Impact of changing environmental factors and species competition on iron filings‐based green environmental media for nutrient removal in stormwater treatment

Abstract

Iron filings‐based green environmental media (IFGEM) is a new type of green sorption media that may be applied to heterogeneous environments for removing nutrients. To confirm the reliability and efficacy of this new green sorption media, multiple factors must be considered for a holistic assessment, primarily temperature effect, varying influent concentration, changing pH value, varying iron filing content, presence of iron filings, and interaction (competition) between nutrient species such as nitrogen and phosphorus. In this study, two IFGEM recipes were selected to compare against one control (natural soil). Whereas IFGEM‐1 is made of 96.2% fine sand and 3.8% iron filings (by volume), IFGEM‐2 contains 80% sand, 10% tire crumb, 5% pure clay, and 5% iron filings (by volume). IFGEM‐1 can function well from 12 to 35°C, while IFGEM‐2 can work well only at the optimal temperature of 12°C. IFGEM‐2 may adapt to a wider pH range from acidic to neutral, while IFGEM‐1 performs well only at the neutral pH condition. When varying influent concentrations to test the sensitivity of both IFGEM recipes, our findings indicated that higher influent concentration results in higher removal efficiency. Higher iron filing content exhibits better nutrient recovery potential, and nitrogen and phosphorus compete for more shares of adsorption/adsorption capacity. © 2018 American Institute of Chemical Engineers Environ Prog, 38:e13087, 2019