ENHANCED COAGULATION USING A MAGNETIC ION EXCHANGE RESIN
Philip C. Singer, Professor
Katya Bilyk, Graduate Research Assistant
Department of Environmental Sciences and Engineering
University of North Carolina
Chapel Hill, NC
Introduction
The objective of this investigation was to examine the effectiveness of a magnetic ion
exchange resin (MIEX®) provided by ORICA Australia Pty Ltd. of Victoria, Australia to
enhance the coagulation of disinfection by-product (DBP) precursors. The MIEX® resin
purportedly adsorbs natural organic material, thereby lowering the coagulant demand of
the water, as well as lowering its DBP formation potential. Pre-treatment of raw drinking
waters with MIEX® was evaluated to determine its impact on subsequent coagulation of
raw drinking water with alum and on subsequent DBP formation following chlorination.
Background
The MIEX® process is based on a new patented ion exchange resin developed by
ORICA. The resin combines a number of anion exchange resin features intended to
result in efficient removal of natural organic material. It has a polyacrylic, macroporous
structure with a medium pore size and porosity. It also contains a high concentration of
strong base, quaternary ammonia functional groups.1
The MIEX® resin particle size is 2-5 times smaller than conventional resins, which are
restricted to larger sizes because they tend to be used in fixed bed configurations where
head losses need to be minimized. Smaller resins show higher rates of exchange because
they have larger external specific surface areas. Accordingly, they have more active sites
on the surface of the resin beads. As a result, the reliance on slow, intraparticle diffusion
associated with active sites inside resin beads is correspondingly reduced.
A major feature of the resin that allows it to be used in a batch treatment mode is the high
content of a magnetic compound which is integrated into the resin structure. Because of
this magnetic property, the resin beads can