抄録
Ammonia-selective zeolite “clinoptilolite” was used to remove ammonia-nitrogen from synthetic river water which also contains Na+, K+, Ca2+ and Mg2+ ions. Ammonia-nitrogen between 1.5[mg/l] and 3.5[mg/l] was completely removed from the synthetic water though the above competing cations were present. During service period of an ion-exchange column, 1500-1700 Bed-Volume of water containing 1.5[mg/l] NH4+-N was applied before experiencing a break-through. The applicable water volume was reduced to 900-1100 BV, however, when the influent NH4+-N concentration was raised to 3.5[mg/l]. Two models, i. e. the equilibrium model and the non-equilibrium meodel, based on the independent characteristics of selectivity coefficients of an arbitrary pair of cations, were presented to predict effluent cation concentrations. Both models showed good agreement with experimental results, whereas, within the range of this experiment, the equilibrium model seemed to be superior because of its simplicity. Once an ion-exchange column had experienced a break-though, regenerating solution containing 0.3N NaCl was passed through the zeolite bed and, then, introduced to the nitrification-denitrification reactors. After a short period of bacterial acclimation to salinity, more than 95% of NH4+-N in the waste regenerant was removed biologically, giving evidence to the effectiveness of the proposed process.
