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Smart metering and data analytics enable the implementation of a range of onsite infrastructures for energy, water and waste management to demonstrate the interconnected infrastructure of future smart cities. A smart city funded project in Western Australia is integrating smart metering technology, household participation and data analytics. Better understanding of hybrid water systems at residential scale, as socially accepted solutions to promote water efficiency and economic savings, within the traditional centralised urban water network is achieved. An integrated water model and a system of water credits and debits is developed and tested on a case study for which 10-minute logged water consumption data of its hybrid water system are available for one year. The model is shown to provide a full characterization of the relationship between the household and the water resources, thus assisting with an improved urban water management which promotes the rollout of decentralized hybrid water systems whilst accounting for the impacts on the aquifer as an ecosystem service provider.

The integration of hybrid water systems (HWS) into the traditional supply networks is closely linked to achieving sustainable water provision for ever-expanding urban developments. These systems aim to utilise locally occurring water sources by collecting and using water within a discrete boundary. Alternative water technologies such as greywater and rainwater collection systems can reduce pressure on shallow groundwater resources, lessen infrastructure and maintenance costs of existing water systems by deferring new developments such as seawater RO desalination plants and wastewater treatment plants. Ultimately, large-scale HWS implementation can bring about the creation of a water trading market, either in the form of physical peer-to-peer water trading or via a credit-debit system. This review highlights the social, technical and administrative components and factors involved in establishing sustainable HWS. It describes traditional and future trends in urban water management, that is now guided by Water Sensitive Urban Design and Integrated Urban Water Management approaches. The technical aspects of HWS’, their components, benefits and drawbacks of their implementation are highlighted. Social implications from the viewpoints of water practitioners as well as consumers are discussed. An overview of the economics of hybrid water systems, both in terms of their cost and energy consumption per water unit is provided. Sections on the role of policy makers and governance arrangements for small-scale distributed water systems and an overview of the current status of rural and urban water trading schemes conclude the review.

This paper describes the development and experimental evaluation of a novel bubble column-based humidification-dehumidification system, for small-scale desalination of saline groundwater or seawater in remote regions. A bubble evaporator prototype was built and matched with a simple flat-plate type condenser for concept assessment. Consistent bubble evaporation rates of between 80 and 8814ml per hour were demonstrated. Particular focus was on the performance of the simple condenser prototype, manufactured from rectangular polyvinylchlorid plastic pipe and copper sheet, a material with a high thermal conductivity that quickly allows for conduction of the heat energy. Under laboratory conditions, a long narrow condenser model of 150014mm length and 10014mm width achieved condensate recovery rates of around 73%, without the need for external cooling. The condenser prototype was assessed under a range of different physical conditions, that is, external water cooling, partial insulation and aspects of air circulation, via implementing an internal honeycomb screen structure. Estimated by extrapolation, an up-scaled bubble desalination system with a 114m2 condenser may produce around 1914l of distilled water per day. Sodium chloride salt removal was found to be highly effective with condensate salt concentrations between 70 and 13514S. Based on findings and with the intent to reduce material cost of the system, a shorter condenser length of 75014mm for the non-cooled (passive) condenser and of 50014mm for the water-cooled condenser was considered to be equally efficient as the experimentally evaluated prototype of 150014mm length.

Several simple vapour cooling and pre-condensing concepts were assessed for the purpose of mitigating bubble column vapour temperatures, a critical aspect for the development of a bubble column driven greenhouse desalination system. Particular emphasis was on low-energy demand of the devices, ease of manufacture, low investment cost and technical and operational appropriateness for local people in remote places. Under laboratory conditions, the copper tube type I and II concepts achieved water recovery rates of between 65 and 75%. The water-tank cooled tube achieved 83% condensate recovery, albeit at the cost of large cooling water requirements, whereas the air cooled and passive sleeve-cooled bubble condenser columns achieved condensate recovery rates of at least 50% under favourable ambient conditions. A “self-cooling” effect was observed for the passive sleeve columns that could perhaps be tailored to produce small quantities of potable water in hot and arid regions. The effectiveness–NTU method was used to allow for a meaningful comparison between the devices. While the majority of the tested concepts represented a “single-stage” approach to the humidification–dehumidification cycle, it is stressed that a well-designed latent heat recovery system would be crucial for the economic viability of a bubble greenhouse.

