Formation pathways for iron oxide minerals and geochemical conditions for phosphate retention in iron enhanced sand filters

Abstract

Our overall goal for this project was to better understand the geochemical and mineralogical processes within Iron Enhanced Sand Filters (IESFs) that lead to effective removal of phosphorus. Our specific objectives were to (1) identify the most effective iron minerals for phosphorus trapping, (2) provide a screening method to optimize the success of Iron Enhanced Sand Filters (IESFs) to trap iron, (3) determine if iron minerals within filters get used up or remain active over time, and (4) use real time monitoring to understand IESF chemical conditions and dynamics. We thus structured our research activities and findings around answering these four questions: 1. What are the most effective minerals for phosphorus trapping? 2. Is there a method to screen iron sources prior to acquisition? 3. Do the iron minerals in the filter get used up over time? 4. Monitoring: Is the water and filter chemistry conducive for effective iron- phosphorus bonding?