Ammonia removal from sewage using natural Australian zeolite

A rapid adsorption process, which utilises the ammonium ion selectivity of a natural Australian zeolite, is being developed for removal of ammonia from sewage. The study reported in this paper claims not to have invented nor discovered this technique of ammonia removal from wastewater, but aims to realise the value of this natural Australian resource as an efficient alternative to existing treatment processes. An understanding of the equilibrium and kinetic behaviour of this material provided insight into its expected capacity as an adsorption media. Favourable results led to pilot scale trials, which revealed excellent performance of the zeolite under continuous column operation. The zeolite adsorption process has proved effective, at pilot scale, in reducing ammonium ions in sewage from concentrations ranging from 25 to 50 mg NH₄-N/L down to levels below 1 mg NH₄-N/L. Under optimised operating conditions, the adsorption capacity of the zeolite for this range of influent ammonium concentrations was about 4.5 mg NH₄-N/g. The rate of treatment by the pilot zeolite column makes it ideally suited as a retrofit to high rate secondary sewage treatment processes, for removal of the soluble ammonium component.