Combination of Co-Precipitation with Zeolite Filtration to Remove Arsenic from Contaminated Water

Background/Need: Groundwater containing arsenic contamination imposes a great threat to people worldwide as well as to the residents of the state of Wisconsin. Developing new and cost-effective methods to remove arsenic from groundwater and drinking water becomes imminent. With several patents granted, using iron/aluminum hydroxide to remove arsenic from water is a proven technology. However, the key issue is the filtration media. Currently, the filtration media used were limited to sand, granular activated carbon, granular activated alumina, but not zeolite.

Objectives: In this research, zeolite was proposed to use as the filtration media to remove arsenic-containing iron hydroxide co-precipitates. The hypothesis was that zeolite had a larger surface area and higher cation exchange and sorption capacity, and the use of zeolite in lieu of sand media to filtrate the arsenic containing iron hydroxide co-precipitates should be cost competitive to that of sand media while the performance would be much better than sand. Furthermore, due to an increase in capacity, less system faulting and less solid waste would be produced. In addition to removal of iron hydroxide co-precipitates, zeolite could also remove other undesired metal cations simultaneously.