Studies On The Ammonia-nitrogen Removal From Wastewater With Modified Zeolite

Growing shortage of freshwater resources, while water demand is growing.plenty of industrial waste and sanitary sewage with high density of ammonia nitrogen pour into water bodies, which caused the drop of water source's quality, eutrophication of water body and serious environmental pollution.with high concentration of NH3-N, the conventional biological treatment is restrained,and the ammonia-nitrogen index is high.higher nitrogen content makes the activated sludge biological treatment process was inhibited, the effluent ammonia concentration can not reach the emission standards.In this experiment, we take river northwest of Taiyuan in central sewage treatment plant after pretreatment of wastewater grit chamber for the study, use hunyuan zeolite remove the ammonia nitrogen to decrease ammonia nitrogen concentration to let up a A discharge standards. First, we studied the influencing factors of Hun Yuan zeolite to remove ammonia nitrogen,including the dosage of zeolite,particlesize,reaction time,pH,initial ammonia concentration and optimization of factors.Second,we taked the static expement to compare several modified methods,such as:heating(at different temperature), treating with acid(hydrochloric acid, sulfuric acid and nitric acid), base(sodium hydroxide), salt(ammonia chloride and sodium chloride with different concentration and for different time),choose the best modifying method and condition of zeolite.Finally,we discussed the influencing factors of NaCl modified zeolite to remove ammonia nitrogen in small dynamic experiment.The experiment indicated:for removal of ammonia nitrogen in water modification of zeolite by heating or treating with acids or salts(except odium hydroxide and ammonium chloride)have obvious effect.Compare to the other temperature, hot modified zeolite has better removal effect of 30-60mg/L ammonia nitrogen at temperature of 300～600℃,and the best performance can be abtained at 500℃,the elimination rate reaches as high as 75.2%;The O.1mol/L hydrochloric acid modified zeolite is the best method to remove the 30～60mg/L ammonia nitrogen in wastewater,the best quantity is 20g/L,the elimination rate reaches 97.1%;The nitric acid modified zeolite to remove the 30～60mg/L ammonia nitrogen when the HNO3 concentration is 1.0mol/L,the zeolite quantity is 25g/L,ammonia nitrogen elimination rate is 91.1%;The sulfuric acid modified zeolite to remove the 30-60mg/L ammonia nitrogen when the H2S04 density is O.lmol/L, the modified zeolite quantity is 30g/L, ammonia nitrogen elimination rate is 91.4%;The sodium chloride modified zeolite in the sodium to remove30-60mg/L NH3-N from wastewater when chloride density is 0.6mol/L, the modified time is about 3h, the quality is40g/L,ammonia nitrogen elimination rate is 95.9%.During the small dynamic experiment,we discussed the influencing factors of NaCl modified zeolite to remove ammonia nitrogen,including flow rate,COD concentration,temperature and the height of zeolite column.The results showed that flow rate had a great effect on the ammonia nitrogen adsorption, As the flow rate increased,the speed of penetration accelerated,and the adsorption capacity of ammonia nitrogen reduced.If we increased the height of zeolite column,its working hours would be extended.COD concentration and temperature range from 10℃to 20℃had no effect.