The Modelling Water Quality and Treatment session will deal with novel modelling approaches that are used, or could be used in the treatment of source waters (fresh or saline) for drinking purposes, the treatment of domestic and industrial wastewaters discharged into the environment and/or used for recycling purposes. These might include modelling for prediction of chemical use, such as coagulants, pH control reagents and disinfectants, prediction of water/wastewater quality changes with treatment, pollutant removals from wastewaters and mathematical approaches applied to assess treatment efficiencies.