Initial Ammonia Concentration Research Articles

The investigation into the ammonium removal performance of Yemeni natural zeolite: Modification, ion exchange mechanism, and thermodynamics

This paper present the first attempt to investigate the potential use of Yemeni (Al-Ahyuq) natural zeolite on the effectiveness of ammonium ion (NH4+) removal. The kinetics and isotherms of ion exchange were studied in a batch system. Important parameters which affect the ion exchange, such as optimal modified zeolite (SNZ), pH of solution, temperature, contact time, zeolite mass and initial ammonium concentration were investigated. The characteristics of modified zeolite (SNZ) and its mechanism of ammonium removal was investigated and compared with that of natural zeolite (NZ). Both zeolites were fully characterized by scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) technique, zeta potential (Z-potential), X-ray diffraction (XRD), X-Ray Fluorescence (XRF),Fourier transform infrared spectroscopy (FTIR), thermogravimetry analyzes (TGA) and specific surface area (SSA) analysis. The results demonstrate that the SNZ has a high selectivity for NH4+ and had maximum removal efficiency reaching up to 99% based on relevant parameters. The highest ion exchange capacity was obtained at 35°C and pH of 8. Moreover, the kinetic data followed more closely the pseudo-second order model whereas ion exchange isotherm was suitably described by the Langmuir model (LM). In addition to that, Kielland plots and thermodynamic parameters such as change in free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were also calculated. The parameters revealed that the exchange process of ammonium ion by zeolite is spontaneous and exothermic. The results indicate that the modified Yemeni zeolite has significant potential as an economic and effective adsorbent material for ammonium removal from aqueous solutions.

Role of nitrification in the biodegradation of selected artificial sweetening agents in biological wastewater treatment process

The biodegradation of the six artificial sweetening agents including acesulfame (ACE), aspartame (ASP), cyclamate (CYC), neohesperidindihydrochalcone (NHDC), saccharin (SAC), and sucralose (SUC) by nitrifying activated sludge was first examined. Experimental results showed that ASP and NHDC were the most easily degradable compounds even in the control tests. CYC and SAC were efficiently biodegraded by the nitrifying activated sludge, whereas ACE and SUC were poorly removed. However, the biodegradation efficiencies of the ASs were increased with the increase in initial ammonium concentrations in the bioreactors. The association between nitrification and co-metabolic degradation was investigated and a linear relationship between nitrification rate and co-metabolic biodegradation rate was observed for the target artificial sweeteners (ASs). The contribution of heterotrophic microorganisms and autotrophic ammonia oxidizers in biodegradation of the ASs was elucidated, of which autotrophic ammonia oxidizers played an important role in the biodegradation of the ASs, particularly with regards to ACE and SUC.

A new application of giant reed waste material for ammonium removal

Excess nitrogen is one of the main causes of eutrophication in water bodies. In this study, the undesirable agricultural lignocellulosic material giant reed was used to remove ammonium ions from aqueous solutions. Batch experiments were conducted to investigate the effect of various parameters such as contact time, initial ammonium concentration, adsorbent dosage, pH, particle size, agitation rate and phosphate coexisting during the ammonium adsorption process. The ammonium sorption capacity of fibrous giant reed (FGR) at equilibrium was 12.49 mg N/g with a maximum removal efficiency of 76% observed within 30 min at pH range of 6.5–9.5. Results revealed that the Freundlich isotherm model fitted better with the sorption process than the Langmuir model, and the adsorption process was well described by pseudo-second-order kinetic model. FT-IR analyses indicated that complexation and ion exchange could be the main mechanisms for the ammonium removal by FGR. Results revealed that FGR has a sorption capacity comparable to that of other natural sorbents with the advantage of greater availability with no cost.

Mitigation of nitrification inhibition by silver nanoparticles using cell entrapment technique

Effects of silver nanoparticles (AgNPs) on nitrification activities of free and entrapped nitrifying activated sludge (NAS) were investigated using a respirometric assay. Initial concentrations of ammonia and AgNPs, and entrapment materials and matrix sizes were the variables. Scanning and transmission electron microscopic analyses of the microbial cells and entrapment matrices were also performed. Results showed that AgNPs (0.05–5.00 mg/L) decreased nitrification activity down to only 2 % compared to the control (free NAS without AgNP exposure). Calcium alginate and polyvinyl alcohol-entrapped cells could mitigate inhibition of nitrification activity up to 100 % (no inhibition observed) and 88 % compared to the controls (entrapped NAS without AgNP exposure), respectively. Cells entrapped in a larger matrix size (both with and without AgNP exposure) performed nitrification better. Silver nanoparticles caused damages to cell membrane and cytoplasm, which likely led to a decrease of nitrification activity. The entrapment matrices successfully reduced the adverse effects of AgNPs on nitrification activity.

