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Pilot Perfect

Dec. 21, 2017 (revised Dec. 29) - Innovative water treatment technologies extensively tested before use

 

Bridge City recently underwent a 120-day pilot project to test the new system. The TCEQ is currently reviewing the data.
Bridge City recently underwent a 120-day pilot project to test the new system. The TCEQ is currently reviewing the data.
Bridge City utilizes a system designed by Filtronics out of California to remove excessive iron and manganese from the drinking water. Pictured is a 3,000-gallon tank of filter media, which the company dubs an Electromedia coagulation filtration system.
Bridge City utilizes a system designed by Filtronics out of California to remove excessive iron and manganese from the drinking water. Pictured is a 3,000-gallon tank of filter media, which the company dubs an Electromedia coagulation filtration system.

As the world around us becomes more developed, numerous pressures exert themselves on our water quality and water quantity. Old water sources might need better treatment, or other, more challenging water sources might have to be drawn from. Fortunately, exciting advancements are being made with water treatment technologies, and that’s good news for all of us.

Thanks to advances in such technologies as reverse osmosis, membranes, electrodialysis reversal, atmospheric water generators, ultraviolet light, ozone, and others, even with difficult circumstances, better water quality than ever before is possible.

But to the Texas Commission on Environmental Quality, promising new technologies can bring new challenges. In order to ensure each drinking water treatment plant works exactly as it needs to, the state of Texas requires proof.

When rules and regulations do not have established criteria for an innovative technology to follow, the TCEQ requires what’s called a pilot project.

Bridge City water treatment operators add chlorine in order to oxidize iron and manganese, which enables the filters to operate efficiently.
Bridge City water treatment operators add chlorine in order to oxidize iron and manganese, which enables the filters to operate efficiently.

“It’s how you prove to us that the technology is going to do what it needs to do to make the water quality that you want to make,” says David Williams, an engineer with the TCEQ’s Technical Review and Oversight Team for new drinking water facilities.

“Typically, there are technologies out there that we don’t have rules for,” he says. “When we don’t have a rule, a pathway for demonstrating a particular type of technology, there is the pilot study process that you can go through.”

A pilot process is essentially a scaled-down version of the water treatment facility that runs continuously for a period of anywhere from 30 days to as long as a year. Treated water is tested repeatedly as the pilot project is subjected to all of the variances the source water may experience.

The project will not clear testing until it demonstrates that the treated water protects public health. During this time, the water treatment process is adjusted and optimized, and additional steps may be required, depending on the results. And not to be minimized at all, the pilot project gives the water plant operator time to learn the finer points of the technology.

“Some technologies are evolving quickly enough that trying to put design criteria in rule would be problematic,” says Joel Klumpp, manager of the Plan and Technical Review Section in the Office of Water. “Because it takes a while to make changes to our rules, by the time we have something in here, the technology would have changed.”

That’s the case with low-pressure membranes, which numerous water systems in the state now use, Williams says. The materials used to make the membranes, which filter the water through microscopic holes—called pores—have been evolving. Improvements in the technology have improved durability and cost (for instance, see “New and Emerging Drinking Water Treatment Technologies” in Identifying Future Drinking Water Contaminants exit and Investigation of Low-Pressure Membrane Performance, Cleaning, and Economics Using a Techno-Economic Modeling Approach Adobe Acrobat PDF Document by the U.S. Department of the Interior).

Union Water Supply Corp. in Starr County, William says, is testing a membrane made out of ceramic, which should make it more resistant to tearing and, thus, improve the lifespan of the filters.

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Water Conditions Always Change

For the layperson, the water treatment process is a simple affair.

If you have a certain contaminant in the water, then the solution is to find the appropriate technology that can remove it, and presto, the situation is solved.

The problem, however, is that water chemistry is not a simple affair. Rather than a static target, water chemistry is as fluid as water itself.

Say that you want to remove a naturally occurring mineral deemed problematic. You find the technology that you need to do the job, but instead of just removing the mineral, it alters the chemical balance of the water, creating other issues, such as disinfectant byproducts or the water becoming more corrosive.

Corrosive water can interact with water pipes, leaching whatever they are made of into the water. This was one of the culprits in the Flint, Mich., water crisis.

When studying corrosivity problems in a distribution system, utilities may have to deal with a distribution system made of multiple types of materials, such as concrete, iron, PVC, or even wood pipe (very rare).

And because water can react differently with each of these materials, they can, potentially, have an impact on water quality and might have to be considered when adjusting the type of treatment technology used.

The TCEQ has a robust process in place to ensure that potential corrosivity is evaluated when any new source or treatment is approved. Also, under the Lead and Copper Rule, water systems must conduct regular compliance monitoring to evaluate corrosivity.

Due to the complexity of water chemistry, addressing one issue may require a water system to make additional adjustments before the water can be delivered to customers.

But will making those necessary adjustments complicate the water in some other way? That is what pilot projects can determine before a lot of money is spent on a solution that may or may not be ideal for that location.

In Bridge City, the water system was dealing with rusty or dark-colored water because of the secondary contaminants, iron and manganese. To fix that issue, the city turned to a company with a special filtration system, which oxidizes iron and manganese, allowing them to be removed by the filters.

A recent pilot project is being reviewed by the TCEQ to make sure it is functioning as it needs to.

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Finding the Right Mix

The pilot project for the city of Wolfforth tested out an electrodialysis reversal (desalination process) water treatment system, which uses electricity in order to facilitate the removal of ionized particles, such as fluoride, arsenic, alpha emitting radionuclides, and salts.
The pilot project for the city of Wolfforth tested out an electrodialysis reversal (desalination process) water treatment system, which uses electricity in order to facilitate the removal of ionized particles, such as fluoride, arsenic, alpha emitting radionuclides, and salts.

The right technology for a particular situation is not just about addressing what’s in the water. Williams notes that multiple factors come into play, including a community’s available funds, the ability to dispose of the waste from the treatment process, and available energy.

Cost may be the reason why regional water treatment systems are formed. The pooling of resources for expensive treatment processes, such as green sand filters for arsenic, help make these processes more affordable.

In some cases, a single emerging technology can address multiple contaminants cheaper than a system that would otherwise have to use multiple conventional processes to do the same.

In the case of Wolfforth, that city had to deal with dissolved salts, including sulfates and chlorides, alpha emitting radionuclides, fluoride, and arsenic, Williams says.

All of these contaminants are dissolved ionized particles, which is what the innovative technology called electrodialysis reversal is capable of handling. It does so by using a current of electricity to remove ionized particles from the water stream.

Data from Wolfforth’s pilot project not only affirmed electrodialysis reversal was the right technology for Wolfforth, but the pilot project data was also used by another community to get its electrodialysis reversal project approved by the TCEQ.

In the case of the desalination process, a big concern is what to do with the leftover waste.

In El Paso, where water is scarce, each drop is precious. They have had a reverse osmosis treatment plant to treat brackish water for years; however, they wanted to recover even more water, instead of returning it back to nature.

They recently completed a pilot project of a proprietary treatment system to extract more salt-free water.

“We are aware they want to protect their design,” Williams says of the company providing the technology to El Paso; however, “the TCEQ must evaluate the proposed treatment process.”

He says the TCEQ needs to know everything that comes into contact or interacts with the water to verify public health is going to be protected.

El Paso has a company interested in using the byproduct, salt, to sell for other purposes, so the waste resulting from the treatment process has been reduced as much as it can be.

Williams says there will always be a need for pilot projects because, just like water, the technology used to treat it is constantly changing—and also improving.

“There are always going to be new technologies coming along,” Williams says.

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All photos TCEQ.