AWWA MTC57618

AWWA MTC57618 Simultaneous Oxidation: Coagulation Using Immersed Membranes for the Removal of Dissolved Organics and Iron and Manganese
Conference Proceeding by American Water Works Association, 03/05/2003

Singh, M.; Eng, M.; Kendrick, S.; Best, G.; Eng, P.; Painchaud, C.; Crawford, S.; Bach, D.

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The presence of iron and manganese in drinking water distribution systems is a concern as itreduces the aesthetic quality of the water. When dissolved iron and manganese are oxidized, theyform insoluble compounds that precipitate and cause yellowish to reddish-brown to blackstaining, depending on the relative abundance of each metal. In order to improve the aestheticquality of drinking water, the US Environmental Protection Agency National Secondary Drinking Water Regulations suggestmaximum concentrations of 0.30 mg/L and 0.05 mg/L for iron and manganese, respectively. TheZeeWeed(R) Ultrafiltration Membrane system can remove particles that are greater than 0.1microns in size, including iron and manganese precipitates. For the removal of dissolved iron andmanganese, an oxidation step is added prior to the membrane, which converts the dissolvedspecies into their insoluble forms. Oxidation may be achieved by aeration or by the addition ofoxidizing chemicals such as chlorine, chlorine dioxide or potassium permanganate.For water sources requiring both removal of dissolved organics and dissolved iron andmanganese, ZENON has developed a unique process in which the ZeeWeed(R) UltrafiltrationMembrane system can be coupled with a single step coagulation-oxidization process. This paperdiscusses critical process issues required to prevent membrane fouling and to achieve thetreated water quality objectives with respect to organics and iron and manganese removal whileutilizing the simultaneous step coagulation-oxidation process. This paper also presents theresults from numerous pilot studies conducted to demonstrate the capabilities of ZeeWeed(R) 500immersed membrane system to combine both of these pretreatment steps. A detailed discussionevaluates the effects of different operating parameters on TOC, color, iron andmanganese removal from surface waters and groundwaters. Includes 4 references, tables, figures.