Phosphate removal by iron oxide-coated diatomite: Laboratory test of a new method for cleaning drainage water

TY - JOUR

T1 - Phosphate removal by iron oxide-coated diatomite

T2 - Laboratory test of a new method for cleaning drainage water

AU - Lyngsie, Gry

AU - Katika, Konstantina

AU - Fabricius, Ida Lykke

AU - Hansen, Hans Christian Bruun

AU - Borggaard, Ole Kragholm

PY - 2019/5/1

Y1 - 2019/5/1

N2 - Transport of phosphate (P) in drainage water from P rich agricultural fields to freshwaters via drains may cause open water eutrophication. One way to reduce this transport is by installation of P sorbing filters at drain outlets. As drainage water flows and P concentrations can be highly fluctuating, suitable filters must have good hydraulic conductivity and high P sorbing efficiency, i.e. rapid sorption with high affinity and capacity. To fulfill these requirements, we tested a new concept for filter material design comprising porous and stable calcined diatomaceous earth particles (CDE, 2–4 mm) coated with thin layers of high affinity P sorbing amorphous iron oxide. According to NMR and MICP analyses the material had a bimodal pore size distribution with average diameters of around 1 μm and 100 μm. The coating formed a thin film on the CDE internal and external surfaces and markedly increased the P sorption efficiency. Thus, P in 0.1 and 0.5 mg P/L solutions was almost quantitatively sorbed within 1½ min at a solution:solid ratio of 100. SEM-EDX demonstrated that P quickly penetrated into the porous structure of the CDE granules and that all Fe in the coating was active in P bonding. This conceptual investigation demonstrates that porous CDE is a useful host into which Fe oxides can be precipitated resulting in an effective P sorbing material.

AB - Transport of phosphate (P) in drainage water from P rich agricultural fields to freshwaters via drains may cause open water eutrophication. One way to reduce this transport is by installation of P sorbing filters at drain outlets. As drainage water flows and P concentrations can be highly fluctuating, suitable filters must have good hydraulic conductivity and high P sorbing efficiency, i.e. rapid sorption with high affinity and capacity. To fulfill these requirements, we tested a new concept for filter material design comprising porous and stable calcined diatomaceous earth particles (CDE, 2–4 mm) coated with thin layers of high affinity P sorbing amorphous iron oxide. According to NMR and MICP analyses the material had a bimodal pore size distribution with average diameters of around 1 μm and 100 μm. The coating formed a thin film on the CDE internal and external surfaces and markedly increased the P sorption efficiency. Thus, P in 0.1 and 0.5 mg P/L solutions was almost quantitatively sorbed within 1½ min at a solution:solid ratio of 100. SEM-EDX demonstrated that P quickly penetrated into the porous structure of the CDE granules and that all Fe in the coating was active in P bonding. This conceptual investigation demonstrates that porous CDE is a useful host into which Fe oxides can be precipitated resulting in an effective P sorbing material.

UR - http://www.scopus.com/inward/record.url?scp=85061658499&partnerID=8YFLogxK

U2 - 10.1016/j.chemosphere.2019.01.158

DO - 10.1016/j.chemosphere.2019.01.158

M3 - Journal article

AN - SCOPUS:85061658499

SN - 0045-6535

VL - 222

SP - 884

EP - 890

JO - Chemosphere

JF - Chemosphere

ER -