Senior researcher Dr Biplob Pramanik and lead author Dr Nilufa Sultana examine treated kitchen wastewater. Their new grease interceptor design, developed at RMIT, dramatically improves fat removal. Credit: Will Wright, RMIT University
RMIT University
Key facts:
- RMIT researchers developed a new wastewater treatment system that removes up to 98% of fats, oils and grease (FOG), compared to 40% with traditional systems
- The system combines a redesigned grease interceptor featuring physical barriers with a specialised chemical treatment to capture both large and emulsified fat particles
- The system has proven effective in real-world conditions with high temperatures and detergent use
- The researchers say the technology can be scaled for different kitchen sizes and retrofitted to existing grease management systems, offering a cost-effective way to protect sewer infrastructure and reduce maintenance costs
- The research team is collaborating with water utilities and industry partners to further optimise the technology without chemical treatment
A new wastewater treatment system developed by RMIT University researchers could help prevent fatbergs – solid masses of fat, oil and grease (FOG) that clog sewers and cost water utilities globally billions to remove each year.
These congealed blockages, formed when FOG binds with wet wipes and other debris, reduce sewer capacity, trigger overflows and pose public health risks.
But a team from RMIT’s Effective Technologies and Tools (WETT) Research Centre has developed a solution that combines a redesigned grease interceptor with a smart chemical treatment – more than doubling fat removal rates in commercial kitchen wastewater.
“This is a major step forward in preventing FOG from entering our sewers from the biggest contributors: commercial food establishments,” said senior lead researcher and WETT Director Dr Biplob Pramanik.
“Traditional grease traps aren’t designed to catch the finer particles and emulsified fats in modern kitchen wastewater. Our system targets all fat types, even hard-to-remove emulsified fats that slip through conventional traps.”
The new design features a series of physical barriers, or baffles, inside a grease interceptor to slow wastewater flow and separate larger fat particles. A small dose of alum, a common water treatment chemical, is then added to clump smaller, suspended fats for easy removal.
Lead author Dr Nilufa Sultana said the system worked effectively even in real-world conditions with high temperatures and detergent use.
“While traditional interceptors only remove around 40% of fats, our system achieved up to 98% – even when tested with actual kitchen wastewater,” she said.
The researchers say the technology can be scaled for different kitchen sizes and retrofitted to existing grease management systems, offering a cost-effective way to protect sewer infrastructure and reduce maintenance costs.
Emeritus Professor Felicity Roddick said the implications went beyond infrastructure.
“Fat, oil and grease blockages can lead to sewage spills in our streets and waterways,” she said. “This research shows we can stop the problem at its source, with a simple upgrade to the systems food businesses already use.”
The RMIT team is developing a suite of integrated technologies to tackle fatbergs across the wastewater system.
Led by Pramanik, the team is collaborating with South East Water, Intelligent Water Networks, Water Research Australia, Barwon Region Water Corporation, Queensland Urban Utilities and the water technology company ACO on an ARC Linkage Project.
This project aims to optimise fluid dynamics within the grease interceptor to enhance the removal of fat, oil and grease without the need for chemical treatment, aligning with current industry practice.
The research article, ‘Performance optimization for the removal of fat, oil, and grease from food service establishment wastewater using a novel grease interceptor’, is published in ACS ES&T Water (DOI: 10.1021/acsestwater.5c00513).
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