| With the rapid development of the economy of our country, the pollution of water source is increasingly serious. Ammonia-nitrogen (NH4 + -N) is an important contaminant for eutrophication of water body and environmental pollution. With high concentration of NH4+-N, natural nitration is restrained, water becomes anoxic, fishes are poisoned, and the self- depuration ability of water is reduced. To develop an economical and efficient method to control the NH4+-N pollution has become an important program at the present.As a kind of low-priced nonmetallic mineral, zeolite has good selective adsorption ability for NH4 + -N. Modifying can even increase this capacity. Clinoptilolite and mordenite have much applying prospect in this aspect. The research on NH4+-N removal with natural zeolite is sufficient in many countries. Applying zeolite to treat wastewater containing high concentration of NH4+-N is successful hi industry, but when it comes to the removal of low concentration of NH4+-N, the report is rarely seen. There is an outstanding contradiction hi the removal of NH4+-N and other contaminants in water with zeolite: the smaller gram has higher exchange capacity and better treatment effect, but the zeolite is easy to run off with the effluent and the head loss is greatly increased if the grain is too small. To take larger grain must be price with the sacrifice of exchange capacity.To solve this problem, we began the preparation of modified porous zeolite pellet. First, chose the best modification method of zeolite and the best modifying conditions. Then made the modified porous zeolite pellet and studied its treatment effect of low concentration of NH^-H and CODcr- The factors having influence to NKU+-N removal ratio had been investigated in detail such as pellet size, zeolite amount, treating time, pH, temperature, etc. Finally, the regeneration method and efficiency of zeolite had also been investigated.Through the research of this paper, a conclusion can be drew: NaCl treatment raise the NH4+-N removal ratio obviously by 18%, and is better than treating by heating, H2S04, HC1 and NaOH. The most reasonable concentration of NaCl is 0.8-1.0mol/L considering technical, economic and other factors synthetically; Thebest conditions of NaCl modifying is as follows : temperature 70~75℃, time 2.5hours, granularity < 120mesh, volume/mass 25ml/g; As additive forming pores, activate carbon powder is a little better than charcoal powder, but the effect of both is much better than sawdust. The best preparation conditions of modified porous zeolite pellet is: modified zeolite(-200mesh) : additive forming pores (activate carbon powder or charcoal powder) : binder(soluble starch) = 89:9:2, sintering temperature 600℃, time 2hours.When the made-up modified porous zeolite pellet is used to treat the simulant wastewater containing 10mg/L NH4+-N, zeolite amount being 5.33g/L, activate carbon powder and charcoal powder being additive forming pores, the removal ratios of NH4+-N are 91.9% and 90.34%; As the NH4+-N rises from 5mg/L to 60mg/L, the removal ratio falls from 95.22% to 30.78%; The smaller pellet gets much better effect than bigger ones; The removal ratio increases as temperature goes up. Temperature has great influence to NH4+-N removal in low temperature, but its influence becomes less above 25℃; Along with the handling time increases, NH4+-N removal ratio rises gradually. After 40minutes, the removal ratio reaches more than 90% and tends to stabilize; Acidic condition is adverse for zeolite to remove NH4+-N. When pH=4.0 the NH4+-N removal ratio is less than that of neutral and alkalescent conditions by more than 30%; When the modified porous zeolite pellet is used to treat certain water source containing 3.87mg/L NH/-N and 7.28mg/L CODcr, zeolite amount being 2.67g/L, treating time being 40minutes, the removal ratios are more than 95% and 40%.When the modified porous zeolite pellet is regenerated by NaCl, the economical and effective concentration is 1.0mol/L, best treating time is 3.5hours, After hav...
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