Papers by Keyword: Ammonium Nitrogen

Abstract: The process of adsorption treatment of effluents from ammonium ions is considered as an integrated two-stage process consisting of the stage of adsorption of contaminants by natural sorbents in the apparatus with a stirrer and the liquid separation stage and solid phases. Mathematical models of ammonium ions adsorption from effluents by natural dispersed sorbents are proposed, based on the assumption that the process is described by Langmuir and Friendlich isotherms. The values of ion exchange equilibrium constants for different types of natural sorbents have been established by identifying experimental data for theoretical dependences. The obtained constants can be used to calculate the average concentration of ammonium ions in the solution and in the grain of the sorbent in the process of integrated adsorption process. Based on the analysis of the research results, the optimum method of the spent sorbent separation was selected - separation of the suspension of purified ammonium-containing effluents - spent sorbent under the action of gravity. Indicators of optimization of complex process of sewage treatment from ammonium ions are offered.

Abstract: Natural zeolites are materials which, due to the peculiarities of their crystal structure and high adsorption and ion exchange properties, have wide prospects for use in technologies of adsorption purification of aquatic environments. The paper presents the results of laboratory research in dynamic and static conditions of sorption properties of natural zeolite, which is currently used for purification of natural water from suspended solids in industrial water treatment plants. The sorption capacity of different fractions of this zeolite to ammonium nitrogen, fluorides and petroleum products has been established.

Abstract: Magnesium ammonium phosphate (MAP) precipitation has been studied by using magnesium hydroxide and sodium dihydrogen phosphate as precipitators for treating simulation wastewater in which the concentration of ammonia nitrogen is 10.00g/L. The effect of reaction time, pH and precipitator ratio on ammonium nitrogen removal rate has been investigated. The obtained optimum treatment conditions of MAP precipitation for treating ammonia nitrogen wastewater are as follows: reaction time is 4 hours, pH is 8.0, the molar ratio of sodium dihydrogen phosphate and ammonia nitrogen in wastewater, i.e. n (P):n (N), is 1.2, the molar ratio of magnesium hydroxide and sodium dihydrogen phosphate, i.e. n (Mg):n (P), is 1.4. Under these conditions, the ammonium nitrogen removal rate, by using MAP precipitation for treating simulation ammonia nitrogen wastewater, is 90.71%.

Abstract: Based on the investigation of measurement method of ammonium nitrogen (NH₄-N) desulfurization and denitrification wastewater (DDW) by distillation method, effects of pH, Cl/N and the initial concentration of NH₄-N on the removal of NH₄-N in DDW by sodium hypochlorite were studied. Results of parallel test and standard recovery test demonstrated good reliability and accuracy of the distillation method for the measurement of NH₄-N in DDW. The NH₄-N removal efficiency increased with pH from 5.0 and 8.0, and then decreased with pH higher than 8.0. Therefore, the optimum pH value was 8.0 with NH₄-N removal efficiency of 74.7%. NH₄-N removal efficiency was increased from 16.9% to 84.1% with Cl/N molar ratio rose from 1 to 5. The initial concentration of NH₄-N showed insignificant effect on the removal amount of NH₄-N, and the removed NH₄-N was about 12~13mg/L with the addition of 4.86mmol/L sodium hypochlorite.

Abstract: Rice husk charcoal, a kind of new environmentally friendly biomass materials, which is made from rice husk under anaerobic combustion at 300°C, has been increasingly applied to remedy some polluted sites. Rice husk charcoal was employed to investigate adsorption of ammonium in simulated waste water, using once balance method. It is found that ammonium nitrogen in water can be rapidly adsorbed by rice husk charcoal in 2 min with maximum sorption capacity of 2.6 mg/g (Langmuir isotherm adsorption model). The n value of 1.2 in Freundlich isotherm model indicates that the absorbent is very suitable for rapid removal of ammonium from water. In addition, quasi-second order kinetic equation is well suited to describe ammonium absorption with time (P<0.01). The adsorption mechanism is supposed that rice husk charcoal firstly imbibes in water and much swells, and then ammonium ion diffuses into the micro pore structure and redistributes upon a steady state.