N2O emission from a sequencing batch reactor for biological N and P removal from wastewater

Nitrous oxide (N2O) is a greenhouse gas that can be released during biological nitrogen removal from wastewater. N2O emission from a sequencing batch reactor (SBR) for biological nitrogen and phosphorus removal from wastewater was investigated, and the aims were to examine which process, nitrification or denitrification, would contribute more to N2O emission and to study the effects of heterotrophic activities on N2O emission during nitrification. The results showed that N2O emission was mainly attributed to nitrification rather than to denitrification. N2O emission during denitrification mainly occurred with stored organic carbon as the electron donor. During nitrification, N2O emission was increased with increasing initial ammonium or nitrite concentrations. The ratio of N2O emission to the removed ammonium nitrogen (N2ON/NH4-N) was 2.5% in the SBR system with high heterotrophic activities, while this ratio was in the range from 0.14% to 1.06% in batch nitrification experiments with limited heterotrophic activities.

Intensification of Ammonia Removal from Drinking Water with a Modified Zeolite Biological Filter Reactor

A novel modified zeolite bio-filter reactor was used for ammonia removal from drinking water, and inoculated nitrobacteria was combined with modified zeolite in this bio-filter reactor. The effects of various operation factors on the performance of the modified zeolite bio-filter reactor were investigated. The optimum operation conditions of the modified zeolite bio-filter reactor were obtained as follows: a HLR of 0.9 m3/ (m2.h), the temperature ranged from 15°C to 30°C, and no-aeration. Under these optimal conditions, the outlet concentration of ammonia was less than 0.5 mg/L, even when an initial ammonia concentration of 6 mg/L.

Impacts of temperature and nitrifying community on nitrification kinetics in a moving-bed biofilm reactor treating polluted raw water

Although nitrification kinetics have been widely studied in wastewater treatment systems to optimize the design and operation of the nitrification process, more information is still needed to fully understand the kinetics of moving-bed biofilm reactors (MBBRs) used for biological pretreatment of low ammonia concentration polluted raw water. In this study, nitrification kinetics of a pilot-scale MBBR treating polluted raw water were studied while focusing on the impacts of temperature and the nitrifying community. Nitrification batch tests were conducted with an initial ammonia concentration of 2.0mgL−1 and varying raw water temperatures of 2.8–28.3°C. The oxidation rates of ammonia and nitrite increased with temperature, although the biomass concentrations decreased from 348.7 to 188.9mgVSL−1 as temperature increased from 16.1 to 28.3°C. The specific ammonia and nitrite oxidation rates were also highly dependent on temperature. Because of severe inhibition at temperatures below 5.0°C, the temperature impacts were calibrated by eliminating the kinetic data measured below 5.0°C. Moreover, the variations in functional microorganisms for AOB (β-Proteobacterial AOB) and NOB (Nitrobacter spp.) were normalized for the modified nitrification kinetics. Thus, the final temperature coefficients were 1.099 and 1.098 for ammonia and nitrite oxidation kinetics, respectively, demonstrating the temperature impacts on nitrification kinetics in MBBRs treating polluted raw water.

Experimental study of ammonia removal from water by modified direct contact membrane distillation

In this work, a modified direct contact membrane distillation (MDCMD) with receiving solution in permeate was developed for accelerating ammonia removal from aqueous solution. The ammonia removal efficiency by means of DCMD, hollow fiber membrane contactor (HFMC) and MDCMD was comparatively investigated. And the effect of feed pH, temperature, flow rate and concentration on ammonia removal efficiency and the permeate flux in MDCMD process was studied. Experimental results showed that the ammonia removal efficiency of DCMD, HMC and MDCMD was 52%, 88% and 99.5% within 105min, respectively. In MDCMD, feed pH value was proved to be the most dominant factor and the optimal feed pH was 12.20. Increasing feed temperature and flow rate led to higher ammonia mass transfer coefficient, ammonia removal efficiency and permeate flux within the range studied. The initial ammonia concentration had a negligible effect on ammonia removal efficiency.

