma/zeolites process was discussed. After repeated use three times, the effect of the zeolites in the plasma/zeolites system remained stable. Characterization of the zeolites after reaction was analyzed through BET, SEM, XRD and FT-IR. The experiments have confirmed the applicability of the plasma/zeolites system for the further treatment of low-concentration ammonia nitrogen wastewater.

Effectiveness of Scenedesmus sp. Biomass Grow and Nutrients Removal from Liquid Phase of Digestates

One of the most important factors in determining the profitable production of microalgae biomass is the use of a cost effective growth medium that is rich in nutrients. The objective of the study was to determine the possibility of using digestates from anaerobic digestion of different feedstock mixtures as the media for Scenedesmus sp. cultivation. A different liquid digestate composition was obtained in terms of organic compounds, phosphorus, and nitrogen concentrations, depending on the substrates used in the anaerobic digestion. It was found that the highest biomass production was obtained when using digestate from anaerobic digestion of the feedstock mainly composed of microalgae biomass, which was characterized by low organic compounds concentration. In this case, the average biomass concentration reached 2382 mg total solids/L. A lower Scenedesmus sp. biomass yield was obtained using digestate from anaerobic digester processing feedstock based on maize silage and cattle menure. In the variants of the study, it was also found that the increase in the initial concentration of ammonia nitrogen in the growth medium up to 160 mg/L significantly reduced the growth of Scenedesmus sp. The results indicated the possibility of a high ammonia nitrogen and orthophosphates removal from anaerobic digestates by Scenedesmus sp. microalgae. Phosphorus concentration in the cultivation medium is a limiting factor for the growth of Scenedesmus sp., thus phosphorus supplementation should be considered when using liquid digestate as the culture medium. The optimization model indicated that the volume of liquid digestate that was used for preparing the cultivation medium, the initial concentration of organic compounds, and the initial concentration of ammonia nitrogen had a significant impact on the production of Scenedesmus sp. biomass.

Synthesis of Two Kinds of Mesoporous Diatomite by Microwave Assisted Sol-Gel Method and Its Adsorption of Ammonia Nitrogen in Wastewater

The microwave-assisted sol-gel method was used to synthesize mesoporous diatoms (DM) and magnetic mesoporous diatoms (MDM), and used as adsorbent to remove ammonia nitrogen from water. The effect of reaction time, solution pH, and initial concentration of ammonia nitrogen on adsorption was studied, and the adsorption Kinetics and thermodynamic characteristics of DM and MDM were analyzed. The results showed that at 25 °C, when the dosage of DM and MDM was 4 g/L, the initial concentration of ammonia nitrogen in the solution was 50 mg/L, the value of pH was 7, and the adsorption time was 30 min, the adsorption of ammonia nitrogen in solution by DM and MDM was 6.95 and 7.79 mg/g, respectively. DM and MDM had good adsorption effect on ammonia nitrogen, and the adsorption process complied with the Pseudo-second-order kinetics equation and Freundlich isothermal adsorption model.

Dielectric barrier discharge-coupled Fe-based zeolite to remove ammonia nitrogen and phenol pollutants from water

In this work, dielectric barrier discharge (DBD) coupled with Fe-based zeolite catalyst was used to treat ammonia nitrogen and phenol wastewater. This experiment mainly investigated the effects of discharge voltage, discharge frequency, zeolite dosage, initial solution concentration and pH on ammonia nitrogen or phenol removal. Results showed that the removal rate of ammonia nitrogen increased with increased discharge voltage, discharge frequency, zeolite dosage, and initial pH and decreased with increased initial ammonia nitrogen concentration. The best removal rate of ammonia nitrogen reached 75.11%, which was higher than removal rates of the solutions treated with zeolite adsorption alone (10.93%) and DBD discharge alone (9.67%). However, the removal rate of phenol increased with discharge voltage, discharge frequency, and zeolite dosage and decreased with increased initial phenol concentration and initial solution pH. After 20 min of reaction, the removal rate of phenol reached 56.67%, which was higher than the removal rates of the solutions treated with zeolite adsorption alone (20.61%) and DBD discharge alone (3.54%).Therefore, a DBD-coupled metal zeolite catalyst system has a good treatment effect on inorganic and organic wastewater. In addition, DBD-coupled Fe-based zeolite catalyst was used to simultaneously treat mixed ammonia nitrogen and phenol wastewater. The degradation process and mechanism of mixed ammonia nitrogen and phenol wastewater in the system were studied to reflect the synergistic effect of the system.

