Vivianite precipitation for iron recovery from anaerobic groundwater

Vivianite precipitation for iron recovery from anaerobic groundwater

Goedhart, R.C. (TU Delft Sanitary Engineering)
Müller, S. (TU Delft Sanitary Engineering)
van Loosdrecht, Mark C.M. (TU Delft BT/Environmental Biotechnology)
van Halem, D. (TU Delft Sanitary Engineering)

2022

Iron in anaerobic groundwater is commonly removed by oxidation followed by sand filtration. This produces large volumes of iron(III)(hydr)oxide sludge with little value. Our research investigates the novel concept of anaerobic iron(II) recovery from groundwater as the valuable mineral vivianite (Fe₃(PO₄)₂ • 8 H₂O) by the addition of phosphate to the water. We found that vivianite precipitated both in synthetic and natural groundwater when the saturation index (SI) was higher than 4. The SI can be increased by elevating the pH, which allows for iron removal at lower concentrations. Anaerobic iron removal reached 93.7% in natural groundwater, which increased further to 99.9% after a subsequent aeration step. Vivianite precipitation followed second order kinetics with a rate constant of 2.3 M⁻¹s⁻¹ and the sludge volume decreased by two third compared to iron oxidation. We therefore conclude that anaerobic iron removal is a promising new approach towards sustainable groundwater treatment.

Drinking water
Groundwater
Iron
Treatment
Vivianite

http://resolver.tudelft.nl/uuid:5a79867e-889b-4e44-a7bf-28be4dd44658

https://doi.org/10.1016/j.watres.2022.118345

0043-1354

Water Research, 217

Institutional Repository

journal article

© 2022 R.C. Goedhart, S. Müller, Mark C.M. van Loosdrecht, D. van Halem