Isolation, Identification and Characterization of Heterotrophic Nitrifying Bacteria from Surface Water

For reducing ammonium concentration and guaranteeing safe drinking water, three heterotrophic bacteria were isolated from the Songhua River, which were SFA6, SFA7 and SFA11. When the initial ammonium concentration was about 130 mg/L, the ammonium removal rate of the strains SFA7, SFA6 and SFA 11 were 1.54 mg NH4+/L/h, 1.20 mg NH4+/L/h and 1.27 mg NH4+/L/h respectively at 8 °C. The 16S rDNA sequence results revealed that the strain SFA6 wasBacillus subtilis, SFA7 wasPseudomonas putida, and SFA11 showed similarity toPseudomonas nitroreducens. The biochemical characteristics of SFA6 were quite different from that of SFA7 and SFA11. After 48 h degradation, the NH4+-N (about 5 mg/L) was consumed to 0.23±0.15 mg/L, 0.37±0.20 mg/Land 0.58±0.17 mg/L by the strains SFA6, SFA7 and SFA11, with little NO3--N and NO2--N accumulation. Above all, the strains SFA6, SFA7 and SFA11 could be used in drinking water treatment at 8 °C. The strain SFA6 showed the highest ammonium removal efficiency.

Ammonium nitrogen removal from wastewater with a three-dimensional electrochemical oxidation system

Ammonium-containing wastewater could cause the promotion of eutrophication and a hindrance to the disinfection of water supplies. In this study, the feasibility of removing low-concentration ammonium nitrogen from synthetic and real wastewater by electrochemical oxidation was investigated. Using laboratory-scale electrochemical systems, the effects of chloride concentration, current density, anode materials, cathode materials, electrode gap, initial ammonium concentration and three-dimensional particles on the removal of ammonium nitrogen and current efficiency (CE) were evaluated. Ammonium nitrogen removal was mainly dependent upon anode materials and current density. The performance of two- and three-dimensional electrochemical oxidation systems was comparatively discussed. Both particle electrodes could enhance ammonium nitrogen removal and increase CE. However, the mechanism of the process seemed to be different. Moreover, the interaction of zeolites adsorption and electrochemical oxidation on the anode in a three-dimensional system could favor the regeneration of zeolites. Surface morphology of the used Ru-Ir-Sn/Ti anode revealed its longer working life of electrocatalysis. The result of ammonium degradation for a real wastewater treatment plant effluent showed the degradation rates in a three-dimensional system increased by 1.4 times those in a two-dimensional system.

An investigation into the adsorption removal of ammonium by salt activated Chinese (Hulaodu) natural zeolite: Kinetics, isotherms, and thermodynamics

The development of the process of sodium activation of zeolite has been an effective technique for enhancing the efficiency of ammonium removal. In this research, the optimum conditions for the activation of Chinese (Hulaodu) zeolite of the most effective parameters such as sodium concentration, stirring time, and temperature were determined. The most efficient conditions were selected according to the highest ammonium removal capacity. The characteristics of activated zeolite (ActZ) and its mechanism of ammonium removal were investigated and compared with that of natural zeolite (NZ). Additionally, both zeolites were analyzed by scanning electron microscopy (SEM), Zeta potential, X-ray diffraction (XRD), thermogravimetry (TG) and BET surface analysis. The activated zeolite revealed the highest ammonium removal efficiency reaching up to 98% based on stirring time, zeolite loading, initial ammonium concentration, temperature and pH. The adsorption kinetic was explored and fitted best with the pseudo-second-order model, whereas adsorption isotherm results illustrated that Langmuir model (LM) provided the best fit for the equilibrium data. Moreover, thermodynamic parameters such as change in free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were also calculated. The parameters revealed that the exchange of ammonium ion by activated zeolite occurred spontaneously at ambient conditions (25°C). It was concluded that when Chinese (Hulaodu) zeolite is activated under the condition of 1M NaCl, 70°C and stirring time of 30min, an excellent removal of NH4+ was obtained.

Electrolytic removal of ammonia from aqueous phase by Pt/Ti anode

This study investigated the mechanism and kinetic modeling of electrolytic degradation of ammonia with Pt/Ti anode. The results show that ammonia oxidation from direct oxidation or indirect oxidation with hydroxyl radicals was slow but can be observed under pH 9 and high initial ammonia concentration of 1,050 mg N L(-1). Indirect oxidation with HOCl was the mechanism for the chloride-mediated electrolytic removal of ammonia. In this process, pH between 3 and 9 had little effect on the ammonia removal rate, but current density (j) and chloride concentration ([Cl(-)]) showed a linear relationship with ammonia removal rate within the range of 3.8-15.4 mA cm(-2) and 30-300 mg L(-1), respectively. The ammonia removal could be described by a pseudo-zero order kinetics with a mathematic equation of k = 0.0003 × [Cl(-)] × j - 0.076. Treatment of the actual wastewater effluent from a secondary clarifier in a local wastewater treatment plant showed an ammonia removal rate of 0.8 mg N L(-1) h(-1) and energy cost of 14 kJ per mg N ammonia.

