Modification Of Zeolite And Its Capping Technique Of Sediment

The technique of capping zeolite can not only inhibit the release ammonia fromsediment to overlying waterbody, but can eliminate part of the nitrogen load in thesediment. So, it is an effective way to control of internal pollution of the river (lake)sources. It is very important that adsorption ability to ammonia and rate of situregeneration by a modification of zeolite. In this study, Na+modified zeolite is the mainmaterial. The characteristics of adsorption ammonia nitrogen by modified zeolite, itssitu regeneration and eliminating of nitrogen load were studied. The main experimentalresults were as follows:1. For zeolite four modifications such as high temperature roasting, UV irradiation,micro-wave radiation, adding cationic were studied. The results showed that addingcationic is optimum modification because adsorption ability to ammonia increasedto3.08mg/g after modification, which is1.34times than ordinary zeolite.2. Optimal modification results show that the optimal Na+concentration is1.0mol/L,temperature is28℃, and15g of natural zeolite was added in the Na+of200mLsolution. Under this optimal modification condition, porosity, surface area ratioincreased than before. Movever, it was calculated that surface area increased1.71times. The adsorption of ammonia of modified zeolite increases to3.08mg/g. It was1.35times than Ordinary zeolite.3. When modified bio-zeolite was capping on sediment,84.5%of total nitrogen in theoverlying water were removed. Under the same cover density, the elimination oftotal nitrogen in the overlying water is62.8%and71.4%when zeolite and modifiedzeolite were covered on sediment.4. Capping modified zeolite for repair of sediment, the removal efficiency of total nitrogen is64.98%,85.22%,88.87%when in three different coverage density(1.05kg/m~2,2.09kg/m~2,3.14kg/m~2). It suggestd that the reduction of total nitrogenincreased with coverage density of modified zeolite.5. When DO was3.0mg/L and5.5mg/L in the overlying water, the former of releaserate of ammonia is1.49times of the latter. That is to say the release rate of ammoniaincreased at high DO in the overlying water. The removal efficiency of totalnitrogen up to91.65%under capping modified bio-zeolite when DO was control to8.5mg/L in the overlying water.6. Situ regeneration rate of modified bio-zeolite was85.74%, the other were69.12%and54.29%of modified zeolite and ordinary zeolite.