Design and Construction of the World`s First Large Scale MIEX® Water Treatment Plant
The Water Corporation of Western Australia has over a number of years been investigating various water treatment technologies aimed at dissolved organic carbon (DOC) removal. Research was prompted by intermittent outbreaks of DMTS (Dimethyl Trisulphide) in the clearwater distribution system. The presence of DMTS in tap water is noted as a “swampy” odour, and is suspected to be the product of biological action in the distribution system. DOC in the treated water promotes biofilm growth in the distribution system, and this coupled with NSRS (non-sulphide-reduced-sulphur) in the water leads to DMTS formation (Franzmann et al 1999). With elevated levels of DOC linked to the formation of DMTS, the MIEXÒ Process was trailed at Wanneroo Groundwater Treatment Plant (GWTP), a currently used source of DMTS affected water.
After two years of pilot plant and laboratory work, the Water Corporation of Western Australia has initiated the design and construction of the world’s first large scale MIEXÒ plant. Black and Veatch Australia has been appointed as the Engineer, Procure and Construct (EPC) contractor for delivery of the MIEXÒ plant at Wanneroo groundwater treatment plant. The total cost of the EPC contract is on the order of $15M AUD. The full scale MIEXÒ train will have a capacity of 112.5 MLD, and include the provision for a second train to be added if required. The existing Wanneroo plant has a peak capacity of 225 MLD with a variety of bores (50 in total) supplying the raw water.
The MIEXÒ Process differs from conventional ion exchange technology in that the ion exchange part of the process is continuous. The resin is regenerated in a separate area of the plant. The particle size of the resin is considerably smaller than conventional ion exchange resins (150 to 180 microns). High recovery rates of 99.9% are possible due to the magnetic properties of the resin. Once mixing energy is removed, the resin beads attract to one another to form large agglomerates with a high settling velocity (25 m/hr). This affords the use of settling tanks with up flow rates in the region of 10 to 15 m/hr.