Using Microwave Energy for the Removal of Ammonia From Municipal Wastewater: Continuous Flow Lab-Scale System

This work was initiated to investigate the possibility of using a continuous flow Micro Wave (MW) radiation system with heat exchanging for ammonia nitrogen removal from municipal wastewater after the success of using the system as a batch reactor in our previous work. The effects of initial ammonia concentration, detention time, and initial temperature were investigated. The optimum detention time and initial temperature were determined using synthetic wastewater and found to be 8.5 minutes and 62 ºC, respectively. These optimum conditions are valid within the range of 60 to 120 mg NH3-N/L. The residual concentrations under optimum conditions were 3.5 ± 0.4, 4.4 ± 0.4, 5.1 ± 0.2, and 6.9 ± 0.5 mg NH3-N/L for initial concentrations of 60, 70, 80, 100, and 120 mg NH3-N/L, respectively. These concentrations meet the 5 mg NH3-N/L standard for recharging wastewater to groundwater in many countries such as Jordan .Similar results were obtained using real wastewater samples (3.1 ± 0.2, 4.0 ± 0.1 and 4.9 ± 0.3 mg NH3-N/L for initial concentrations of 65.7, 73.8, and 94.6 mg NH3-N/L, respectively). The developed system proved to be practical in the continuous flow mode that mimics the actual operations in wastewater treatment plants. It was concluded that MW energy could be one of the most effective methods for large scale removal of ammonia nitrogen from municipal wastewater.

Removal of ammonia by clinoptilolite

The important advantage of zeolite applied to water treatment is its high porosity when comparing to other minerals. The porosity results in good hydrodynamic properties (the increase in the pressure loss on the zeolite filters is 1.5-2.0 times smaller than in the case of sand filters) and adsorption roperties, and in turn high capacity which allows for adsorption of contaminants (a clinoptilolite filter allows for removal of phytoplankton and bacteria). The increase in the application of artificial fertilizers and gradual contamination of water resulted from discharging industrial wastewater into the environment led to the contamination of the environment by nitric compounds. Wastewater contains about 15-50 mg dm-3 of nitric compounds (based on nitrogen) – ammonia salts constitute about 55-60% whereas organic forms of proteins, pesticides and aminoacids about 40-50%. Natural clinoptilolite could be applied to remove ammonium ions from water and wastewater. The ammonium ion uptake behaviour of clinoptilolite is connected to the processes of ion exchange. The main aim of this investigation is to evaluate the adsorption capacity of clinoptilolite towards ammonium ions. According to the obtained results the adsorption capacity of clinoptilolite for the removal of ammonium ions demonstrates its potential application in the treatment of water, wastewater and sanitary landfill leachate contaminated with ammonia. The highest adsorption capacity of clinoptilolite towards ammonium ions of 3.79 mg g-1 was found for the initial concentration of 300 mg L-1. The highest removal level reached by clinoptilolite for ammonium was of 99.74% for the initial concentration of ammonia of 50 mg L-1. The effect of exposure time on maximum uptake of ammonia was found to be insignificant.

Thermodynamic and kinetic study on ammonium removal from a synthetic water solution using ion exchange resin

Ammonium removal from the wastewater treatment effluents is mandatory considering the imposed discharge limits and the recycling/reuse requirements. Ion exchange represents a viable alternative for the biological processes of ammonium removal, although concurrent processes make modeling complex. This study reports on the performance of a commercial cation exchange resin, PUROLITE C150H, for ammonium removal from synthetic aqueous solutions. Thermodynamic and kinetic process parameters are calculated using the Langmuir model (thermodynamic study) and the shrinking core model (kinetic study); the data are correlated with the surface properties of the substrate, outlining the adsorption mechanism. For initial ammonium concentrations of 25–150 mg NH4 +/L, removal efficiencies of 80–90 % were obtained.

