Which is the Best Oxidant for Complexed Iron Removal from Groundwater: The Kogalym Case

摘要

A short overview of the significance of a preoxidation stage groundwater treatment is presented. As an example the case of complexed iron removal from Kogalym groundwater (Tjumen, Siberia, Russian Federation) using different preoxidants (ozone, oxygen, chlorine, hydrogen peroxide, and potassium permanganate) is discussed. The key problem is stable di-and trivalent iron-organic complexes in groundwater which after aeration tend to pass through the hydroanthracite-sand gravity filters. The total organic carbon (TOC) content in raw groundwater is in the range of 3.2-6.4 mg/L, total iron content 2.7-6.0 mgjL and divalent iron content 2.4-4.0 mg/L. Separation from Kogalym groundwater by XAD-16 adsorbent humic matter fraction was homogeneous, with only 1 peak on the chromatogram with maximum Rt = 10.75 min and corresponding molecular mass 1911 (<2000). The final developed treatment technology is based on the water oxidation/ reduction potential (ORP) optimization according to the iron system pE-pH diagram and consists of intensive aeration of raw water in the Gas-Degas Treatment (GDT) unit with the following sequence: filtration through the hydro-anthracite and special anthracite Everzit, with intermediate enrichment of water with pure oxygen between the filtration stages.