Without doubt, oceans and seas are the largest waterbodies naturally occurring on the Earth. They are so huge and widespread across the surface of the globe that it appears blue from the space. As per many authentic references, about 97 percent of the water in the world belongs to these saline water reservoirs, whereas 3 percent is freshwater available as glaciers, ice caps, and waterbodies. Practically, only a portion of this freshwater is accessible for human use and consumption. While we strive to manage available lakes, rivers, and other inland water resources to meet present and future public needs, why not look to oceans and seas as potential alternatives for sustainability?
The water industry has already begun efforts towards converting naturally occurring saltwater into freshwater for community use. There are many success stories to list from different countries and several projects are presently in planning and development stages. Certainly, considering the vast opportunities that desalinated water can offer towards alleviating grave environmental issues, a major revolution for exploring seawater use is a must. Special initiatives by governments and environmental institutions will be the key at regional and national levels in this direction.
As such, any form of natural water resource used for public usage needs prior treatment. Degree and extent of purification depends upon the intake quality and its intended purpose. Ocean and sea waters differ from freshwater due to high concentrations of salts and minerals, thus requiring desalination to convert the high-density, saline water into a usable form. Various thermal and membrane technologies (such as flash distillation, reverse osmosis, electrodialysis, and many others) have gained significant attention in recent times.
On commercial levels, higher saltwater treatment costs are still a challenge in comparison to freshwater systems. Newer technologies and methods for desalination are evolving fast and economics will play a major role in determining future use of ocean or sea water by communities. Recovery of salts and minerals from ocean water can provide added benefits to offset the processing costs. Oceans provide geographical advantages for coastal areas and hence can be the priority and immediate areas of focus. However, to make the most out of this important resource, technologies will have to be advanced so that desalinated water could reach interior lands away from coasts at a reasonable and competitive price. These water prices would need to account for treatment, transportation, pumping, storage, and conditioning costs. Economic treatment and efficient transportation of treated saltwater can minimize a community’s reliance on rainwater and replenishing of freshwater systems. Reduced burden on freshwater resources will help to better distribute water towards agricultural, industrial, and public sectors.
Apart from treatment needs and processing costs, ocean water may provide some valuable benefits. While construction of new treatment plants using river or lake freshwater within cities or towns might face challenges such as land availability, site accessibility, intake locations, public resistance, industrial or domestic pollution, and other factors, oceans can provide greater flexibility for installing new water treatment plants when using saline water as the primary supply source. Secondly, unlike inland waterbodies, most of the oceans and seas across the globe are hydraulically connected with each other, thus making them most suitable candidates to avoid vulnerability associated with drying up of reservoirs or dependency on rainfall for refilling water storage. Considering the uneven distribution of inland freshwater, accompanied by water scarcity and floods, successful use of saltwater can be a golden opportunity for areas that are already experiencing water issues and affected by changing weather patterns.
Indeed, use of freshwater bodies for human activities are a better and more economical option to date; however, realizing the gravity of upcoming water problems, communities will have to eventually rely on oceans and seas for satisfying their needs. To solve sustainability issues on a long-term basis at international levels, ocean water is bound to gain significant importance. So, as communities continue to innovate water conservation and utilization techniques for freshwater resources, let’s explore the possibilities of tapping into the largest of water reservoirs. The possibilities are unlimited, and such opportunities cannot be ignored or underestimated.
Archis Ambulkar is an internationally acclaimed water expert and author of the well-received book “Guidance for Professional Development in Drinking Water and Wastewater Industry”, published by the International Water Association (U.K.). He has made vital contributions towards Oxford University’s Research Encyclopedia on the topic “Nutrient Pollution and Wastewater Treatment Systems” and Britannica Encyclopedia for its "Water Purification" and "Wastewater Treatment" sections. Mr. Ambulkar has written numerous international publications and participated with United Nations programs.