19.7 Wastewater discharge outside of region
a. Wastewater discharge outside of region
The volume reported (59,264 ML) represents discharge from five wastewater treatment plants (WWTPs) in the Adelaide region to the sea. The following table details the volume of wastewater discharged to sea during the 2012–13 year from each respective WWTP.
|Bolivar High Salinity||7,874|
1All wastewater treated at the Aldinga WWTP was recycled for use in the 2012–13 year
b. Wastewater system overview
The wastewater system is one of three subcomponents of Adelaide's urban water system. The three subcomponents are the:
- urban water supply system
- wastewater system
- recycled water system.
In the Adelaide region, wastewater is collected (line item 11.4 Wastewater collected) from users and treated by SA Water at one of their wastewater treatment plants.
During the 2012–13 year the majority (64%: line item 19.7 Wastewater discharge outside of region) of treated wastewater was discharged to sea; approximately 32% was recycled (see recycled water system overview) and the remaining portion was either discharged to surface water (2%: line item 19.5 Discharge from urban water system to surface water) or lost during wastewater treatment processes (2%: part of line item 19.20 Other urban water system decreases).
The following figure shows all the inflows and outflows associated with the wastewater system. For more detail on a particular flow associated with the wastewater system, refer to the line item notes. The small misbalance shown (1.5%) can be attributed to metering inaccuracies, unaccounted losses and inaccuracies in the estimation of the recycled water on-site in process use.
Note that volumes annotated with an asterisk (*) indicate flows between subcomponents of the urban water system and are not reported in the account. As such, these flows do not have an associated line item number.
Schematic diagram of water inflows and outflows for Adelaide's recycled water system during the 2012–13 year; line item numbers are provided in brackets
The metered volume of wastewater discharged to sea was obtained from SA Water's WWTP records. Metered flows are either automatically logged by SCADA or manually read and recorded by plant operators.
Assumptions, limitations, caveats and approximations
Uncertainty is +/– 10% based on meter calibrations.