Overview

St Marys Water Resource Recovery Facility is one of about 30 water resource recovery facilities in Greater Sydney. Wastewater is treated to a tertiary standard. The recycled water is reused onsite, for irrigating a local golf course and as environmental flows to the local creek. The rest of the water is then sent to the St Marys Advanced Water Treatment Plant for further treatment using membrane technology with subsequent release of the water into the Hawkesbury Nepean River for environmental flow.

The solids from various treatment processes are collected and dewatered before they are processed through the THP (Thermal Hydrolysis Process) and anaerobic digestion process to produce class A biosolids for offsite beneficial use. The biogas produced from the digestion process is used on-site to operate the boilers for the THP and cogeneration system to produce electricity for site usage. Excess biogas is flared through the waste gas burners and excess electricity is put back onto the grid.

Unit operations include physical separation processes for primary treatment (screening, grit removal, sedimentation), secondary treatment (bioreactor and secondary clarifier) and tertiary treatment (tertiary clarifier, filtration and disinfection). Features of interest include THP (Thermal Hydrolysis Process) and a cogeneration system.