504: Dialysate Water Filter

Our goal was to reuse wasted water by creating a cleaning filter for spent dialysis water. This is important because water wasted in dialysis is greater than 50 percent. Dialysis mimics the way the kidneys filter blood within the body. A dialysis machine must use ultra-pure water to prevent infection. Our sponsor provided the goals and targets for this project. 

The filter attaches to dialysis machines in hospitals and treatment centers, cleaning enough water for dialysis to finish within 3 to 4 hours. We first run standard tap water through a reverse osmosis drinking water filter. Our custom filter then uses carbon nanotubes to remove unwanted particles from the wastewater to bring it up to “ultra-pure” quality. The filter membrane is a thin, black sheet made up of thousands of individual tubes which allow water molecules to pass through while the bigger molecules catch on to the membrane. The tap and wastewater move through this membrane to produce ultra-pure water. This clean water runs through the dialysis machine and the carbon nanotube filter again. To make sure the water is ultra-pure, it’s measured for remaining total dissolved solids with a digital water quality testing pen. Disposable water quality strips measure the samples for metals or other chemicals. We took water samples and tested at two places. They’re tested before and after the carbon nanotube filter to show if the water is clean. The total dissolved solids measurement meets the standards of ultra-pure water. The disposable strips results also met the ultra-pure water standards.