Ammonium ion (NH₄⁺) removal from secondary effluent through ion-exchange: the effect of biological activity and the presence of other cations

This paper is concerned with ion-exchange removal packed bed studies carried out with secondary effluent on a sewage treatment works. The work was carried out over a five month secondment period with Severn Trent Water, situated in the midlands of England. The objective of the work was to compare previous studies with clinoptilolite using synthetic wastewaters, de-ionised water and appropriate salts, with typical process water found on a sewage treatment plant. Experimental results have shown ammonium removal of 90% and greater of the influent NH₄⁺ concentrations. In this report it has been shown that the biological activity of nitrification takes place during the upflow processing of wastewater through the packed beds. It is also shown how other cations cause an inhibitory effect on the ion-exchange process whereas biological activity leads to improved efficiency.