My last week in El Paso was a bit hectic to say the least. Interestingly enough, the CDI was creating a more salinated solution rather than the expected desalination, and the system wasn’t getting anywhere near to producing drinkable water. First, we tried rinsing the electrodes for an extended period of time in case of super saturation, which appeared to work at first, but the electrodes still wouldn’t remove a sufficient amount of ions or dump them quickly enough. Then, we switched the carbon electrodes with a new set just in case we were nearing the end of the electrodes’ lifespan, but the result was more or less the same. Next, we tried both increasing and decreasing the concentration of the feed salt solution, trying to make the conductivity peaks more distinct, but that also didn’t seem to have much effect. At the suggestion of Dr. Walker, we tried to test the system for the presence of a short circuit, which could explain the electrode’s lack of absorption; however, this proved to be much more difficult than expected because of the presence of water in the system. Before leaving on Friday, we tried to use air to push any remaining water out of the system in order to accurately test for a short circuit, but we couldn’t be sure that the system was completely dry. All we knew was that when a meter was connected, it indicated that our system was short circuiting.

On Thursday, I took a mini-road trip with a two other interns in the lab up the Rio Grande River, collecting water samples for one of the intern’s summer project. I’d only ever seen the Rio Grande down by the most southern tip of Texas, so it was interesting to travel to New Mexico and see how different it was. We went up to Elephant Butte and then made our way back down to El Paso, stopping about 13 times at different points of the river, some of which were not as accessible as others..

It was definitely tough leaving on such an indefinite note, even more so because it felt as if our project had just begun. I’m sure that I’ll keep in touch with Seye over the next couple of months and I’m excited to hear about his progress in the system’s automation and his growth in understanding about capacitive deionization in general, but I’m sad that I cannot fully accompany him on that journey. I never could have imagined that El Paso would be so dear to me at the end of this internship. Saying goodbye was difficult, but I know that just means that I was lucky enough to have a meaningful experience in which I had the opportunity to meet a whole group of wonderful, intelligent people that give me a reason to come back one day.

After much blood, sweat, and tears, I’m proud to announce that we finally fully set up the CDI system (of course, it leaked the first time we ran water through it, which took a couple tries to figure out). We ran about 1 volt through the system and successfully reduced the conductivity for about 5 minutes, at which point we assumed that the electrode became saturated and could no longer desalinate the solution. Then we reversed the polarity of the carbon electrodes to dump the collected ions into a concentrate stream, which took a while most likely due to the significant amount of collected ions. We are still trying to figure out the quirks of the system, but the future looks promising; however, it’s all a bit bittersweet, since the project feels like it’s just beginning.

On another note, LabVIEW coding has not been going so well. After extensively reading different manuals and trying my best to figure out the new language, I discovered that the program is relatively easy to use and navigate…if it’s set up correctly. Focus had been shifted mainly toward acquiring materials to complete the CDI system, so once I could direct my attention more fully to learning the software, I quickly ran into quite a few problems while actually trying to write a code connecting different instruments to the computer. Fortunately, Dr. Walker was able to clear most everything up once back from his trip delivering water filters to those in need in Ecuador. However, we ultimately discovered that the LabVIEW software would not measure data due to an installation error, which we are currently still trying to figure out so that we can finally get the ball rolling on this automation.

As my time here comes to an end, I can’t help but feel saddened by the eventual goodbye to this wonderful place and the people that have truly made this entire experience worthwhile.

We were a bit stuck last week in terms of finding a suitable current collector to use with our electrodes, so we reached out to Dr. Tom Davis, who we knew had extensive experience with electrodialysis systems and could most likely provide a few helpful tips. From our research, we knew that a titanium plate would serve as the best current collector, but faced the challenged of finding one that met our stack dimensions and could be delivered in a reasonable time frame. With Dr. Davis’s help, we stumbled upon an El Paso metal company that had a single titanium plate just big enough to be cut to fit our stack. Just needing a way to connect the power supply to the current collector, we went to several places looking for titanium screws to avoid unnecessary corrosion between the metals, but they’re apparently pretty uncommon. Fortunately, we found a company in Nevada that could deliver the screws by Wednesday of this week, so once those arrive all that’s left is to weld the screws to the plates and then we can start testing the system. Cheers to progress

Another week has passed and we still haven’t run any real tests on the CDI. All of the electrodes finally arrived, but we now face the challenge of connecting them to the power supply. We might have to purchase titanium plates but I’d like to find another conductive, non-corrosive material we don’t have to order and wait for. The creative juices are definitely flowing freely with this project, that’s for sure. Also, a new power supply should arrive soon that will allow us to automize the system, which will be an interesting challenge since I have no experience with labview. Hopefully, all goes well. Honestly, it is a bit frustrating not being able to run the system and I think we underestimated the amount of time acquiring all of the materials would take, but I’m remaining optimistic.

