Stefanie Tompkins

Transcript

Tzahi Cath:

Everything is fascinating in water and wastewater. And wastewater even more because it’s more challenging. And every water is a new challenge and water is not stagnant. Water changes all the time. And so when you design something, you need to have enough flexibility in the process to address removal of different contaminants at different concentrations at different times.

Tzahi Cath:

My name is Tzahi Cath and I’m a professor in the Department of Civil and Environmental Engineering at the Colorado School of Mines.

The Conveyor:

You’re listening to The Conveyor, the podcast that brings you the latest research, new discoveries and world-changing ideas from Colorado School of Mines.

The Conveyor:

Tzahi, your work in direct potable reuse or DPR is a newer approach to clean water. What’s the significance of DPR in relation to other techniques?

Tzahi Cath:

Okay. So for that, I need to take one step back because there are different types of water reuse. I think the one that most people are really familiar with is the non-potable reuse. This is cleaning wastewater. And then sending them back to the environment, either discharging it to a river or reservoir. That’s what’s been done for many, many years. And then slowly, people started cleaning the water to slightly higher quality. And then using them for irrigation, for example, or for cooling towers, so that’s the non-potable reuse.

Tzahi Cath:

Then we started with potable reuse. That means we can treat the water to even higher quality and use it for drinking. And that’s where direct potable use and indirect potable reuse come to play is taking the water, treating them to very high quality, blending them back into the environment, through what we call environmental buffer and can be back into the groundwater or surface water, let them mix with natural water and then pulling them back, treating them in a water treatment plant, and then putting them back into the distribution system.

Tzahi Cath:

Indirect potable reuse, it’s what we call pipe to pipe. So we treat the wastewater, we send the treated wastewater to another advanced water treatment plants, treating the water, and then we might directly drink this water or blend them with other clean water in the distribution system when it goes to the customers.

The Conveyor:

So it’s a lot less steps than indirect potable reuse.

Tzahi Cath:

It’s less steps in there’s practically potential for less contamination. Because if we send the treated water and this is high-quality water, and we are doing it already in Colorado, that’s a chance that they will get contaminated again in the environment. So when we do pipe to pipe, there’s less interference. We don’t allow the water to get contaminated or touch other things again.

The Conveyor:

Okay. So it’s more streamlined and it adds a preventative component to cleaner water. So then why would a DPR system be beneficial for a state like Colorado? I mean, we’ve got good water, don’t we?

Tzahi Cath:

Yeah. And so in one way, we are very lucky that we are in a state that we have the Rocky Mountains that provide us a lot of water and this is great. But the Colorado situation is that majority of the water is on the west slopes and majority of the population is on the east slope. And so we have a lot of water transferred from the west slopes to the east, through different water conveyance systems, but it’s not enough. And when we will have the big drought … now, still, we manage. If we won’t have the infrastructure in place, we’ll be in trouble. We’re an inland state. We are not on the shore. We don’t have like Texas and Florida and California. We cannot tap the ocean to get water. And so where do we get water? Either it’s natural water that come from the sky, it’s groundwater and that’s it. So one of the option is here, we have water. Let’s reuse it again and again by treating the water to very high quality.

The Conveyor:

And where does your recent research project come in? I hear it’s on wheels.

Tzahi Cath:

Yeah. So we were involved three years ago in a project that was led by Denver Water. They demonstrated direct potable reuse. And then two years ago, it started again with the Colorado Springs Utilities that approached us and say, “Hey, we are going to do our demonstration and do you want to join us?” And, of course, we said, “There’s no chance that we’re missing this opportunity.” We said, “Yes,” immediately. And we continue brainstorming on how can we do it and how can we take the different outcomes from previous studies and make them better? And that’s when we started talking about, let’s put it in a mobile concept that … Yeah, we’ll do a small study for Colorado Springs Utilities and for the customers. But then we have a system that can move from one community to another, to demonstrate to other communities that that’s possible.

Tzahi Cath:

And we started working on that and we started talking and planning. And that’s the point where we decided to submit a proposal to the open call of the Colorado Water Conservation Board for funding. And so they gave us funding. I think, close to $350,000 to design and build the system. Colorado Springs Utilities hired Colorado engineers to help with the design of the system. And School of Mines took upon ourselves to build the trailer. So we bought a 35-foot long cargo trailer. Some of the systems that’s sitting inside, we bought them as a package. Other system, we built ourselves. And all the integration and the control system, the electrical and electronics and sensors, we all either built ourselves or install an integrated ourselves.

The Conveyor:

Wow. So this is a first of its kind.

Tzahi Cath:

I think what we heard from Colorado engineers that actually this is the only type of mobile DPR trailer in the world that they know of. And that’s going back a little bit into technical details and maybe it’s a segue into talking a little bit about the technologies.

The Conveyor:

Yes, please.

Tzahi Cath:

Most DPR systems use reverse osmosis as one of the main barriers to stop small contaminants. Our system doesn’t have reverse osmosis system. So it’s a non-desalination, non-reverse osmosis direct potable reuse, which is very unique. And it’s unique for very specific locations. So a trailer like that might not work for example, for Phoenix or other places in Arizona, maybe in New Mexico, where in addition to other contaminants in wastewater, you have a lot of salt in the water. The only way to remove salt, and again, it can be just regular sodium chloride but can be other different minerals. Most of the processes that we have in the trailer cannot remove them. You have to use some kind of desalination process like reverse osmosis or nanofiltration.

Tzahi Cath:

In Colorado and many other states, we are lucky that our impaired water doesn’t have much salt. So we don’t need to remove salt from the water. We can use our processes without desalination step in the middle. And just to note here that if you do have salt and it won’t impact any of the processes in our mobile lab, you can take the effluent or the clean water coming out of this trailer, feed it into reversal osmosis or nanofiltration and you produce clean and even better water at even lower costs because all the pre-treatment that you need usually before or ahead of desalination membranes is done in this trailer. So even the energy costs associated with desalination will be reduced if we use our trailer.

The Conveyor:

Looking towards the future, what sort of unique techniques or benefits other than clean water will come from this work, the bells and whistles, if you will?

Tzahi Cath:

We stuffed the trailer with a lot of technologies beyond the treatment technologies. Some of the things that we are really unique about is that we installed many water quality sensors there. So we purchased and installed three sets of networks that, in real time, collect a lot of data on what happened to the water along this train of processes. So we measure the simple things like temperatures of flows and pressure, but also concentration of ammonium nitrate, dissolved oxygen, pH, we have a particle counter, even UV spectrum.

Tzahi Cath:

A lot of things that we will use in separate projects, in what we call data science integration, to learn about the process and how we can improve the process, improve the efficiency of the process through analyzing the data that the process is generating. And then, we’ll have to see what’s the demand from communities for something like that. We know how to build it. We can build another one tomorrow, but it highly depends how it will be used. So many questions and great research projects and the sky’s the limit here.

Tzahi Cath:

To learn more about this project in Civil and Environmental Engineering at Mines, visit cee.mines.edu.

Tzahi Cath:

Thanks for listening to The Conveyor. To learn more about how Colorado School of Mines is solving some of the world’s biggest engineering and scientific challenges, visit mines.edu, and then join us back here for our next episode.

This episode of The Conveyor was produced by Ashley Spurgeon and was hosted and edited by Dannon Cox. 

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About the Podcast

The Conveyor brings listeners insights into the latest research, new discoveries and world-changing ideas from Colorado School of Mines.

The viewpoints and opinions expressed by featured guests do not necessarily represent those of Colorado School of Mines.