Using oxidation–reduction potential to manage media filters treating sulfide-laden groundwater

摘要

An evaluation studying the use of oxidation-reduction potential (ORP) for optimizing a 10,500 m(3)/d (2.8 MGD) oxidizing media filter (OMF) process treating Floridan groundwater containing between 1.6 and 1.8 mg/L sulfide has been completed. One year after placing the OMFs on-line, colored water complaints were reported within the municipal water system. It was determined that the filter beds required regeneration as they were insufficiently oxidized, and the media's manganese dioxide coating was being released into the finished water. ORP, free chlorine residual, total manganese and turbidity measurements were recorded during filter run cycles before and after each regeneration event. Results showed that below 500 mV ORP was a more useful measurement for monitoring regeneration events within the media bed than chlorine residual which was not detectable. Results showed a significant increase in turbidity (2 NTU) and total manganese ( 0.05 mg/L) when the ORP within the filter bed dropped below 400 mV. More frequent cycling of the filters was found to be an effective treatment option to maintain ORP values above 600 mV as an operational threshold.