Urban water

Managing nitrogen releases to waterways from sewage treatment plants (STPs) is an important part of aquatic ecosystem health protection to reduce risks of harmful or nuisance algal blooms occurring.

Sewage treatment plants are responsible for the largest point source nutrient loads delivered to waterways in South East Queensland.

Wastewater service providers of South East Queensland are servicing a rapidly growing population and are investing in managing the associated increases in sewage treatment demands. These environmental management activities may relate to design, operation, maintenance or monitoring of wastewater treatment processes.

A key indicator of the level of practice in the context of managing impacts on receiving waters in highly urbanised areas, where there is sustained and ongoing wastewater release, is the rate of efficiency of nitrogen removal from wastewater.

The Queensland Government has released guidelines for Leading Practice Sewage Treatment Plant Environmental Management. Nitrogen removal efficiencies for sewage treatment plant operators in SEQ were estimated based on publicly available data for sewage service providers of SEQ to assess the level of practice, based on these guidelines. Using 60mg/L as the average concentration of nitrogen in untreated sewage, the equivalent % nitrogen removal efficiency thresholds are:

• Leading Practice 1: 96.7% removal.
• Leading Practice 2: 94.2% removal.
• Leading Practice 3: 91.7% removal.

Here's a snapshot of just some of the action over the past 5 years. These numbers will grow as more groups from across the region contribute their data.