A Salt with Intent

For parched communities, where land-based water has dried up leaving deserts and drought, building coastal desalinization plants is their lifeline toward survival. As climate change hikes global temperatures, taxing water supplies to the max, governments are increasingly reaching to desalinization as their only viable answer. 

By reason of sustained drought, inadequate infrastructure and poor planning, the modern city of Cape Town, South Africa (4 million residents) is running out of water, putting its citizens on a daily ration of 13 gallons per person, the minimum per capita amount of domestic water recommended by the United Nations. Even that paltry supply is about to run out. Cape Town residents “are now limited to using 13 gallons of water per person per day. That’s enough for a 90-second shower, a half-gallon of drinking water, a sinkful to hand-wash dishes or laundry, one cooked meal, two hand washings, two teeth brushings and one toilet flush…

“Cape Town may be the first major city to run out of water, but it won’t be the last. In Mexico City, residents are already experiencing cuts to their piped water supply, and officials in Melbourne (another city affected by drought) warn that the city is little more than a decade away from exhausting current water supplies. At one point, before a sustained deluge in 2015, the city of São Paulo was down to less than 20 days’ worth of water, according to the World Resources Institute, a Washington-based research organization that tracks the use of natural resources around the world. It reports that more than a billion people currently live in water-scarce regions and as many as 3.5 billion could experience water scarcity by 2025 if steps are not taken to conserve water now.” Time Magazine, 1/15/18. Are any of these cities, especially those on the coast, candidates for massive construction efforts toward desalinization (also “desalination”)?

Having experienced some of the driest years on record and with most of her population on or near a seacoast, Australia stepped up big. Here was their vision at the outset: “In one of the country’s biggest infrastructure projects in its history, Australia’s five largest cities are spending $13.2 billion on desalination plants capable of sucking millions of gallons of seawater from the surrounding oceans every day, removing the salt and yielding potable water. In two years, when the last plant is scheduled to be up and running, Australia’s major cities will draw up to 30 percent of their water from the sea. [Most of these projects have since been built and are operational.]

“The country is still recovering from its worst drought ever, a decade-long parching that the government says was deepened by climate change. With water shortages looming, other countries, including the United States and China, are also looking to the sea.

“‘We consider ourselves the canary in the coal mine for climate change-induced changes to water supply systems,’ said Ross Young, executive director of the Water Services Association of Australia, an umbrella group of the country’s urban water utilities. He described the $13.2 billion as ‘the cost of adapting to climate change.’” New York Times, 7/10/10. There are, however, other costs.

The briny salty effluents are toxic. Salt is the byproduct of desalinization even using the most modern systems available. It is a delicate balance, since salt is an essential part of our bloodstreams – vital for life – but excess salinity sucks the oxygen out of oceans. Dead Zones, where most sea life is extinguished due to toxicity, are caused not just by dumping unprocessed industrial pollutants and sewage into the sea but by excess salinity associated with the process of turning sea water into drinking water. 

Still, without desalinization, many major regions of the world simply could not sustain human populations, and it is getting hotter and dryer by the day. For example. Saudi Arabia and its immediate desert kingdom neighbors create one-fifth of the earth’s salt effluents that are dumped into the seas. The technology works, although the oldest plants in the world, still operational, use the most energy and dump the greatest amount of salt.

“There's been a major expansion of desalination plants around the world over the past few years, with almost 16,000 now operating in 177 countries [see the BBC map above]… It's estimated that these plants produce 95 million cubic metres of freshwater per day from seas and rivers - equivalent to almost half the average flow over Niagara Falls… A number of small countries, such as the Maldives, Malta and the Bahamas, meet all their water needs through the desalination process.

“But the success of the technology is coming at a price. This new study estimates these plants discharge 142 million cubic metres of extremely salty brine every day, a 50% increase on previous estimates… That's enough in a year to cover the state of Florida under 30.5cm (12 inches) of brine.

“The problem with all this hyper salty water is that it often contains other contaminants and can pose a significant threat to marine life… ‘The salt level in the sea water is further increased because of this disposal of the concentrate brine,’ said Dr Manzoor Qadir from the UN University Institute for Water, Environment and Health, one of the study's authors… ‘There is an increase in the temperature of this zone of the sea, together they decrease the dissolved oxygen level, which is called hypoxia and that impacts the aquatic life in that zone.’

“Hypoxia often leads to what are called dead zones in the oceans - Scientists say these zones have quadrupled since 1950, mainly as a result of climate change. Now the salt is adding to these problems… ‘High salinity and reduced dissolved oxygen levels can have profound impacts on benthic organisms, which can translate into ecological effects observable throughout the food chain,’ said lead author Edward Jones, at Wageningen University, in the Netherlands.” BBC.com, January 14^th.

Another way to describe “hypoxia” is “a condition in which the body or a region of the body is deprived of adequate oxygen supply at the tissue level.” Wikipedia. The fundamental reverse osmosis process was once among the highest energy-consuming and inefficient processes… with much more in the way of excess salt. “Researchers involved in the study say the problem often originates in the age of the desalination plant. The older, reverse osmosis-based technology often produced two litres of brine for every litre of drinking water.” BBC.

From laying miles of “French drains” (plastic pipes with distant holes to carry and release brine gradually and farther away from the source) to simply improving the process itself, the prospects for converting seawater into potable water with less environmental damage are improving. However, the process is still an energy hog (not as bad, especially if solar power is added to the mix), and briny effluents still cause issues. “The best laid plans of mice and men…” “The laws of unintended consequences…”

              I’m Peter Dekom, and listening to our leaders poo-poo global climate change, as the world adapts a patchwork of solutions to a tsunami of related disasters, makes me think that mankind deserves the fate it is inflicting on itself… except I and my family are… er… part of mankind!