Adsorption Of Ammonia Nitrogen On Silicate Minerals In Waste Water

With the rapid development of the economy of China, water pollution is increasingly serious. Ammonia-nitrogen (NH₄⁺-N) is an important contaminant for eutrophication of water body and environmental pollution. With high concentration of NH₄⁺-N, natural nitration is restrained, water becomes anoxic, fishes are poisoned, and the self-depuration ability of water is reduced. To develop an economical and efficient method to control the NH₄⁺-N pollution has become an important task at the present.Silicate minerals are important nonmetal minerals, they are not only rich in deposit but also low in price. Silicate minerals have excellent physical and chemical properties such as absorption, filt, ration, separation, ion exchange for their sandwich structure, so exhibit wider application prospect in wastewater treatment. The properties and structure of zeolite, palygorskite, bentonite, kaolinite are introduced in this paper, the efficiency of the ammonia nitrogen adsorption in wastewater and demostic farming wastewater sampled is also studied.Firstly, five kinds of samples are selected from twenty seven samples, which have higher efficiency of the ammonia nitrogen adsorption.Secondly, the effect of samples on removal of ammonia nitrogen is evaluated in the condition of different modified methods, such as heated, acidification, inorganic salt, basification modified with NaOH. Comparing the testing results of ammonia nitrogen removal efficiency, it is found that best removal efficiency obtained by NaOH modified samples than other modified samples.Thirdly, the adsorption characteristics of the natural samples and the modified samples are analyzed based on ammonia nitrogen adsorption isotherm and dynamics analysis, characteristic and pH are also considered. Results show that the surface area of the modified samples is bigger than that of the natural samples.The effect of pH is examined over the range 1.5-11. The adsorption of ammonia nitrogen increases with increasing pH, the adsorption of ammonia nitrogen reaches a maximum at pH 2.5-9, and the adsorption of ammonia nitrogen decreases at higher pH. The modified samples have higher ammonia nitrogen adsorption capacity, with the higher q_m At last, the natural and the modified samples are used to remove ammonia nitrogen from demostic farming waste water with the 19.82mg/L concentration of ammonia nitrogen. Results show that the modified samples have the higher removal effect of ammonia nitrogen: the removal rates of ammonia nitrogen on modified samples ZL-1, ZL-4, AP-2, AP-10 and the bentonite are 84.5%,87.1%,83.5%,72.8% and 91.0% respectively.