Appreciating the middle ages

The Environmental lab never looked so colorful and full of laughs and energy as it did on Wed, Aug 3, 2016. ms1Fourteen middle schoolers, participating in NU’s Girls Inventors Camp spent the morning with me learning to build water filters. They came from a few different towns near Northfield and scaled from sixth through ninth grades. Their personalities were just as diverse as the many physical, chemical, and biological characteristics of water that we discussed.

ms2With a limited amount of gravel, sand, activated carbon, and geotextile fabric, their challenge was to design and build a filter to treat some “gross”, “yucky”, “stinky”, “swamp water” (tap water with some garden soil, leaves and twigs, with a tiny drop of red food coloring) to almost clear quality, at a flow rate of about 0.56 ml/s (they had to collect 100 ml of filtered water in three minutes or less). ms4To do this, they had to first develop their concept sketches. These turned out so colorful, with appropriate headings, legend, and everything labeled using the correct terminology! ms3They then decided on the amount of media they would use in the order these design depicted, put on some gloves and got building. Every team met the flow rate challenge, but almost everyone had a pink tinge still left over in their filtered water. They knew that activated carbon was the primary component that could fix this color issue, so…

Every team had the opportunity to re-design their filters.ms5



They had to develop a new concept sketch, and note what changes were made and why. These second filtered samples turned out less pink than the previous, but now there was a serious commitment to get the color out. There were several creative solutions that emerged. Run the filtered water through the filter 13 ms8times, repeat layers of activated carbon in the filter, leave the filtered water in a separate beaker of activated carbon for a while, fill the entire filter casing with as much media as possible, so even though flow rate suffered in some cases, the final effluent looked ms7a LOT less pink – almost clear!

We had a lot of discussions along the way – the challenges of today, how they are already changing the world now, and how they will in 10 years, where does our water come from, why should we care, what do engineers do…We talked about using the right terminology to explain our work, learnt that it is ok to be nervous when presenting in front of an audience, and practiced our power poses.

Finally, we built a crude sand and gravel filter in a plastic cup and walked with these and a water sampler down to the Dog River across the rugby field on campus, stood on the bridge, watched fish swim by, collected some water, ran it through our make shift filters and walked back. The sun was hot, everyone was hungry and sweaty, but in my books – it was a morning well spent. I hope the girls felt the same way. I hope I see some of them in my classroom one day…

Photo credit: Mark Collier, Norwich Photography



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