South East Queensland
19.7 Wastewater discharge outside of region

The volume for the line item during the 2012–13 year was 183,894 ML.

This line item consists of wastewater system and recycled water system discharges to the sea, estuaries, and inlets outside of the South East Queensland (SEQ) region.

Discharge from wastewater system

A number of wastewater treatment plants (WWTPs) discharge treated wastewater to the sea, estuaries, and inlets outside of the SEQ region. Discharges to freshwater rivers, creeks, and other surface water are reported in line item 19.5 Discharge from urban water discharge to surface water. A number of WWTPs that discharge to the Brisbane River are included in this line item, as the Brisbane River is estuarine through much of the urban Brisbane area.

Discharge from advanced water treatment

Reverse osmosis brine concentrate and excess purified recycled water from the Gibson Island and Luggage Point advanced water treatment plants (AWTPs)  were discharged to the Brisbane River estuary as part of the Western Corridor Recycled Water Scheme treatment process.

The volume of wastewater collected by the wastewater system during the 2012–13 year (11.4 Wastewater collected) was 244,668 ML.  The majority of the outflow from the wastewater system (74%) was treated wastewater discharged to sea (19.7 Wastewater discharge outside of region); approximately 16% was discharged to surface water (19.5 Urban water discharge to surface water); and approximately 9 % was recycled. The remainder (1%) comprised a small volume of treated wastewater discharged to landscape and losses from wastewater system.

The following figure shows all the inflows and outflows associated with the wastewater system. There was some unaccounted flow in the wastewater system that produced an error of  0.4% of total wastewater system inflows. 

For more detail on a particular flow associated with the recycled water system, refer to the line item notes. Note that volumes annotated with an asterisk (*) indicate flows between sub-components 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 during the 2012-13 year for South East Queensland's wastewater system; line numbers are provided in brackets

Approximately 7% of urban water consumption (236,941 ML) came from the recycled water system and from advanced water treatment.

During the 2012–13 year, approximately 55% of the recycled water produced (23,241 ML) was supplied to urban users. Approximately 13% of the recycled water was used on-site at wastewater treatment plants (WWTPs) throughout the region while approximately 20% was used in-process (recirculated) and the rest was delivered for advanced water treatment. There was some unaccounted flow in the recycled water system inflows that produced an error of (1%) of total recycled water supply system inflows.The following figure shows all the inflows and outflows associated with the recycled water system and advanced water treatment.

For more detail on a particular flow associated with the recycled water system and advanced water treatment, refer to the line item notes. Note that volumes annotated with an asterisk (*) indicate flows between sub-components 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 during the 2012–13 year for South East Queensland's recycled water system; line item numbers are provided in brackets

 * due to data discrepancies, it was assumed that inflow into recycled system equalled to the recycled water usage.

Seqwater: WaterHub database; 

Council of the City of Gold Coast, Logan City Council, Queensland Urban Utilities: datasheets via Queensland Water Directorate (Qldwater).

Council of the City of Gold Coast; Logan City Council; Queensland Urban Utilities; Seqwater.

Discharge from Wastewater system

The volume of treated wastewater discharged to outside the region was provided by the water utilities. Where necessary, in order to confirm the volume discharged to outside the region, further information about the discharge points was sought from the utilities. When treated water discharges to surface water close to the river mouth (discharge point to ocean) it is considered as discharge to sea as reported by the water utilities.

Discharge from advanced water treatment

Annual advanced wastewater treatment plant (AWTP) discharge data for reverse osmosis concentrate and excess purified recycled water were obtained from Seqwater datasets for Gibson Island and Luggage Point AWTPs.

Nil

The uncertainty was not quantified.