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Brackish water use for food and drink grows in demand, report says

Jan. 22, 2018, Cambridge, U.K. ­– An estimated one quarter of all desalinated water currently comes from inland brackish water desalination technology, which has high potential for food production and drinking water supply, suggests a new report from IDTechEx.

Agricultural use is currently responsible for 70 per cent of all fresh water consumption, but fresh water is becoming more expensive and scarce, indicates an industry report by IDTechEx.

Desalination is mainly applied to sea water since that is 97-98 per cent of the water on Earth, but it is expensive, the report says. There is limited scope for desalinating salty lakes.

Israel, Jordan and the Palestinians are working on a project to make drinking water from the ocean and put the other 50 per cent of the output – the strong brine – into the Dead Sea to get it back to former levels.

Brackish water (0.5-5g/liter salt, one quarter of seawater concentration) is much more attractive because it is 100 times more abundant than salt lakes, IDTechEx reports. Desalination of brackish water takes less energy than desalination of seawater and most of it emerges clean, whereas only a minority of seawater emerges clean in desalination, according to the report.

There are about 325 brackish ground water desalination plants in the United States. The International Desalination Association reports that desalination of brackish water is growing internationally, with an increase of 29 per cent in contracted capacity for the first half of 2017. The typical brackish water desalination plant is for smaller utilities and industrial users, meaning small and medium-sized plants. China accounted for a large portion of growth in these plants, especially during the second half of 2016. The use of desalinated ground water is expected to grow. Supplier Veolia estimates that roughly one quarter of all water desalination demand is currently for inland brackish water desalination technology.

Another option for using brackish water is biosaline agriculture, a relatively new way of dealing with salinity in agriculture. It develops cropping systems for saline environments, using the capacity of certain plants to grow under saline conditions such as quinoa, mustard, sesbania, safflower and triticale and appropriate genotypes of sorghum, pearl millet and barley. Sesbania is an alfalfa replacement. Triticale, a hybrid of wheat and rye, is used as a feed crop for cattle, swine and poultry and it can be used as an alternative for corn and soybean. Halophytes such as switchgrass even produce better under saline circumstances.

Vegetable food also is grown in seawater. Examples are salicornia, mangroves, seawater grasses, kelp specifically and they are variously used in livestock, pet and human food. Brackish water is often available far away from the sea in aquifers and marshes. Many arid and semi-arid areas do have sources of water, but the available water is usually brackish. Brackish water also takes the form of drainage water from irrigated agriculture, excess water from oil production, geothermal plants, as well as waste water from industrial use and from intensive fish and shrimp farming.

Researchers such as International Center for Biosaline Agriculture have worked on key annual conventional crops, such as sorghum, pearl millet and barley. The process of selection for both salt- and drought-tolerant genotypes led to large-scale adoption in many countries in Central Asia, Middle East, North Africa and Sub Saharan Africa.

“Brackish-water irrigation does not have to result in increased salinization of the soil though sometimes farmers must use water from a rainstorm to carry salts back down to below the root zone,” IDTechEx CEO Raghu Das said. “Accordingly, perhaps this story can even go full circle. Areas with almost no water, brackish or otherwise, could be irrigated with partially desalinated seawater at much lower cost than full desalination and all those wonderful salt-tolerant crops grown. Cost will be particularly low when the desalination plants used for any purpose are entirely zero gaseous emission, making all their electricity from wind, sun and/or water power.”

These issues are covered in the new IDTechEx report “Desalination: Off Grid Zero Emission 2018-2028,” which predicts off-grid zero emission desalination, including for brackish water, will be a $35-billion market in 2028. It examines new desalination and electricity technologies that will boost performance and reduce cost, in particular the two reducing what is usually the largest cost element – electricity.

The report breaks down the market and analyzes future desalination options and reasons certain ones are dying out, making the argument that mobile desalination plants will sometimes double as transport, provide electricity for farm robots and replace increasingly unaffordable diesel generators expensively modified to meet new emissions laws.