Full Scale Magnetic Ion Exchange Process Tested by Historically High DOC Levels

The Aireys Inlet Water Treatment Plant (WTP) is located about 150 kilometres from  Melbourne on the Great Ocean Road. The WTP utilises a conventional upflow sludge blanket clarification process. The raw water source for this plant is characterised by high DOC levels. Despite operating in an enhanced coagulation mode sufficient DOC removal was not able to be achieved. This resulted in high chlorine demand at the plant, quick chlorine decay, low chlorine residuals and in turn bacterial regrowth in the distribution system. In addition, the reaction of chlorine with DOC led to the formation of elevated concentrations of disinfection by-products.

Installation of a MIEX® Plant in December 2004 has resulted in the following performance improvements:-

  • Increased DOC removal from 40-50% to 60-80%; 
  • Reduced THM levels by approximately 60% to levels below the requirements of the US EPA Disinfection By-Product Rule Stage 1; 
  • Improved the operational stability of the downstream conventional treatment process; and 
  • Improved customer satisfaction.

This has been achieved despite a significant deterioration in raw water quality and without a significant increase in operational costs.

The Aireys Inlet Water Treatment Plant (WTP), located about 150 kilometres from  Melbourne, is operated by Barwon Water and sources its raw water from the Painkalac  Reservoir. The raw water contains high levels of colour and dissolved organic carbon (DOC). These factors combined with low alkalinity and variable turbidity make this water very difficult to treat.  A continuous magnetic ion exchange (MIEX®) plant was installed in December 2004 as
raw water pre-treatment for the existing 2.85 megalitre per day (MLD) conventional plant.  MIEX® pretreatment has significantly reduced treated water dissolved organic carbon (DOC) levels and disinfection by-product (DBP) formation, reduced treatment chemical consumption and improved WTP stability.

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