Team:Lethbridge Canada/Water Treatment


Lethbridge High School iGEM Team

Water Treatment

Waste Water Treatment Plant Visit

On June 13, 2014, members of our iGEM team visited Lethbridge’s local waste water treatment plant in order to get an idea of our project could be implemented into a waste water treatment plant. Before visiting the waste water treatment plant, we had envisioned our E-coli to be trapped in size 1,000 Dalton dialysis tubes that would only allow the media in which the cells are suspended in, cell debris from broken cells as well as our enzyme, beta-lactamase, to escape. We were planning on having another 1,000,000 Dalton dialysis tube included in our construct through which the media could diffuse through by continuously pumping fresh water into our construct. This would decrease the concentration of the media on the opposite side of the dialysis tube and thus allow for constant diffusion of the media. We wanted to eliminate the risk of genetically modified DNA finding its way into the water system by inserting filters similar to filters found in miniprep columns that would capture the DNA. This would enable only the enzymes to be excreted into the water system.

Water Treatment

The waste water treatment plant already uses bacteria found in a Human’s gut ecosystem for the cleaning process in order to eliminate nitrogen and phosphorus in the water. Excessive nitrogen/phosphorus in the water can stimulate algae growth, which results in a decrease of dissolved oxygen for other aquatic species. The bacteria in the cleaning process were first introduced into an anaerobic environment, which caused them to take up nitrogen/phosphorus. Next, they were put into an aerobic environment in which the nitrogen/phosphorus inside of their cells was excreted back out into the water. The last step of the process was to move the cells back to an anaerobic environment in which they would take up even more nitrogen/phosphorus than they previously had in their system. Through these steps, they cleaned up the water from excessive nitrogen/phosphorus. In addition to the bioreactor, the waste water treatment plant also used Ultraviolet radiation (UV light) to treat its water, as a final preventative measure. In this final step, UV light was shone underneath the stream of water that rushes out of the waste water treatment plant. The UV light degrades any DNA/proteins, including viruses, to ensure that no microorganisms can replicate the left-overs, after everything enters the water system. In addition, UV light is much safer and cheaper to implement than adding chemicals such as chlorine into the water to disinfect it.

Water Treatment

After having toured the waste water treatment plant, we now believe our initial complex construct is no longer necessary; however, instead we can implement our construct into a waste water treatment plant as a large bioreactor that contains our E-coli cells. Since the waste water treatment plant already uses bacteria in its cleaning process, there are enough nutrients in the waste water for our E-coli to survive and thus we do not need to include any LB media in our construct. In addition, adding our E-coli directly into the waste water system would no longer be an issue regarding the release of genetically modified organisms because the E-coli would be contained within the bioreactor and all additional DNA and proteins would be degraded under the UV light before the water is released into the environment. Being able to add our E-coli cells directly into the water also allows us to export beta-lactamase to E-coli's periplasmic space, rather than exporting beta-lactamase directly out of the cell. This means that only the E-coli cells (that contain our beta-lactamase) and the antibiotics would need to come in contact with eachother in order for our construct to start degrading antibiotics, instead of having to force the small beta-lactamase enzymes and antibiotics together. Water Treatment

Overall, the tour of Lethbridge's waste water treatment plant was very useful as it helped us to envision the industrial applications of our project.