Desalination plant design addressing green concerns

Dubai: The International Desalination Association president is confident that existing water purifying technologies in the UAE are adequately mitigating desalination impacts on the marine environment.

Likewise, seawater quality affected by oil spills or red tide has not hindered water security, said Lisa Henthorne, chief technology officer from Water Standard and President of the International Desalination Association (IDA).

The design of modern desalination plants demonstrate minimal to no impact on the environment, as demonstrated by the monitoring results from these plants, she said.

The IDA does not personally conduct studies but some desalination plants around the world monitor their own environmental data and publicly report the results of that data, Henthorne told Gulf News via an email interview.

The UAE Minister of Environment and Water, Dr Rashid Ahmad Bin Fahd stated earlier that the provision of a sustained water supply is one of the major challenges the UAE is facing under the current economic development, urban expansion and increase in population.

Desalination is proving to be a double edged sword for regions with severe water scarcity that are almost entirely dependent on desalinating sea water. The hazard of marine-originated pollution to desalination plants is another challenge, Bin Fahd added.

A Gulf News report earlier revealed how desalination plants pump out tonnes of metals, chemicals and chlorine into the ocean as a result of desalinating more than 12 million cubic metres of sea water annually. The UAE, Qatar, Bahrain, Saudi Arabia, Kuwait and Iran have 120 desalination plants between them that flush nearly 24 tonnes of chlorine, 65 tonnes of algae-harming antiscalants used to descale pipes, and around 300 kilograms of copper into the Arabian Gulf every day.

Reappearing red tide over the last year across the UAE coastline - resulting in increased algae of a reddish colour, killing off fish and coral - was one of the biggest threats to desalination plants, some of which were forced to close in Ras Al Khaimah and the northern emirates.

Henthorne said there are mitigating technologies which can manage the influence of red tide and which have been successfully demonstrated in the UAE, but not all membrane desalination plants are equipped with this technology yet, she added.

"The red tides have caused some membrane desalination plants to temporarily shut down&Historically red tides are an infrequent problem and plants have been able to manage around them but the last year has seen an exceptional frequency and severity of red tide events."

Desalination effluents are typically 10C higher than sea temperature and environmentalists argue this can have a negative impact on marine ecosystems.

Desalination plants can be designed and operated with very negligible environment and marine impacts, said Henthorne.

"Monitoring programmes are also important to ascertain and ensure the health of the marine environment. Countries such as Australia and the United States are particularly proactive in ensuring these design and monitoring practices be included in the development and operation of desalination plants.

"Significantly increased temperatures over a long period of time could change the marine populations in a designated area. Monitoring studies can be implemented to protect against this occurrence," she said.

"There have been many changes to desalination plants that greatly lessen their impact on the environment& One thermal process that has been growing in popularity in the UAE uses less electrical energy and is also much less likely to produce copper by-products than some of the older facilities.

"There is also a growing trend to use reverse osmosis membrane technology in the Gulf which &typically use much less chlorine and have much lower energy requirements."

Meeting: Tackling impact
The International Desalination Association (IDA) World Congress on Desalination and Water Reuse will be held from November 7 to 12 in Dubai, organized by the International Desalination Association, hosted by TechnoPark and supported by Economic Zones World.

Under the theme "Desalination for a Better World", the Congress will address environmental and energy impacts of desalination, trends and advances in the industry.