Making Drops to Drink

By Hank Hogan | November 2, 2015

The sailor in the 18th century poem “Rime of the Ancient Mariner” got it right when he said, “Water, water, everywhere, nor any drop to drink.” When surrounded by seawater, you’re fresh out of luck if you’re thirsty. However, that situation may be changing, thanks to desalination projects that turn salt water into fresh water.

A case in point comes from a plant soon to be completed in Carlsbad, Calif., located at the northern end of San Diego County. Owned and developed by Poseidon Water, the plant will provide clean water to approximately 300,000 people, and FRP composite piping plays a key role because of its material properties. “For large diameter, above ground, low-pressure piping, IDE finds composite piping to be the most suitable,” says Ziv Shor, project manager for IDE Technologies.

Based in Kadima, Israel, IDE Technologies specializes in the development, engineering, construction and operation of enhanced desalination and industrial water treatment plants. The company built the largest desalination plant in China and also built and operates the largest desalination plant in the world, which is located in Israel. IDE is the process designer and equipment supplier for the Carlsbad Desalination Plant and will operate it.

For California, the development of additional water supplies is critical, which is why the Carlsbad Desalination Plant is important. The state is facing one of the most severe droughts on record, resulting in a government edict for a 25 percent reduction in water usage state wide. Being able to economically transform previously undrinkable seawater into useful drinking water could be part of the long-term solution to the crisis.

Shor says the Carlsbad facility is a game changer. It’s the largest desalination plant in the Americas and is the first major California infrastructure project with a net zero carbon footprint. The plant’s design is based upon IDE’s reverse osmosis technology. In reverse osmosis, unwanted contaminants, like salt, are removed by forcing water through a semipermeable membrane. On one side of the membrane you get drinking water. On the other, you get an effluent with a higher concentration of brine, making it corrosive. In the Carlsbad plant, IDE used what it calls an innovative pre-treatment phase to improve efficiency and reduce energy consumption.

Up to 108 million gallons a day of salt water will go in for treatment, with an average of 50 million gallons of high-quality drinking water coming out. That water travels through 10 miles of pipeline, so it’s an important component for the success of the entire project. For some of the piping, GFRP composites were selected over alternatives like high-density polyethylene (HDPE) due to the former’s greater strength and smaller longitudinal expansion, Shor says.

Ershigs of Bellingham, Wash., designed and manufactured the above ground GFRP piping. “FRP is widely used and proven in desalination globally,” says Steve Guay, general manager of the Ershigs facility that built the piping. “The value proposition is internal and external corrosion resistance in a sea water and seaside environment.”

The Carlsbad piping ranges from four to 72 inches in internal diameter. Ershigs produced 1.3 miles of piping, with a total weight of half a million pounds. It took the company from late 2013 to early 2015 to design, manufacture and deliver the piping to the project. Most of that time was spent manufacturing via filament winding.

Ershigs used Reichhold’s DION® 9102 series of bisphenol-epoxy vinyl ester resins for a corrosion barrier, with Ashland’s HETRON® 922 epoxy vinyl ester resin in the structural layers. For structural reinforcement, the company used Owens Corning C-glass veil, chopped strand E-glass mat and E-glass woven rovings.

Ershigs faced some challenges producing and delivering the piping. The project’s construction schedule, for instance, was demanding and required some ingenuity to meet. Complying with the NSF-61 drinking water sanitation standard meant that the assembled fiberglass spools had to undergo a heated post cure. That took time and could have impacted the project schedule.

To deal with that, Ershigs’ metal division fabricated two custom roll-in racking systems, says Guay, “which allowed us to stack multiple spools into our post cure oven, thereby maximizing usage of the available cubic feet of the oven and minimizing the FRP spool handling and ultimately any potential delivery schedule impacts from the post cure activity.”

In meeting the schedule, it helped that Ershigs has its own specialty construction division, says Julie Delaney, project manager. The experience gained in supporting that division made it easier to address the Carlsbad project priorities, sequencing and coordination. In the end, 91 truckloads of piping rolled from Ershigs’ manufacturing plant in Bellingham to the jobsite in Carlsbad.

“Although this important project was high profile, completion of Ershigs’ scope was fairly straightforward,” says Delaney.

While composites are used extensively in the Carlsbad project, Shor says they could play an even bigger role in future desalination plants. For instance, stainless steel alloys containing chrome and molybdenum for corrosion resistance are currently used for the high-pressure piping through which the corrosive effluent travels. The pressure in the piping reaches roughly 1200 psi, meaning that a composite pipe would currently have to be unacceptably thick to be used. However, Shor notes that ongoing research and development efforts could change the cost calculations that today favor stainless steel over composites.

“We believe that such [composites] technology will eventually be a common standard for high-pressure corrosive effluent in the coming years,” Shor says. Such advances could further improve the cost effectiveness of desalination. With the success of such projects, landlubbers and mariners, ancient or otherwise, will finally have something to drink.

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