Adsorption of Ammonia Nitrogen in Aqueous Solution Using Zeolite A

The capacity of alternative adsorbents including rice straw, delignified rice straw and zeolite A for ammonia nitrogen removal from aqueous solution was investigated. The adsorption experiments were carried out in batch system with initial ammonia nitrogen concentration of 0.5 mg-N/l, 1000 ml ammonia nitrogen solution for 1 g of adsorbent. Experimental data indicated that rice straw and delignified rice straw cannot adsorb ammonia nitrogen. However, zeolite A provided rapidly adsorption capacity for ammonia nitrogen removal. The amount of ammonia nitrogen adsorbed by zeolite A was 0.256 mg/g at 1 minute after the experiment was initially conducted and slightly stable at 0.275 mg/g after 10 minutes. The adsorption experiments were carried out at 0.25, 0.5, 1.0, 2.0, 4.0, and 8.0 mg-N/l of ammonia nitrogen concentration. The results indicated that zeolite A had the adsorption capacity of 0.102, 0.294, 0.551, 1.153, 2.303, and 3.897 mg/g respectively at equilibrium time. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. Based on R2, Freundlich model was more promising to represent the adsorption data than Langmuir model.

Modified carbon nitride as an efficient adsorbent for ammonia nitrogen with low concentration

AbstractThe adverse effects of excessive ammonia on aquatic ecosystem have provoked the development of efficient methods for its removal. Here, we present a thermal copolymerization of melamine and sodium hydrogen carbonate and successfully introduce oxygen groups into the structure of g‐C3N4, which is applied to low‐concentration ammonia removal. Oxygen groups are introduced into g‐C3N4 and increase its surface electron negativity. When the initial concentration of ammonia nitrogen is 18.74 mg L−1, the lowest concentration of it after adsorption is 1.43 mg L−1, and the ammonia nitrogen removal efficiency is 92.3%. The main reason for our material high performance on adsorption ammonium may be ascribed to deprotonated carboxylic acid, which has the ability to adsorb positively charged ammonium ions.

Adsorption Properties of Ammonia Nitrogen in Aqueous Solution by Various Materials

Focusing on the removal of ammonia nitrogen from polluted water, the absorption properties of five materials (zeolite, maifanite, diatomite, bentonite, and activated carbon) were tested. Results showed that the pseudo-second-order kinetic equation was suitable for data fitting for the five materials. The maximum theoretical adsorption capacities of the five materials were 2.0673 mg·g-1, 0.9982 mg·g-1, 0.7580 mg·g-1, 1.7486 mg·g-1, and 1.0160 mg·g-1, respectively, which were close to the experimental value. Chemical-based adsorption was the main mode of adsorption. Data for diatomite were fitted using the Langmuir isotherm equation, and belonged to the single-layer molecular adsorption group, while the other four materials were fitted using the Freundlich isotherm equation, belonging to the multi-layer molecular adsorption group. Moreover, the results showed that the removal rates of ammonia nitrogen by zeolite, diatomite, bentonite, and activated carbon increased with an increase in dosage, and the maximum removal rates were 100%, 10.46%, 49.25%, and 16.87%, respectively. A maifanite dosage of 0.4g achieved the maximum removal rate of 48.85%. At pH 4-10, the adsorption capacities of zeolite and maifanite first increased and then decreased, while that of diatomite, bentonite, and activated carbon slowly increased. The desorption capacity of the five tested materials increased with an increase in the initial concentration of ammonia nitrogen.