Adsorption Performance of Modified Zeolite Granulation on Ammonia Nitrogen

A nitrogen removal granular material (MZ) was prepared from modified zeolite with the addition of polyvinyl alcohol (PVA) and sodium bicarbonate (NaHCO3). The effects of dosage and initial pH on the adsorption performance of ammonium nitrogen (NH4+-N) were systematically investigated. The results showed that the NH4+-N removal rate of MZ reached 94.0% at an MZ dosage of 5 g/L and an initial pH of 7. The adsorption process of NH4+-N on MZ fitted well with the pseudo-second-order kinetic model and Freundlich adsorption isotherm model. The adsorption was jointly controlled by liquid film diffusion and intraparticle diffusion, with a saturated adsorption capacity of 8.47 mg/g for NH4+-N. Four common coexisting cations exhibited inhibitory effects on NH4+-N adsorption by MZ, following the order of K+ > Na+ > Ca2+ > Mg2+ After five regeneration cycles, MZ still retained an NH4+-N removal efficiency of over 80%. Combined with material characterization results, the adsorption of NH4+-N on MZ was predominantly governed by chemical adsorption via ion exchange, while physical adsorption played a secondary role.