Abstract: The nitrogen and phosphate were regarded as the target pollutants in this paper to study the balance of adsorption / desorption to nitrogen and phosphate, the adsorption dynamic characteristics under the action of four kinds of urban rivers and lakes sediments in Beijing as well as the impact of DOM in reclaimed water to absorb nitrogen and phosphate. Results show that: the processes of sorption of nitrogen and phosphate in the four sediments could be described by the Linear and Freundlich models, while the adsorption-desorption goes with hysteresis effect. The adsorption of nitrogen and phosphate were inhibited by DOM in reclaimed water, with an adsorption coefficient K_d decreasing by 0.04% -56.88%, reaching a significant level (confidence level α = 0.05);And DOM increased the nonlinear parameter 1/n, up to 2.20 times at most, resulting in a lower adsorption stable.

Abstract: Ammonium nitrogen pollution is a key factor related to water eutrophication. In our works, biochar adsorption for ammonium nitrogen removal from wastewater has been investigated. Transmission Electron Microscope with energy dispersive X-ray spectroscopy, X-ray diffraction, and Fourier Transform Infrared spectroscopy was performed to characterize the prepared biochar. The optimal solution pH, and coexisting ions effect for ammonium nitrogen removal from wastewater was examined. Surface characterization demonstrated the obtained biochar was coarse, unshaped, irregular, and contained a great deal of carbon. With an increase in solution pH, biochar adsorption amount of ammonium nitrogen was decrease. With an increase in coexisting ions concentration, biochar adsorption amount of ammonium nitrogen was decrease.

Abstract: A model was prepared for the preparation of biochar from the biomass of mushroom residue at different carbonization temperature (350 °C,450 °Cand 550 °C) for adsorption characteristics of ammonium nitrogen in water through different ammonium nitrogen concentration, reaction time, pH and temperature. The investigation result showed that the adsorptive amount of these three biochar substances increased quickly with the initial concentration (0-2 h) and the adsorption equilibrium was reached after 4 hours. The adsorptive amount of these three biochars increased with the rise of pH from 5 to 9. Different temperature preparation of biochar on ammonium nitrogen adsorption increases with the rise of temperature. Different temperature preparation of biochar on ammonium nitrogen adsorption amount is in the order of 550 °Cbiochar > 450 °Cbiochar > 350 °Cbiochar.

Abstract: Corn straw biochar and peanut shell biochar were used as an adsorbent, duly affected by the condition of diverse concentrations of ammonium nitrogen, response times, the pH and temperature levels. The study focused on the adsorption characteristics of ammonium nitrogen by corn straw biochar and peanut shell biochar, which demonstrated that the adsorption rate of ammonium nitrogen by corn straw biochar and peanut shell biochar is higher in the initial response. The adsorption quantity rises quickly and attains equilibrium after 4 hours. The adsorbance, once stable was found to be 753.29mg/kg for corn straw biochar and 1003.70mg/kg for peanut shell biochar.The adsorption characteristics of ammonium nitrogen by corn straw biochar and peanut shell biochar are more fitted to the Freundlich equation (Freundlich adsorption isotherm), within the limits of pH 5 to9. The adsorption of ammonium nitrogen by corn straw biochar and peanut shell biochar increased with the increase in the pH and temperature. The adsorption effectiveness of peanut shell biochar is better than corn straw biochar.

Abstract: In this experiment, we simulated the migration and transformation law of nitrate under the condition of water table rise caused by rainfall in Changping District of Beijing. Two types of experimental apparatus were used in the experiment to simulate the distribution of NO3--N, NO2--N and NH4+-N, which were named soil column 1 and soil column 2. Soil column 2 was under the condition of rainfall and soil column 1 was for comparison. It took 50.3 hours for the experiment during which simples were taken and tested. The test items were the concentration of NO3--N, NO2--N and NH4+-N. The results indicated that (1) In unsaturated zone, the influence of leaching caused by rainfall on the concentrations of NO3--N and NH4+-N were significant. The decreasing range could reach to 95.9% and 90% which means that it was easily to lead to the contamination of groundwater. In saturated zone, NO3--N concentrations were mainly influenced by dispersion and could achieve balance between the dilution and dispersion with the increase of rainfall. The increasing range of NO3--N concentration was large, and the value could reach to 675%. In addition, the NH4+-N concentration had a slight trend of decrease. (2) Under the condition of rainfall, NO3--N concentrations increased in saturated zone, decreased in the path of water table rise and unsaturated zone. The NH4+-N concentrations had a decreasing trend in saturated-unsaturated zone. (3) NH4+-N concentrations in medium sand were more easily influenced by leaching from rainfall than those in silt.