Week Recap 6/26

What’s good y’all,

So, I got all kinds of news about this week. Monday, I spent all day in the lab making our NSF53 challenge water. In total, it took about 3 to 4 hours to complete. I took nano-pure water, which is basically DI water which has been filtered down even more. I spent most of the time

I’m adding salts.

mixing and adding a number of salts to water. I added acid to bring the pH down. Except, when I got to the second to last step, my mentor wanted to added the sodium hypochlorite (bleach) just because she is more experienced and wanted to show me. Well, she miscalculated the amount we would need to achieve desired concentration. She thought the concentration of the sodium hypochlorite was 4000mg/L. Actually,

The blue handle is the dispenser form the Nano-Pure water system. That’s the tank for the water. “NSF Water Making Station”

it was 40000mg/L. Which resulted in us adding 5mL to the entire 72L solution, rather than 0.5mL. A factor of 10 made the concentration of total free chlorine go from 3.02mg/L to the desired 0.79mg/L. That was annoying, so I had to scratch that water and start all over again. Doing everything right the second time around. I did all the mixing and adding this time. The best part, which is actually the worst part was

weighing of 92.16mg of Sodium Arsenate Heptahydrate. The amount was just a few little crystals. That little bit, made the entire water solution completely toxic, and that amazes me. That’s the last step, and

Challenge water recipe and fancy glass-door scales.

after doing it all a second time the water was ready to go. Tuesday, we began packing the columns with media and setting up our entire tests with source water, inffluent and effluent tubes, pumps, and proper flow rates. Well, when we got to the point of attaching the columns to rest of the setup, there was large amounts of back pressure in the system. The pumps began to knock and tick, which eventually changed the flow rate. After too much pressure built up, the tubing began to bust open and squirt water. Basically, after another 3 hours of setup, a failed setup was the result. The problem we’ve concluded, was that the media is too finely ground, being between 88 and 106 micrometers. It was so compressed in the column and pack tightly, that we it was resisting most of the water in-flow. Causing the pressure to build up, leading to explosions in our setup. We are still

Failed E-33 column

not sure, we tried grinding it again and packing it into new columns, which took more time once again. This was a different grinding setup though. Originally, the cryogrinder was used, but the second time I did something called wet grinding and wet sieving. I put some media into a ceramic mortar and added some DI water, then ground with a pestle. The media is always in water and

Mortar & Pestle, sieve stack, and container of raw E-33

never goes dry. I don’t know why this would make a difference in the column because it was sieved to the same size through the cryogrinder. I was in for a surprise with the task of grinding by hand. It takes forever to get the necessary amount out from the amount put in. I put a lot of E-33 in to grind and I don’t get very much out. It seems to me that some media dissolves into the water, and the rest is ground too fine. Which means it passes through the desired sieved size. That’s the only problem I had, it was just time consuming. The media was broken down to the same sizes, the method of grinding was just different. But, for some reason, it did make a difference. Once I packed the first column with E-33, I got our column size correct, there was no back-pressure, and the water was flowing perfectly fine. There was no problems with that system at all. Next week, after the holiday, I will begin grinding the Zimmermedia and repeat the process.

Hopefully all goes well next week!

-Chris