title: Estimating the risk from sewage treatment plant effluent in the Sydney catchment area.
abstract: This study employed Quantitative Microbial Risk Assessment (QMRA) to estimate the gastrointestinal risks associated with Cryptosporidium and Giardia discharged from three STPs located within the Lake Burragorang catchment. The QMRA considered baseline and various hazardous event scenarios (e.g. plant failure and heavy rainfall). Under baseline conditions, the combined effect of constructed barriers, catchment barriers and dilution reduced pathogen numbers from the discharge of all three STPs by 10 to 14 orders of magnitude. This was sufficient for the risk to be well below currently mooted benchmarks of 'tolerable risk', even when relatively conservative assumptions were applied. For all hazardous event scenarios, the level of risk remained low, which illustrated the benefit of multiple barriers. Provisionally it appears that the STPs currently discharging into the waterways of the catchment do not pose an unacceptable or unmanageable risk to Sydney's drinking water consumers.
authors.affiliation: UNSW Water Research Centre, University of New South wales, Sydney, NSW 2052, Australia. b.vandenakker@unsw.edu.au
authors.forename: B
authors.initials: B
authors.lastname: van den Akker
authors.forename: V
authors.initials: V
authors.lastname: Whiffin
authors.forename: P
authors.initials: P
authors.lastname: Cox
authors.forename: P
authors.initials: P
authors.lastname: Beatson
authors.forename: N J
authors.initials: NJ
authors.lastname: Ashbolt
authors.forename: D J
authors.initials: DJ
authors.lastname: Roser
mesh_terms: D003458:Cryptosporidium / Q000302:isolation & purification; D004203:Disinfection; D005872:Giardia / Q000302:isolation & purification; D009517:New South Wales; D012307:Risk Factors; D012722:Sewage; D014865:Waste Disposal, Fluid; D014867:Water / Q000469:parasitology; D014871:Water Microbiology; D014876:Water Pollution / Q000517:prevention & control*; D018508:Water Purification / Q000379:methods
chemical_list: D012722:Sewage; D014867:Water