Manganese Control: A Back to the Basics Approach Stops Customer Complaintsand Works with Unconventional Processes

摘要

For many utilities the aesthetic problems that accompany elevated manganese levels are ofrnparamount concern. Unsightly deposits and colored water problems cause innumerablerncomplaints in some systems. Such conditions can occur even when manganese levels are belowrnthe 0.05 mg/L secondary standard, causing some utilities to set internal goals of 0.015 or 0.02rnmg/L. Results from two projects are presented in this paper.rnIn recent years, the Hyde Park Water Treatment Plant has received customer complaintsrndescribed as "dirty water" or "pinkish water". In addition, dark brown or black deposits havernformed on some of the plant equipment and the walls of the clearwell and a dark sediment/filmrnwas observed in a storage tank. These complaints and deposits were determined to be caused byrnmanganese passing through the treatment plant after process changes were implemented to reducerndisinfection byproduct levels.rnUpgrades to the Stamford Water Treatment are currently being designed. The raw water supplyrnis a reservoir that undergoes stratification. During the late summer period, elevated manganesernlevels caused by anoxic conditions in the bottom waters and taste and odor episodes caused byrngeosmin and MIB are the major treatment concerns. Manganese is controlled by the inducedgreensandrneffect that occurs when chlorine is added prior to anthracite or sand filters. Conversionrnto GAC filters to control the taste and odor events may inhibit the induced-greensand effect.rnManganese control, although not a health issue, is essential for maintaining consumer confidence.rnThe results of this paper will help utilities that experience difficulty in controlling manganese. Itrnwill also help utilities considering treatment changes to reduce DBPs or control taste and odors torndo so in a manner that will not compromise manganese removal.