Arsenic Removal via Cattails

Mar 2, 2011 by jroot    No Comments    Posted under: All Projects, Classroom Projects

This Product, Design and Innovation (PDI) Studio 1 team of Caroline Pitner and Meghan Olson, students of Rensselaer Polytechnic Institute’s class of 2014, began their mission with an attraction to cattails while they were exploring various materials that could be applied to low-cost, “expandable” shoes. Captivated by the many potential applications of cattails, they decided to investigate the plant’s potential. They discovered that cattails have been referred to as “nature’s supermarket,” and found that this versatile plant treats arsenic as a nutrient. Simultaneously, they learned about the problem of arsenic-contaminated drinking water in India and Bangladesh, which is actually unrecognized by about 88% of those who are consuming levels well above the amount considered “safe” on a daily basis.The problem is that as organizations are funding the implementation of tube wells, they are propagating the problem of arsenic contamination, especially in areas like India and Bangladesh that are geographically prone to natural arsenic in the soil and rock (partially due to thawing snow from the Himalayan mountain range in the spring). Arsenic, a carcinogen, is known to cause cancer of the bladder, lung, skin, and kidney as well as other symptoms such as liver and spleen enlargement, myocardial degeneration and cardiac failure, and sensory- predominant peripheral neuropathy.Going full circle with an attraction to the beauty of the natural abilities of cattails and of the widespread and unsolved problem of arsenic contamination, this team has developed a vision of a living filter made of cattails which can be retrofitted to existing tube well reservoirs to cheaply and effectively remove arsenic from well water.The filter will be delivered in the form of biodegradable rice-husk mesh netting with a bamboo frame that allows the user to grow the cattails. Cattails are proven to be extremely versatile and can survive in many environments, especially the ones that need this system the most. Once the cattails have grown on the mesh netting/frame, the mesh will biodegrade and the cattails will thrive off of the water from the reservoir and will nourish themselves with their own waste, as they are a self-recycling plant. After purification, the water will be emptied into a separate reservoir, where the villagers can then collect the water for consumption at a water spout. Using a cattail purification system, the lives of the villagers can potentially be extended by thirty-five years.Design Approach & Next StepsThe next steps that this partnership is planning to make involve developing a comprehensive business model for installing and maintaining the cattail filters, including training a “village expert,” educating citizens, and creating a profitable industry for the users of the filter by developing a way to harvest the cattails and bio-accumulated arsenic.We can also potentially address the problem of arsenic contamination using bacteria instead of cattails. Recently, NASA discovered a bacterium in a lake called GFAJ-1 that can use arsenic in its molecular make-up instead of the phosphorus originally thought to be needed to fit the former nutritional requirement of terrestrial life. This discovery is opening up an entirely new field within microbiology. The fact that a living organism can subsist on consuming arsenic alone means there is great potential for bacteria, which are extremely reproducible and even lower- maintenance and more versatile than cattails, in water filtration.This discovery prompts an audacious but seemingly feasible vision: Imagine simply pouring a bucket of bacteria in, and, upon straining the bacteria out via a simple filter, being able to scoop up a jug of clean, arsenic- free water. Such a method would be more convenient than our cattail filter and much healthier and less expensive than the existing chemical filtration systems.Project ContactCaroline R. PitnerMechanical Engineering and Design, Innovation, and Society