Howard, Alexander (School: Timberline High School)
This project’s goals were to determine the failure point of carbon-coated oyster shells when filtering lead (Pb) from water, and to investigate which components of carbon-coated shells lend to the material’s filtration ability. Water containing Pb above 100 ppb was filtered through 5 g of carbon-coated shells. The filter outflow was periodically sampled and analyzed by an Inductively Coupled Plasma-Mass Spectrometer to determine its Pb concentration. Failure was defined as the outflow measuring above 5 ppb. Secondly, carbon-coated oyster shells, fired oyster shells, carbon, and non-fired oyster shells were used to filter water containing lead (Pb), cadmium (Cd), zinc (Zn), and copper (Cu). The outflow from each filter was sampled and analyzed by an ICP-MS. Firstly, the filter failed after ~4,860 mL of Pb-contaminated water. The filter’s output deviated by 0.19 ppb Pb and consistently filtered below 1 ppb Pb until the 4,000 mL mark, after which the output climbed to 5 ppb. In the second half, each filter was compared to the others using a one-way ANOVA, with a Tukey post hoc test to determine which filters were comparable to the others. These comparisons showed both carbon and fired shells provide carbon-coated shells their filtration ability. These results indicate that if 75 g of carbon-coated shells were used in a filter, its performance would be comparable to many activated charcoal filters. Oyster shells currently cost 0.44 USD per kg, and white sugar currently costs 1.17 USD per kg. 75 g of filtration material could be made for only 0.05 USD. Thus, carbon-coated shells are a promising option for developing areas where available filtration methods inadequately remove heavy metals like Pb or Cd from the water supply, while doing so in an inexpensive manner.
Fourth Award of $500