We had some time to mess with the CDI setup this week, so we cut out a new rubber gasket to place between the two plates and sealed the stack up without the electrode. Then we connected the stack to the filter system with new tubing and ran water through it to see if we had any leaks while also measuring the differential pressure flowing through the stack and whether the system’s flow rate was accurate.

Also, we finally placed an order for the carbon electrodes. Seems like forever since we began looking for them and we still weren’t able to find a company willing to sell us a larger electrode. Thankfully, the small company that we bought the thinner electrodes from suggested a couple of other contacts that might be able to help us out, one contact being a professor at Case Western University that might already have electrodes that meet our specifications. So, we contacted him and he responded not even 3 hours later, saying that he had 8 electrodes that met our specifications and could send them that same day, no charge. What luck, eh? Anyway, our week ended on a high note and all the electrodes should be here by Tuesday 🙂

P.S. Here’s another beautiful pic of El Paso:

This past week was a bit slower than last. Neither me nor my partner have any experience with capacitive deionization techniques, so a majority of the week was spent reviewing capacitive deionization research. The lab has already done research with electrodialysis and there is a previously used electrodialysis system already in place, so we really just need to modify it to include carbon electrodes. Easy enough right? Not necessarily. Since we’re reusing a pre-existing stack, it requires a specific size of electrode in order to operate optimally. However, we’ve only been able to find about 3 distributors of carbon electrodes and none so far have been able to meet our specifications. So we’ll have to either figure out how to modify our stack or continue looking for an electrode distributor that can meet our specifications.

This weekend my lab group planned a trip to Carlsbad Caverns, which was pretty amazing. I knew it was something I wanted to do before arriving and was already disappointed when I realized how far it actually was from El Paso, since I don’t have a car here. Fortunately, everything worked out in my favor and we all had a great time.

I also went for a short hike with the other UTEP intern, Alex, at Billy Rogers Arroyo. It didn’t seem particularly well kept, but it was a fun experience all the same. About halfway down the trail, I stepped on a thorn, which went straight through my shoe and into my foot. It took about 5 minutes for me to work up the courage to pull it out (during which Alex captured that wonderful picture below).

Cheers to new friends and experiences.

My experience in El Paso has been pretty great so far and UTEP has a beautiful campus, whose sand colored buildings along with the dry, hot sun never let you forget that you’re in the desert. I met Dr. Walker’s research group as well as my mentor for the summer, Seye, Monday morning and immediately began my training on different types of water analyses. Seye had some water samples from the desalination plant that he had to test, so we used that as an opportunity train me. Throughout the week, I learned how to measure alkalinity and total dissolved solids, test for silica, and use the Ion Chromatography machine. I’m happy to report that everyone is very friendly here.

On Thursday, I got to help disassemble a solar powered water desalination system located at the Kay Bailey Hutchinson desalination plant, which is the world’s largest inland desalination facility producing 27.5 million gallons per day. We arrived at the desalination plant around 7:30am to beat the sun, but it was tough work and the disassembly took longer than expected. I appreciated the experience because it gave me an opportunity to see the world’s largest inland desalination facility in action as well as see the setup of a solar powered desalination system that will be used to produce water suitable for human consumption or irrigation in Honduras this summer. By the way, I cannot carry a cinder block by myself and the El Paso heat should not be underestimated.

This weekend I made it downtown and stumbled upon a free music show with a band called Sangre Gitana. It was an enjoyable experience and I felt fully immersed in El Paso’s culture for the first time as I watched people dance and enjoy themselves with their family and friends on a typical Friday night. I also stumbled across San Jacinto Plaza, which seemed to be located at the heart of downtown El Paso. There was a fountain at the center of this plaza with a statue depicting several alligators climbing one another. A man passing by informed me that the fountain used to be a pond that held real alligators, which I found hard to believe of course, but turns out he wasn’t kidding! Apparently, the pond was permanently removed after 1974 for the alligators’ safety and today, the sculpture honors the original alligators that were once a staple of El Paso culture.

It’s been a relief to be back home after such a long and stressful semester. You never do realize how fast a month can fly by until it’s the night before your 9am flight to El Paso and you’re struggling to fit 7 weeks of life into two suitcases. (I guess I don’t really need that huge blanket, but I’m sure going to try and make it fit)

Of course, traveling to a new place is always exciting. There is so much potential, so much knowledge to be gained, so many new experiences awaiting me. It’s interesting to think how much of this internship experience will be completely new to me. This will be the first time traveling completely alone and to a place without family or friends to make it feel at least a little bit like home. It sounds a bit daunting, but I’m up for the challenge of putting myself out there and meeting new people. I have absolutely no experience with capacitive deionization systems and to be totally honest, I first heard about the concept a couple of weeks ago, but that’s just another challenge I’m sure will be fun to explore (and eventually overcome). I’m grateful for this opportunity to branch out and gain more independence as well as experience in the field of water treatment. I couldn’t think of a better way to spend my summer. Cheers to broadening horizons and I look forward to sharing more updates on my research and desert experience.