Determining which iron minerals in iron-enhanced sand filters remove phosphorus from stormwater runoff

Excess phosphorous is a water quality problem affecting storm runoff, rivers, and lakes in urban and agricultural
settings throughout Minnesota, causing algal blooms, making lakes green, and negatively affecting fish and
wildlife. More than 50 iron-enhanced sand filter basins have been installed throughout Minnesota since 2009 to
remove phosphorous from water, and many more are scheduled for installation with costs ranging from $30k-
$300k each. The physical and hydrological properties of iron-enhanced sand filters are well known, but their
chemical properties are not (Table 1), and despite wide success, some iron-enhanced sand filter systems that are
currently installed are not working effectively. There is an initiative by designers to secure a local source of iron
with consistent chemical characteristics for more consistent filter results and to minimize substantial shipping
cost, but any iron source needs to be tested for effectiveness prior to acquisition, and we currently do not know
which chemical and mineralogical characteristics of iron are optimal for filter effectiveness and longevity. We
hypothesize that only certain iron minerals will remove phosphorous from water, and our proposed work is to
determine which iron minerals make iron-sand filters work efficiently.

Determining which iron minerals in iron-enhanced sand filters remove phosphorus from stormwater runoff midproject presentation June 2018 .pdf
Midproject report .pdf
2019 Midproject Presentation .pdf
Final report .pdf

Project Staff: 

PI Beth Fisher, UMN Earth Sciences, Joshua Feinberg, UMN Earth Sciences, John Gulliver, Civil Engineering, Chris Meehan, Wenck Associates