Study On The Zeolite’s Treatment To Ammonia Nitrogen In Domestic Sewage

With its ion exchange adsorption performance, zeolite is a significantadsorption material to the sewage treatment in modern life.This subject adopts thedischarged sewage of septic tank in Chongqing Traffic Research Designing Institute asthe research object, discusses the removal of ammonia nitrogen of zeolite, which aimsto reduce the ammonia nitrogen concentration in the sewage and improve ammnonianitrogen adsorption rate of zeolite.First of all, the influential factors of natural zeolite inthe ammonia nitrogen wastewater treatment were studied, including the influence of thefactor variations of particle size, amount, adsorption time, pH value,initial concentrationof ammonia nitrogen,wastewater’s COD on the ammonia nitrogen adsorption capacityof natural zeolite, and made a comprehensive optimization of the various parameters;second, adopted several kinds of commonly used modification methods to actzeolite,including the inorganic acid(hydrochloric acid and sulfuric acid), inorganicalkali(sodium hydroxide and potassium hydroxide),inorganic salt(ammonium chloride,potassium chloride, calcium chloride，sodium chloride)’s modification experiments onthe natural zeolite, coparing the removal effect of ammonia nitrogen on the wastewatertreatment between the modified zeolites; third, studied the dynamic experiment ofsodium chloride modified zeolite on the ammonia nitrogen wastewater, respectivelydiscussed the influence of the water flow, packed column height of modified zeolite andammonia nitrogen concentration of raw water on the modified zeolite’s ammonianitrogen treatment in the wastewater.According to the static experiment results, ammonia nitrogen removal effectof natural zeolite relates to the factors of zeolite particle size, zeolite dosing quantity,initial concentration of ammonia nitrogen,adsorption time and pH value.The ammonianitrogen absorption rate of zeolite with comprehensive optimization have certainenhancement,reaching62.58percent, and COD in the wastewater have little impact onthe process of ammonia nitrogen abosorption,which can be ignored. When thehydrochloric acid concentration is0.1mol/L,the ammonia nitrogen removal effect ofhydrochloric acid modified zeolite is relatively good, ammonia nitrogen absorption rateis77.76percent; the best dosing quantity of hydrochloric acid modified zeolite on the500ml wastewater is50g.When the sulfuric acid concentration is0.06mol/L, theammonia nitrogen removal effect of sulfuric acid modified zeolite is relatively good, adsorption rate is73.22percent; the best dosing quantity of sulfuric acid modifiedzeolite on the500ml wastewater is50g.Ammonium chloride and inorganic alkali(sodium hydroxide and potassium hydroxide) modified zeolites’ effect of ammonianitrogen wastewater treatment is poor, even lower than the process ability of naturalzeolite, which are not suitable as natural zeolite modifying agents. After calciumchloride and potassium chloride’s treatment to zeolite,ammonia nitrogen removal abilityhave improved.The modification effect of potassium chloride is higher than that ofcalcium chloride. The effect of sodium chloride modified zeolite on the treatment ofammonia nitrogen wastewater is much better,0.7mol/L sodium chloride modifiedzeolite can reach86.93percent of ammonia nitrogen absorption rate. When themodifying time of0.7mol/L sodium chloride modified zeolite is4h, and the modifiedzeolite dosing quantity reaches50g, the ammonia nitrogen absorption rate of modifiedzeolite on the treatment of500ml wastewater can reach91.66percent.According to the dynamic experiment’s result, the faster the wastewaterflowes by the packed column, the higher ammonia nitrogen concentration will be in thewater. With the increased amount of wastewater, the ammonia nitrogen adsorptionability of zeolite packed column have gradually declined. The effluent ammonianitrogen concentration reached discharge standard with the flow rate of0.25L/h. Thehigher zeolite packed column is, the water ammonia nitrogen concentration is lower,removing ammonia nitrogen is more efficient.The maximum capacity of ammonianitrogen wastewater treated by modified zeolite with10cm filling height is4L. Themaximum capacity of ammonia nitrogen wastewater treated by modified zeolite with20cm filling height is7L. The maximum capacity of ammonia nitrogen wastewater treatedby modified zeolite with30cm filling height is11L. Increasing the zeolite packedcolumn height could prolong the use time and delay the ammonia nitrogen adsorptionreaction balance. In the initial stage, the ammonia nitrogen concentration of raw waterhas little influence on the adsorption of ammonia nitrogen, at the late time the ammonianitrogen concentration is increasing with the concentration of raw water increased, andthe ammonia nitrogen adsorption ability of the zeolite packed column has graduallydeclined. The maximum capacity of30-50mg/L ammonia nitrogen wastewater treatedby zeolite packed column is10L. The maximum capacity of50-70mg/L ammonianitrogen wastewater treated by zeolite packed column is8L. The maximum capacity of70-90mg/L ammonia nitrogen wastewater treated by zeolite packed column is5L.