There is an increasing global shortfall of freshwater (also referred to as drinking water or potable water) versus demand. This shortfall is projected to be at 40 percent by 2030, and close to four billion people will live in areas of high water stress (WRG 2012). Therefore, governments, the private sector large and small, and civil society must use and manage water more efficiently.
Agriculture is the largest consumer of water, followed by energy-generating technologies (ES & T 2010; Schelmetic 2012). Agriculture accounts for about 70 percent of annual global freshwater withdrawals and up to 90 percent in some parts of Asia. However, governments across Asia will also need on average 65 percent more freshwater withdrawals for their industry and energy sectors by 2030 in order for their national economies to grow as forecast (WRG 2012).
The energy sector accounts for 15 percent of the world's water use (IEA 2012). Water is critical for electricity generation. Thermoelectric power plants account for almost fifty percent of all freshwater withdrawals in the US (Kenny et al. 2009) The extraction, transport and processing of fossil fuels requires enormous amounts of water. Moreover, unconventional oil and gas production by methods such as hydrofracking are water-intensive, and has markedly increased over the past five years. Water shortages in India and the United States, among other countries, have limited energy output in the past two years (IEA 2014).
RESULTS AND DISCUSSION
The international agriculture and energy industries, whether funded by governments or the private sector, can significantly reduce the use of freshwater by installing relatively simple and proven water treatment systems that use stormwater, reclaimed water, greywater, and rainwater to replace drinking water use. Although the treatment systems will require an initial capital cost, in many cases this capital cost will be recaptured within several years of installation. Cost recapture will be accelerated where treatment systems service entities that require over one million gallons per day (gpd) water, such as food processing (e.g., sugar) (Sugarcane.org 2013; Gerbens-Leenes and Hoekstra 2009), coal-fired power plants (DOE 2007), pulp and paper mills (EPA 2008), steel mills (UMN 2011; IPST 1995), and data centers (Miller, R. 2011).
Desalination and reclaimed water have higher treatment costs, yet their supply may be reliable in times of drought and provide critical supply (Pacific Institute 2014).
Water Reuse Definitions. Reclaimed water, or recycled water, is defined as former wastewater that is treated to remove solids, impurities and pathogens; meets water quality requirements; and is reused for applications such as irrigation, industrial cooling, and aquifer recharge.
Greywater is defined as wastewater that has been used in kitchen sinks, baths, showers or washing machines. It does not include discharge from toilets, which contains human waste; such waste is termed sewage or blackwater.
Case Studies. A South African wastewater treatment plant (cost: $2.9M US) treats approximately 500,000 gallons per day (gpd) water, utilizing reverse osmosis and enabling the factory to operate without the use of any outside water sources. (WRG 2013).
A Namibian wastewater treatment system generates 4.7M gpd reclaimed water through ozonation, flash mixing, enhanced coagulation and flocculation, sand filtration, and carbon filtration. The cost of production is virtually the same as the cost of potable water coming from the existing surface water storage (WRG 2013a).
A component of Microsoft's data center in Washington USA includes the construction and operation of a water treatment plant that employs reverse osmosis and reuses the water from the local farming community's food processing plant (Miller, R. 2011).
Irrigation Improvements. A variety of irrigation and infrastructure improvements have proven successful in saving substantial amounts of water in arid areas including Saudi Arabia, Australia, India, South Africa and Mexico (WRG 2013a):
a) replacement of leaky pipes and fittings, pressure management through automated leak detection, and installation of pressure-regulating valves;
b) industrial water metering; low-flow showerheads, taps, and toilets;
c) irrigation scheduling to maximize yield, installation of sprinkler irrigation systems, and enforcement of quotas;
d) replacement of irrigation channels with pipes or lining of irrigation channels, installation of soil moisture probes and computerized monitoring of soil moisture.
The impending global shortfall of freshwater can be lessened by industry and government implementation of existing water treatment technologies, which can not only pay for their capital costs over several years but reduce operating costs over the medium- and long-term.
1. DOE 2007. Use of reclaimed water for power plant cooling. Department of Energy -- Argonne National Laboratory. ANL/EVS/R-07/3.
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9. Miller, R. 2011. Microsoft to slash its water impact in Quincy. Data Center Knowledge
10. Pacific Institute 2014. Desalination and alternative supplies. Pacific Institute website. www.pacinst.org.
11. Schelmetic, T. 2012. Down the drain: industry water use. http://news.thomasnet.com/IMT/2012/04/10/down-the-drain-industry-water-use/
Thomasnet News. April 10.
12. Sugarcane.org 2013. Mills in south-central Brazil processed 42.84 million tons of sugarcane in the first-half of September. http//www.sugarcane.org website. September 25.
13. UMN 2011. Water use in pulp and paper mills. University of Minnesota Technical Assistance Program. www.mntap.umn.edu/paper/water.html. April11.
14. WRG 2013. Water recycling in the food sector, Durban, South Africa. Water Scarcity Solutions, 2030 Water Resources Group. Washington, D.C. August.
15.WRG 2013a. Water Scarcity Solutions, 2030 Water Resources Group. Washington, D.C. August.
16. WRG 2012. The Water Resources Group, background, impact and way forward. 2030 Water Resources Group. Briefing report prepared for the World Economic Forum Annual Meeting 2012 in Davos-Klosters Switzerland. 26 January.