The Bubble-Greenhouse system combines the well established Seawater Greenhouse concept with a novel humidification-dehumidification (HD) process, based on the large air/water interface generated by bubbling air through a water filled column. Multistage bubble evaporators and multistage bubble condensers allow for effective recovery and reuse of latent heat via a heating/cooling circuit throughout all column stages. The system can operate with salinities of 5000-35,000. ppm. Following the HD process, cooled vapour provides the tropical type greenhouse with a humid environment for selected crops. Additional condensation occurs along the greenhouse skin and is gravity-fed to drip line irrigation. Low grade energy options such as solar-thermal, photovoltaic, wind, geo-thermal and salinity-gradient solar ponds provide the energy for the Bubble-Greenhouse. Alternatively, waste heat from diesel power stations nearby can provide cogeneration of electricity and bubble evaporator heat and pressure requirements. Crops grown inside a greenhouse demonstrate a strongly reduced water demand and the closed environment protects crops from insects and diseases. As the technology is conceptually simple to implement, it holds great potential for community participation, empowerment, skills development and capacity building of local people in remote locations.

This review was motivated by the growing need for sustainable water supply technologies in arid lands worldwide. A key driver of this review is to evaluate the potential of presently unused freshwater sources such as from evaporative brine management technologies. In doing so, this paper provides a conceptual building block for innovative water systems in the future with a focus on ecologically, socially and economically sustainable freshwater production. The utilization of solar thermal and wind energy as the principal drivers for brackish and saline water desalination projects provides the link between the technologies and devices that are discussed and evaluated in this review. Of the solar still concepts reviewed, higher productivity rates are achieved with increased optimization of heat and mass transfer processes within the system and productivity is closely linked to the technological complexity of the stills. Water production ranges from 2 to 3 L/m2/day for passive stills up to 100 L/m2/day and more for novel systems with multiple latent heat use. Still–greenhouse systems and seawater greenhouse systems are capable of producing distilled water while providing a vital humid environment for the growth of crops in a greenhouse system. Water production rates of 0.5–2.5 L/m2/day for ‘still in a greenhouse’ systems and up to 55 L/m2/day for seawater greenhouses with improved passive condenser technology can be achieved. Water vapour producing technologies such as wind-aided intensified evaporation, solar dryer technology or the bubble column concept, are assessed for their potential to form part of a novel water desalination scheme.

A bacterial based algal control product was tested in a series of microcosm and tank experiments between October 2008 and March 2009 to evaluate if the product was suitable as a short-term intervention technique for algal bloom management in the Swan-Canning River system. Results from greenhouse-situated, did not suggest that the product’s bacteria significantly reduced nutrient concentrations and the product’s ability to suppress algal growth could not be verified. However, results from experiments utilising larger (1200L) fibreglass tanks found that in both aerated and non-aerated, the product accelerated NH4 and NOx reduction. The product’s application also resulted in PO4 reduction in product/no aeration tanks. Furthermore, the product appeared to suppress algal growth in non-aerated tanks over short periods (several days). Algal growth regularly diminished after application but reappeared shortly afterwards. Aeration had a negative effect on bacterial proliferation in the tanks, possibly through alteration of environmental conditions in the tanks. As a consequence of the environmental conditions in the tanks that were counterproductive to the development of a representative microbial composition, questions regarding the product’s ecological impact could not be assessed satisfactorily in the tank experiments. There was no indication that the product actively attacked or lysed algal cells.