| The first objective of this research was to evaluate oxidation-reduction potential (ORP) as an indicator of effective iron removal in a biological process and to determine its relationship to dissolved oxygen (DO) and residual iron in the filtered water. Biological removal of iron to produce drinking water was established on one full-scale and two pilot-scale plants at two sites in France. Results show that below a minimum DO concentration of approximately 0.3 mg/L, residual iron concentration was related to ORP in the filtered water. Above the minimum DO requirement, ORP on the order of approximately 500 mV consistently reflected effective iron treatment and residual iron concentrations less than the French norm for potable water of 0.2 mg/L.;Secondly, two catalytic materials of filtration known as Ferrolite MC2 and Purolite were investigated on pilot-scale for their capacity to oxidize iron and manganese. Results showed that both materials eliminated dissolved iron to below detection levels regardless of DO or filtration rates up to 15 m/h (Ferrolite MC2) and 20 m/h (Purolite). During the trial period where no filter regeneration was carried out, the elimination of dissolved iron and dissolved manganese, respectively, were 100% and 77% for Purolite and 100% and 65% for Ferrolite MC2 for a raw water with 3.47 mg/L of dissolved iron and 0.317 of dissolved manganese. Purolite filtered a total volume of 1127 L or 137 L/kg of catalytic material and Ferrolite MC2 filtered a total of 1457 L or 217 L/kg. |
