1. School of Water Science, Cranfield University, Cranfield, MK43 0AL, UK
2. Anglian Water Services, Thorpe Wood House, Thorpe Wood, Peterborough, PE3 6WT, UK
3. Silsoe Research Institute, Wrest Park, Silsoe MK45 4HS, UK
4. Centre for Water and Waste Technology, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia