Mechanistic understanding of multiple beneficial aspects of iron-salts & iron-rich waterworks sludge uses in integrated urban wastewater system – Lessons learned from lab-scale, pilot, & field studies
Dr. Sohan Shrestha completed his PhD in 2020 from Advanced Water Management Centre (AWMC), School of Chemical Engineering, The University of Queensland (UQ), Brisbane, Australia. Currently, he works as researcher & water treatment operator for Arris Water Pty Ltd.

There has been growing interest in integrated iron(Fe)-salts or waterworks Fe-rich sludge uses for system-wide operation, aiming to reduce the overall chemical footprint of urban water utilities.

The multiple beneficial uses of iron (either in the form of iron-salt or iron-rich sludge) in sewer system and downstream wastewater treatment plant in an integrated manner have found to achieve sulfide removal in sewers (decreasing sewer odour and corrosion), phosphorus (P) removal during wastewater treatment, hydrogen sulfide (H2S) removal during digester biogas generation, including improving the sludge settleability and dewaterability during wastewater treatment processes.

When adopting such integrated strategy of in-sewer iron-dosing, iron is reused four times during transit through the treatment chain of urban wastewater system thereby substantially reducing chemical usages. 

The project outcomes identified clear opportunities for water and wastewater utilities to collaborate, and share the benefits, providing water/wastewater services in a cost-effective manner albeit with improved environmental sustainability.

The current presentation will primarily shed light on the underlying mechanism behind some key beneficial aspects when implementing iron-dosing in integrated sewer-wastewater treatment plant.