Studies On The Ammonia-nitrogen Removal From Water With Zhaoshan Zeolite

Zhaoshan zeolite is a kind of clinoptilolite newly exploited in Hubei, the study on the zeolite is at an eary stage. This paper mainly studied three aspects about Zhaoshan zeolite: first, the basic performance of ammonia-nitrogen absorption and influence factors on the effect of ammonia-nitrogen removal by Zhaoshan zeolite. Second, the choices of suitable method to make zeolite modified and the effect of ammonia-nitrogen removal by the modified zeolite, Third, immobilizing nitrobacteria and PSB respectively using Zhaoshan zeolite as bio-zeolites and influence factors on the effect of ammonia-nitrogen removal by the bio-zeolite. The experiment results were as follows:Results showed that the cation (NH₄⁺) exchange capacity of the Zhaoshan zeolite was 4.068mg/g, the process of ammonia-nitrogen was fit for the formula of Freundlich. The desorption efficiency was 42.4% after soaked by 1000mg/L NaCl and the desorption efficiency was increasing with the increasing of ammonia-nitrogen absorption.The dosage, treating time, pH and temperature had great influences on the ammonia-nitrogen adsorption. The ammonia-nitrogen removal rate was increasing with the increasing dosage, treating time, pH, temperature in general. In the experiment, treating 20min, pH=6-8, could get a good effect. Increasing temperature could promote the effect only a little(t>25℃).Heating 2.5h at 450℃was the optimum condition for the zeolite modified by heating, at this time the ammonia-nitrogen removal rate was much higher by 12.36% than the Zhaoshan zeolite's; The zeolites modified by H₂SO₄, HCl and HNO₃ were not fit for ammonia-nitrogen removal because of bad effect; The zeolite modified by NaOH of lower concentration (<0.75mol/L) had some good effect, but the process to get the modified zeolite was very difficult with costing great time; The zeolite modified by NaCl had remarkable effect on ammonia-nitrogen removal, the adsorption capacity ofammonia-nitrogen was ten times better than the natural zeolite, and treating 4h at 2.0mol/L of NaCl was the optimum condition for the zeolite modified by NaCl thinking of the factor of technique and economy, and the optimum ratio of (zeolite weight)/(solution volume) was 0.25g/ml.The effect and endurance of zeolite immobilized by nitrobacteria was better than the effect of single Zhaoshan zeolite and single nitrobacteria on ammonia-nitrogen removal. Inoculation dosage, pH, temperature had great influences on ammonia-nitrogen removal. It required a weak alkaline pH and 32 °C. The ammonia-nitrogen removal rate was increasing with the increasing of nitrobacteria inoculation dosage pH and temperature, but would decrease with a superfluous inoculation dosage and pH>8.5, temperature over 32 °C. Moreover lower temperature(<20°C) would be a limited factor for ammonia-niatrogen removal.The effect of zeolite immobilized by PSB was better than the effect of single Zhaoshan zeolite and single PSB on ammonia-nitrogen removal. This showed that the immobiliztion could preserve the avtivity of PSB very well and exert the function of bio-chemical combination on ammonia-nitrogen removal. The ammonia-nitrogen removal rate was increasing with the increasing of PSB inoculation dosage and pH and temperature, but would decrease with a superfluous inoculation dosage, pH>8and temperature over 30 °C.