Study On The Modified Diatomite Absorb Ammonia-nitrogen And Heavy Metal (Chromium)

The ammonia-nitrogen is the main form of nitrogen in water, is the important pollution material leading to rich nourishment of water and pollution of the environment, enter the body of water and can cause the anoxia, stir up the harmful living things of water, cause the fish be poisoned. In addition, when using the chlorine to disinfect water, the ammonia-nitrogen reacts with chlorine,then chloramines is created, lower the disinfection efficiency of the chlorine obviously, increase the demand of the chlorine consumedly. The ammonia changes to nitric acid,the further conversion of nitrate is nitrosamine which has serious function for the human beings, threatenning the mankind's health directly. But the chrome is one of the important microelement that life must have, the toxicity of the chrome has something to do with valence,Cr6+ is a carcinogen with strong toxicity, was easily absorbed by the human body and stored in it, it is also one of the main factors that can cause lung cancer, therefore, the controls of water pollution which contains the chrome and ammonia-nitrogen have already become the most important task of the environment workers nowadays.The diatomite is the biologic quartzite that be constitute by the diatom and the silicon quality remains of the other microorganisms, having the huge ratio surface area and strong surface adsorption. As a kind of new flocculant, the diatomite has extensive sources, good effection of treating sewage and simple equipment for subsequent sludge disposal, so it has a great future for application.The article studies the adsorption characteristic and the mechanisms of modified diatomite which adsorbs the ammonia-nitrogen and the heavy metals (Cr³⁺) from the wastewater (the artificial prepare), using inorganic flocculant,the high molecule organic of flocculant (Polyscrylamide) and zeolite to change the characteristic of diatomite, after that, using modified diatomite to deal with ammonia-nitrogen wastewater. The experiment indicated that category and dosage of flocculant, diatomite dosage, blend time and speed, the temperature of adsorption, the pH value of aqua, the beginning concentration of ammonia-nitrogen about the aqua, etc. are main factors that affect the adsorption characteristic of diatomite to adsorb the ammonia-nitrogen. Within certain scope, adds the quantity of diatomite, prolongs adsorption time and increases adsorption temperature, advances the pH value can improve the adsorption effect of ammonia-nitrogen. But as the increment of the beginning concentration of ammonia-nitrogen, the adsorption rate descends. Changing the characteristic of diatomite can raise the ability of diatomite to adsorb ammonia-nitrogen, the adsorption rate raised from 10% to 30% above. As for the Cr³⁺, it does not need to change the characteristic of diatomite,the rate can attain 90%. Besides, the model of diatomite adsorbing Cr³⁺ matches the Freundlich adsorption isotherms well.