Partial nitritation for subsequent Anammox to treat high-ammonium leachate

Nitrogen removal via autotrophic denitrification, an anaerobic ammonium oxidation (Anammox) process, requires an appropriate NO2-N/NH4-N ratio to provide nitrite as an intermediate. In this study, a laboratory-scale Hybrid Sequencing Batch Reactor (HSBR) was implemented for treating high-ammonium raw leachate to yield an appropriate NO2-N/NH4-N mixture as a pretreatment for subsequent Anammox. The optimal operating conditions were examined through the long-term operation of the HSBR. The experimental results showed that the prerequisite ratio of NO2-N/NH4-N was found with an initial ammonium concentration of 1200 mg/L, dissolved oxygen (DO) of 0.5–1.0 mg/L, sludge retention time (SRT) of 3 days and temperature of 31°C, which is essential for the subsequent Anammox process. Moreover, the inhibition of free ammonia (FA) and free nitrous acid (FNA) were also examined under a constant pH condition, and it was found that AOB (ammonium oxidation bacteria) had a great ability to adapt to a broad FA and FNA concentration, whereas NOB (nitrite-oxidizing bacteria) were inhibited by either FA or FNA concentration to a certain extent. It appears that partial nitritation could be implemented by facilitating FA and/or suppressing FNA concentration.

Removal of ammonium ion from aqueous solutions using natural zeolite: kinetic, equilibrium and thermodynamic studies

The aim of the present study is to investigate the removal of ammonium ions from aqueous solutions using the natural Western Azerbaijan zeolite by utilizing ion exchange process. Batch experimental studies were conducted to evaluate by changing relevant parameters such as pH, dosage of adsorbent, stirring time, initial ammonium concentration, and temperature. The results clearly confirmed that all mentioned parameters have vital affects on removing ammonium ions from wastewater and effluents, so got optimized. Adsorption kinetics and equilibrium data for the removal of ammonium ion were analyzed using Langmuir and Freundlich equations. The Langmuir model fits the equilibrium data better than the Freundlich model. According to the Langmuir equation, the maximum uptake for ammonium ion was 43.47 (mg g−1). Pseudo-first-order and pseudo-second-order models were used to represent the kinetics of the process. Kinetic studies showed that the adsorption followed a pseudo-second-order reaction. The calculated thermodynamic parameters (ΔG°, ΔH°, and ΔS°) indicate that the adsorption process is feasible, spontaneous, and endothermic at 20–50 °C. Based on the experimental results, it can be suggested that the natural Western Azerbaijan zeolite has the potential of application as an efficient adsorbent for the removal of ammonium ions from aqueous solutions, and is suggested for wastewater treatment purposes.

Influence of oxygen addition on photocatalytic oxidation of aqueous ammonia over platinum-loaded TiO2

The oxidation of aqueous ammonia over a platinum-loaded TiO2 photocatalyst was investigated for purification of wastewater. The reaction rate for the decomposition of aqueous ammonia was significantly increased by the addition of oxygen to the reaction system. The enhancement of charge separation efficiency due to consumption of photogenerated electrons by oxygen increased the decomposition rate. For dissolved oxygen (DO) concentrations below 0.09mM, the initial decomposition rate and the selectivity for nitrite and nitrate increased as DO concentration increased. Although the selectivity for nitrite and nitrate was over 90% for the initial concentration of ammonia ([NH3]i)=5.0mM under an air flow, the selectivity was suppressed as the initial concentration of ammonia was increased, e.g., 43% for [NH3]i=100mM.

Ammonia Decomposition Using Electron Beam

This study was carried out to determine the decomposition characteristics of ammonia using an electron beam (EB). Factors influencing these decomposition characteristics such as background gases (air, N2, O2, and He), initial ammonia concentration (50–150 ppm), relative humidity (0 or 90 %), and absorbed dose (1–15 kGy) were investigated. In the results of removal characteristics by different background gases, the decomposition efficiency of ammonia was lower (approximately 45 % at 5 kGy) when He was used as a background gas compared to the efficiencies when other background gases were selected. Ammonia removal efficiencies, when initial concentrations were 50 and 150 ppm, were 95 and 75 %, respectively, at 15 kGy. Ozone generation by EB irradiation increased from 2.5 kGy and reached a maximum of 45 ppm when 5 kGy of the absorbed dose was irradiated. However, ozone generation started to decrease when the absorbed dose exceeded 5 kGy and decreased to 0.27 ppm at 15 kGy.

Study on Treatment of Ammonia Nitrogen Waste Water by Zeolite-Granule-Adsorbent

This paper focuses on the zeolite-granule-adsorbent(ZGA)’s efficiency of removing ammonium ion. The ZGA shows good performance with up to 73.41% for ammonium removal on the condition of ZGA loading 6g, contact time 6h, initial ammonium concentration 50 mg/L and pH=6. The adsorption kinetics is best approximated by the pseudo-second-order model, whereas the adsorption isotherm results indicated that Langmuir model provides the best fit for the equilibrium data. Furthermore, with regard to thermodynamic parameters, it was found that Gibbs free energy change (ΔG°) −19.31kJ/mol at T=298K, The negative data indicates the spontaneous nature of the adsorption process.