Environmental considerations

This part of the presentation addresses environmental considerations related to desalination. Large-scale seawater desalination projects are now being developed in locations where they never had been previously considered. In the last eight years, plants have begun to be developed and constructed in Australia, Europe, India and the US. Some of these projects are located on extremely environmentally-sensitive seacoasts. Meanwhile, plants in the Middle East are growing ever larger in size. As the number and size of these facilities increase, so does the potential for impacting the environment.

Next, the process of mitigating environmental impacts begins with siting of the desalination plant. Then, because thermal and membrane processes each have a unique set of potential environmental impacts, even the desalination process itself must be considered. Heat used in thermal processes, for example, is an example of the potential environmental impacts that must be mitigated for each type of plant.

Unfortunately, no two locations or plants are exactly alike, and most new projects require several years of study, modelling, and pilot testing before the design and construction can move forward. These studies extend the time and cost of a project, and the resulting mitigation methods may further add to the project schedule and cost.

Not only are some prospective sites located in environmentally sensitive areas, the environmental sensibilities of the local community may be such that they aggressively and vocally oppose any project that could result in further development or growth. While we applaud efforts to safeguard the environment, some of this opposition is, unfortunately, based on inaccurate or incomplete information. It is up to the desalination industry to explore the issues, address concerns, present the facts and help set the record straight so that all stakeholders are able to make informed decisions.

Protection of marine life is, of course, a key concern. From the point that seawater is withdrawn, to the location and method used for concentrate disposal, the impact on marine flora and fauna must be considered. Seawater intake and outfall alternatives must be evaluated by groups of specialists that include marine biologists and toxicologists, hydrogeologists and oceanographers.

Seawater intake options include offshore intakes, sub-seabed intakes, co-located intakes, and passive intakes. Habitat restoration – the process of restoring an area equivalent to that impacted by an intake or outfall – is another alternative that has been proposed at some locations.

Concentrate discharge options are still one of the most obvious concerns. Fortunately, there are a number of options that can be employed to reduce the impact of concentrate discharge, and there are new technologies that offer the promise of further reductions. These options include multi-port diffusers; co-located, blended discharges of cooling water and wastewater effluent; deep well injection; evaporation and salt/mineral recovery; and new technologies such as forward osmosis.

The desalination industry has also done much to decrease energy consumption and significantly reduce greenhouse gas emissions. It is a fact that seawater desalination requires significant amounts of energy. However, in the last 15 years, energy requirements have been reduced by up to 50 percent as a result of technological improvements. Numerous research projects are under way that promise to further reduce energy requirements, including projects that creatively couple desalination plants with wind, solar or wave energy sources to provide the required energy input.

Monitoring programs are another important step in environmental responsibility. Many new plants in Australia have instituted significant monitoring programs to assess the impact of new plants. Not only does this data ensure that the plant is being operated in an environmentally responsible manner, it will provide important information that can be used to aid in the design of future plants.

The Kwinana plant in Perth, Australia is an excellent example of an environmentally responsible desalination. Australia’s first large-scale seawater desalination plant, this facility was commissioned in February 2007. Despite being constructed on a fast track schedule, the project is a showcase for almost every environmental mitigation measure currently considered state-of-the-art. Extensive environmental studies preceded construction, and continuous, real-time monitoring since startup has demonstrated the plant’s ability to operate without adversely impacting the environment.

The International Desalination Association (IDA) is organizing an Environmental Task Force that will examine the world’s best practices and address some of the unique issues facing desalination issues in the GCC countries with an objective of ensuring the sustainability of this important resource. This program is the start of a global initiative by IDA to explore the effects of desalination and recommend strategies for mitigating potential environmental impacts.

It is fitting that the Task Force focuses initially on the Middle East, inasmuch as this region is the home to the greatest concentration of seawater desalination plants in the world. Since large-scale seawater desalination was first introduced to the region in 1959, more than onehalf of the world’s installed capacity is located in the region, and most of its plants are located on the Arabian Gulf.

To recap:

• Proper siting, design and operations will minimize environmental impacts.
• Better environmental regulations and permitting requirements are needed to identify relevant local concerns and formalize mitigation criteria.
• New technologies hold promise for future improvements.

All of this comes at a cost, however, and it is likely that water costs will be impacted. But the alternative would be far more costly, as desalination, in many parts of the world, is the predominant – and sometimes the only – reliable source of fresh, clean water to sustain thirsty populations and growing economies.

In conclusion, seawater desalination is truly a global industry. Through conferences like this week’s IDA World Congress and participation in organizations like the International Desalination Association, the desalting community is able to compare the lessons learned in disparate locations around the world where the technology is practiced. Through these networking opportunities and this exchange of data and information, it is more likely that it will be possible to establish environmental regulations and permitting procedures where they do not currently exist. Each new project adds to our understanding of the environmental impacts of seawater desalination and helps us understand how it can become new, local and sustainable part of our water supply portfolio.