Continuous ion-exchange removal of ammonium ion onto clinoptilolite in the presence of contaminants

摘要

The continuous removal of ammonium ions and other ionic pollutants from waste waters can be successfully achieved, usually after secondary biological treatment operations, by using ion exchange. In actual industrial operations, the presence of small concentrations of other non-ionic or weakly ionic pollutants may exert significant influence upon the ion-exchange uptake of the ionic species. Such effects are of significant importance in the design and specification of ion-exchange treatment systems. The underlying aim of the work described in this paper was to quantify the behaviour of the naturally occurring zeolite, clinoptilolite, during the removal of ammonium ion in fixed-bed ion-exchange columns in the presence of contaminants. There were two specific areas of investigation. Firstly, the effects of interfering species, including the organic compounds citric acid, phenol, hexane, glucose, natural sunflower oil and whey protein, were studied. The effect of the presence of these contaminants upon the column breakthrough behaviour was determined. Secondly, the effect of regeneration upon the ion-exchange performance was measured over a number of uptake/regeneration cycles. The results show that the presence of citric acid had only a small effect upon column breakthrough capacity. The column performance in the presence of whey protein is slightly enhanced. The column uptake performance is significantly enhanced after regeneration over the first four to five cycles of regeneration until a stable exchange performance is attained. The enhancement was also observed in the presence of the contaminants.