11.4 Wastewater collected
a. Wastewater collected
The volume reported (91,043 ML) represents the total volume of wastewater collected and transferred to wastewater treatment plants (WWTPs) within the Adelaide region.
This volume includes wastewater discharged to the sewer after usage and any variation due to (a) ingress of stormwater; (b) infiltration of groundwater; (c) wastewater overflows to stormwater; and (d) exfiltration of wastewater to groundwater.
|WWTP||Metered inflow (ML)|
|Bolivar High Salinity||8,405|
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 inflow to each WWTP within the Adelaide region was obtained from SA Water's WWTP records. Metered flows are either automatically logged by SCADA or manually read and recorded by plant operators. Inflows for each wastewater treatment plant were aggregated.
Assumptions, limitations, caveats and approximations
This does not include wastewater collected for individual community wastewater management systems.
This includes wastewater collected from outside of the Adelaide region and delivered to the Bird-in-Hand WWTP. Data on the breakdown between wastewater collected within and outside the region were not available; however, the volume from outside the region is assumed to be negligible.
Uncertainty is +/– 10% based on meter calibrations.