Application of Magnetic Ion Exchange (MIEX) Technology

Magnetic Ion Exchange (MIEX) Technology is an advanced ion exchange process developed for the removal of dissolved organic carbons (DOC) from drinking water supplies. MIEX ® was developed by the water-care division of ORICA (Pty) Ltd, a leading Australian multinational corporation at the fore-front of developing advanced and innovative technology equipment.

Magnetic Ion Exchange (MIEX) Technology is uniquely different from conventional ion-exchange processes because it is designed specifically to be used in a continuous ion exchange process that utilizes the high surface area of the resin beads to provide ion exchange in a mixed or fluidised bed reactor at very low resin concentrations and short detention times.

The process of ion exchange is a two-stage process comprising of a high-rate mixed reactor and a resin regeneration system. In the high reactor, raw water is fed to the base of the reactor vessel and is mixed with the MIEX ® resin and the ion exchange process occurs in a uniformly mixed fluidized bed. In the fluidized bed the magnetic particles are attracted to each other to form large agglomerates that form a stable resin suspension at hydraulic loading rates of up to 20 m/hr. A series of plates (or tube settlers) at the top of the reactor vessel separate the resin from the water and treated effluent overflows into collection launders to downstream treatment processes.

A small volume of resin is continuously removed from the reactor vessel to the regeneration system. Fresh regenerated resin is returned to the reactor to maintain a consistent ion exchange capacity. The continuous withdrawal of loaded resin and return of regenerated resin ensures a consistent treated water quality and prevents the chromatographic peaking that can occur with conventional ion exchange columns. Brine solutions typically consist of NaCl but other salts such as KCl, MgCl2 or NaHCO3 can also be used if sodium or chloride is not desired in the waste discharge.

The objectives of DOC removal on water quality are:

• Removal of colour caused by DOC
• Reducing odour and taste levels in drinking water supplies
• Prevention of biological regrowth in distribution systems
• Impede the formation of disinfection by-products

The use of MIEX ® has process benefits which result in improved plant performance, as specified:

• Reduced chemical usage (Lime, coagulant & floc)
• Improved filtration
• Reduced sludge production
• Reduced energy consumption compared to rival technologies
• Potential for increased plant treatment capacityMagnetic Ion Exchange (MIEX) Technology.