Dow Water provides sustainable water treatment in Gran Canaria

The Maspalomas-l desalination plant in Gran Canaria is seeing increased demand.
The Maspalomas-l desalination plant in Gran Canaria is seeing increased demand.
The DOW IntegraPac ultrafiltration modules.
The DOW IntegraPac ultrafiltration modules.
The DOW FILMTEC reverse osmosis elements.
The DOW FILMTEC reverse osmosis elements.

In an increasingly water-scarce world, there's a growing need for sustainable water treatments for business development. One of the most significant challenges is the water-energy nexus with seawater desalination one of the most energy intensive. This article looks at Spain's largest integrated, pressurized ultrafiltration and reverse osmosis municipal water plant, Maspalomas-I in Gran Canaria.

Bordered by seawater on all sides and experiencing low levels of annual rainfall, fresh water is a scarce resource on the Spanish island of Gran Canaria.

The Maspalomas-l plant

The Maspalomas-l desalination plant was built in 1986 as a solution to growing water scarcity issues generated by increased demand from tourism and agraicultural activities. In order to meet the needs of the local and tourist populations, the historically dry island has established desalination plants to support the production of potable water.

With over 12 million visitors per year, the island's local water demand has been steadily rising which meant that Maspalomas-l needed to extend its water processing capacity. After raising the water capacity, the plant's seawater intake system did not have the capability to provide the required feedwater flow to accomodate the plant's expansion and so a new open intake had to be constructed,

Originally the plant featured electrodialysis reversal technologies that were replaced by Dow reverse osmosis membranes in 2006. With a reverse osmosis capacity of 14,500m3of water per day, the plant extended its capacity with the addition of the ultrafiltration system in 2013, which treats 33,500m3 of water per day.

Utrafiltration solution

A two-stage pressurized filtration system was investigated as a conventional pretreatment for the new open intake. Conventional sand filters were considered but they did not meet footprint constraints, showed lower recovery and robustness for variable feeds, and resulted in higher civil works costs associated with the construction and installation.

Dow Water & Process Solutions, specialists in sustainable separation and purification technology, offered the IntegraPac ultrafiltration solution, capable of producing 32,000 m3/day and this was chosen for the plant, facilitating higher productivity and a lower lifecycle cost.

IntegraPac ultrafiltration technology streamlines design and installation, resulting in lower skid costs, reduced engineering design costs, easy assembly, a smaller footprint, and shortened lead times. The system's easy assembly and installation was a critical component for Maspalomas-I in order to reduce local civil works costs. Dow ultrafiltration technology is based on a technically advanced PVDF hollow fiber with uniform pore size that maintains high performance under a wide range of feed water conditions. Furthermore, its outside-in fibre technology facilitates higher solids loading, higher flow area, and easy cleaning.

The ultrafiltration system installed in Maspalomas I features the DOW IntegraPac IP-77 modules that are able to generate a recovery of up to 97% and are very efficient for the removal of colloids, particles, and bacteria. One of the characteristics of the IntegraPac elements that makes them particularly suitable for this system, is that they are chlorine tolerant, which increases the effectiveness of the cleaning and, due to the strength and fouling resistance offered by its PVDF fibers, the modules show significantly improved long-term performance.

The reverse osmosis installation features the DOW FILMTEC SW30XHR-440i and its membranes. These technologies are designed to offer a high flux that reduces the energy used while increasing salt and boron rejection for high quality water production. The DOW FILMTEC is also designed to decrease the energy expenses, which in a desalination installation can be as high as 50% of the plant's system energy costs.

Three years later

The site, operated by Elmasa Tecnología del Agua, upgraded its conventional sand filter pretreatments to its existing reverse osmosis installation. Since April 2013, the ultrafiltration system has been operating as pre-treatment for DOW FILMTEC reverse osmosis membranes, demonstrating strong and reliable performance with a consistent filtrate water quality and excellent fibre integrity.

After three years in full operation, Dow Water & Process Solutions' installation in Maspalomas-I, has proved that ultrafiltration is one of the most efficient pre-treatments for reverse osmosis systems in seawater desalination processes. The plant has seen both its efficiency and sustainability increase considerably following the installation of the Dow ultrafiltration pretreatment, even generating economic savings in the installation.

Water as part of the business agenda

Although water is one of the planet's most precious elements, its importance for business success is often undervalued. In fact, water has the potential to change the business landscape worldwide, especially in countries with high water scarcity, including Spain.

With this in mind, Dow Water & Process Solutions is exploring the growing importance of water to business development in an increasingly water-scarce world. Many businesses are already starting to recognize the intrinsic value of water beyond its monetary price. According to research from Global Water Intelligence, which appeared in the UK's Financial Times, companies have spent over $84 billion worldwide between 2011 and 2014 to improve water management. In addition, since 2016, companies worldwide are thought to be facing $14 billion of water-related impact from droughts and flooding and increased water stress.

Whether in water conservation policies or investments in monitoring and management, water is quickly rising further and further up the business agenda. In addition, businesses that have already introduced strategies to improve water efficiency are reporting reduced costs of up to 40%.

The water-energy nexus

One of the most significant challenges affecting water scarcity is the water-energy nexus, the intrinsic relationship between water and energy, in which one is necessary to produce the other, and vice versa. This relationship will only become more strained as the world's population continues to increase. The United Nations estimates that by 2030 the world will require 30% more water, 45% more energy and 50% more food, as the global population is expected to exceed 9.5 billion by 2050. If not managed efficiently and in a way that optimizes the production of water, energy and food, a stable supply could be threatened.

Both water and energy are necessary for a productive, healthy society but neither can exist without the other. In fact, energy is the costliest element of seawater desalination, one of the most important water treatment processes for the municipal sector. The energy required in seawater desalinization can range from about three to six kilowatt hours (kWh) of energy to produce one cubic meter of potable water, making it one of the most energy-intensive, and therefore one of the most cost-intensive, water treatment processes available. Knowing this can help us to understand how efficient management in one area can also improve the sustainability of the other. If this relationship is managed efficiently, industrial competitiveness can be increased.

More sustainable technologies

The ultrafiltration treatment installed has allowed the Maspalomas-I plant not only to supply the area with high quality water, but its compactness has helped to reduce the site's footprint by 40%, compared with conventional treatment methods such as sand filtration systems. This compactness is especially important in remote locations such as the Canary Islands where accessibility is not always easy. Additional benefits of the ultrafiltration pre-treatment system include a higher capability of the membrane to cope with variable feed water quality and tidal changes, especially for an open intake, as well as better and more consistent filtrate water quality. Overall, ultrafiltration represents a competitive advantage over other treatments, helping manufacturers' efficiency and increasing their economic savings.

A glocal look to the future of water

In order to continue to provide enough water, without exacerbating water scarcity, investments in alternative water sources or improved water treatment systems in the industry are necessary. Dow Water & Process Solutions continues to spearhead the development of sustainable technologies that reduce chemical use, cost and energy requirements when treating water.

Meeting the emerging needs of the water-energy nexus can be done by making water filtration and purification technologies more effective and energy efficient. Companies should also take into account that they cannot advance a circular economy through technology alone. With increasing demands placed on limited freshwater resources, they must move beyond a linear economy model where they throw out raw materials after using them, towards a circular approach in which raw materials are reused and therefore costs reduced. Alliances and partnerships with entities beyond their direct value chain are also critical to making the pivotal transition to better-managed water resources.