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.

We have only rudimentary understanding of the complex and pervasive connections between water and energy in cities. As water security now threatens energy and economic security, this is a major omission. Understanding the water-energy nexus is necessary if we want to contribute to solving water and energy issues simultaneously; if we want to stop moving problems from one resource dimension to another. This is particularly relevant in the Australian context where energy use for water supplies is forecast to rapidly escalate, growing around 300% from 2007 levels, by 2030. This paper presents a literature review with an aim of characterising the research to date with a particular focus on cities, the major centres of consumption and growth. It systematically analyses a wide range of papers and summarises the diverse objectives, dimensions, and scale of the research to-date together with knowledge gaps. There are many major gaps. These include energy use associated with water in industrial and commercial operations as well as socio-political perspectives. A major gap is the lack of a unifying theoretical framework and consistent methodology for analysis. This is considered a prerequisite for quantitative trans-city comparisons.

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A new approach to sewage treatment which involves rapid clarification of raw sewage with fine magnetite particles is described. The process, which is essentially a greatly accelerated chemical coagulation, provides a quick separation of the sewage into two liquid streams, one clarified, the other highly concentrated. Development of the process up to and including operation of a fully continuous pilot is outlined and potential advantages and disadvantages identified.

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