Icon Water had not holistically upgraded the grit capture and transport functions at the Lower Molonglo Water Quality Control Centre (LMWQCC) since 1978. The grit removal system had underperformed. The grit system was imposing an unsustainable burden upon site-based personnel, requiring extremely labour-intensive annual cleaning with and the grit transfer lines blocked frequently, particularly in wet weather. Grit carryover also occurred frequently during wet weather that significantly disrupted downstream solids handling processes, particularly dewatering centrifuges and multiple hearth furnaces.
Modernising the existing grit removal system has significantly improved its operability, particularly during wet weather. The amount of manual labour required to clean each tank has more than halved, as has the amount of grit removed from each tank during cleaning. This project has been a prudent investment that has improved the resilience of Canberra’s primary wastewater treatment plant.
This paper outlines concept development and design, construction, commissioning, and early-life operational experience of the recently refurbished system. Of particular interest is the role played by computational fluid dynamics (CFD) in the design phase, novel construction approaches, and how contemporary online instrumentation and revised process control logic allows system performance to be accurately monitored and optimised.
Author
Steven Buck, Senior Process Engineer, Icon Water