Water. desalination + reuse

RESEARCH August-September 2014 | Desalination & Water Reuse | 41 | suggests that DPR might eventually become mainstream in climate-challenged, growing population as more and more successful schemes are implemented, and confidence in this approach grows. SWRO can, on a total project annualised cost basis, be delivered for about the same unit cost as IPR but, on the face of it, is more expensive than the other two reuse scenarios. However desalination offers a significant and unique advantage over all of the other reuse scenarios – it provides a new source of water. Taking losses into account, dual pipe systems might on average meet up to 30% of residential demand, and IPR and DPR up to some 50%. Consequently, reuse schemes still require a continuous, sustainable freshwater source. By contrast SWRO can provide a sustainable source of drinking water in any quantity required and is independent of climate change factors. Managing perceived or real environmental impacts can make a significant difference to costs. For example, SWRO requires management of intake issues, and brine outlets. Reuse projects produce a concentrated waste stream, but avoid the discharge of some wastewater to the environment. This study demonstrates that cost alone is not the sole determinant behind water supply augmentation solutions. Large and growing coastal communities in climate- challenged environments are likely to look to combinations of some of our scenarios References This article is based partly on the outcomes from a study undertaken by GHD (ATSE, 2013 and GHD, 2013). The ATSE study was funded by the Australian Water Recycling Centre of Excellence under the Commonwealth's Urban Water and Desalination Plan. ATSE (2013) Drinking Water through Recycling – the benefits and costs of supplying direct to the distribution system prepared by the Australian Water Recycling Centre of Excellence. http://www.atse.org.au/Documents/ Publications/Reports/Water/drinking-water-through-recycling-full-report.pdf GHD (2007) Using Recycled Water for Drinking – An Introduction. Produced for the Australian National Water Commission, Waterlines Occasional Paper No 2, June 2007. http://archive.nwc.gov.au/__data/assets/pdf_file/0008/11024/ using-recy-water-drinking-body-Waterlines-0607.pdf GHD (2013) Financial and Life Cycle Inventory Analysis of Alternative Water Supply and Recycling Options in Australia – Jun. 2013, ATSE http://www. atse.org.au/Documents/Publications/Reports/Water/appendix-b-hypothetical- comparison-of-four-water-supply-options.pdf Greenhouse gas (GHG) accounting protocols categorize direct and indirect emissions into three broad scopes: scope 1 - all direct GHG emissions; scope 2 - indirect GHG emissions from consumption of purchased electricity, heat or steam; and scope 3 - other indirect emissions, such as the extraction and production of purchased materials and fuels, transport- related activities, and waste disposal. Figure 3. Flow specific GHG emissions breakdown based on product water flow (tCO 2 e/Ml) for the scenarios. to address their water supply needs as they take local characteristics into account. A good example of this is to be seen in Los Angeles' West Basin Municipal Water District's Water Reliability 2020 plan which involves elements similar to each of the four scenarios described here including high-quality recycling direct to industry, dual pipe, desalination, and groundwater recharge through IPR. SWRO and DPR have unique and favourable attributes which we anticipate will lead to their rate of implementation growing as climate change impacts and greater community understanding evolve. ConCluSion Customising water supply augmentation with appropriate technologies to take into account the specific climate, growth and local infrastructure challenges facing a community should lead to a collection of means to secure a resilient and sustainable water supply. l ViSiT onlinE desalination.biz

• Cover