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Middle East desalination: It’s important to clean up the brine after desalination, says editorial; plus more details on Middle Eastern desalination procedures

Posted by: Aqua Blog Maven on June 16, 2009 at 7:45 am

Yesterday, I posted an article from the Middle East’s Gulf News about desalination and the problems the brine discharge is causing in the Arabian Gulf. The link was sent to me by a reader who questioned what the implications of the news story might be for California.

Today there is another story posted on desalination in the Arabian Gulf, which brings up an important difference between desalination in the Middle East and what is being proposed for California. The proposed desalination plants for California would use reverse-osmosis; however, most desalination (90%) in the Middle East is done thermally – they boil the water to evaporate it, leaving the salts behind. This creates a hot brine discharge, which accounts for why the temperature of the Gulf waters rises 10 degrees Celsius (as reported in yesterday’s story.) The brine also contains anti-scalants; I do believe anti-scalants are used in Reverse Osmosis desalination – to what degree this differs in the different processes, I do not know.

Keeping this difference in mind, here’s the story from Gulf News:

Desalination is the only way that the countries around the Arabian Gulf will have enough water for their needs since they have neither rain nor rivers, and their aquifers are being sucked dry.

However, desalination brings serious dangers for the marine environment, which have been overlooked for decades as the UAE, Qatar, Bahrain, Saudi Arabia, Kuwait and Iran have gone ahead and built 120 desalination plants to date.

The process of desalination involves boiling sea water so that fresh water steams off, leaving highly salty brine behind, which is pumped back into the sea. There are three problems with this brine …

First, it is very salty, so that year after year the salinity of the Gulf is rising. Second, it is hot, so that the temperature of the Gulf is being raised. Third, the brine contains an alarming volume of chlorine, antiscalants and copper, which are being dumped into the sea.

Read more of this story from Gulf News by clicking here. Find out more about desalination in the Arabian Gulf in this related article from Gulf News: Desalination: Facts and procedures

June 16, 2009 · Filed Under Desalination

Comments

One Response to “Middle East desalination: It’s important to clean up the brine after desalination, says editorial; plus more details on Middle Eastern desalination procedures”

  1. H2AU on July 6th, 2009 11:37 pm

    These are interesting observations in the Gulf region, however they are the exception rather than the norm.

    Firstly, the majority of new desalination capacity being installed uses the seawater reverse osmosis (SWRO) process, which does not significantly raise the temperature of the processed water. Secondly, some chemicals are used in the SWRO process (depending on the site and application), however not in significant quantities, and typically they are FDA approved, and easily neutralised before discharge with the brine reject.

    Furthermore, considering the location of the Gulf, it is not an area of open ocean, so the brine may have a tendancy to concentrate in the local area of each plant’s brine discharge if ocean currents are not able to dilute the brine and carry it away. Brine ploom modelling is necessary during project planning, to determine the optimum brine discharge position and diffusion.

    Compare this with a modern SWRO plant, close to open ocean. The brine diffuser at the Kwinana desalination plant (Perth, Australia) enables the salty brine to be diluted and returns to normal seawater concentration within just a few square metres of the site. In fact, even on the brine diffuser there is evidence of a thriving marine ecosystem. A video is available here: http://www.watercorporation.com.au/_files/mmedia/Under_the_Surface_small.wmv

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