1. Department of Civil and Environmental Engineering, Water Environment Technology, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
2. Department of Parasitology, Mycology, Water and Environmental Microbiology, Swedish Institute for Infectious Disease Control, SE-171 82 Solna, Sweden
3. Göteborg Water, City of Göteborg, Box 123, SE-424 23 Angered, Sweden