grease recovery rea systems

When the City of Danbury decided to renovate its wastewater treatment plant, it incorporated our FOG-To-Biodiesel system to eliminate the economic and environmental costs associated with landfilling and incinerating its waste FOG. The system not only eliminates their FOG disposal costs, but creates a new revenue stream from the sale of biodiesel they produce onsite without interruption to the operation of their plant, through an automated and continuous-flow process.

For this project, we designed an 18,000 GPD FOG receiving station to increase Danbury’s capacity to accept trap grease trucked in by grease collectors. To address concerns about odor emanating from the process of receiving FOG and converting it to biodiesel, odor-control equipment is embedded into our system.

During preprocessing, we eliminate 99% of water content to prepare the brown grease for conversion to biodiesel. Water separated in the this process is fed back into the treatment system, from where it discharges as effluent.

Biodiesel not consumed by Danbury will be sold to a local fuel distributor for a considerable profit through an off-take agreement. Over the past 10 years, B100 biodiesel has been consistently priced higher than most other other alternative fuels.

For municipalities interested utilizing their biodiesel production to fuel their fleets, they can reduce respective carbon emissions by up to 74%. Life-cycle analysis conducted by Argonne National Laboratory concluded emissions for B100 biodiesel to be 74% lower than those from petro-diesel. The California Air Resources Board has also generated similar results for its life-cycle analysis of biodiesel.

FOG is commonly mixed with sludge and utilized as a co-substrate in anaerobic digesters for solids volume reduction and biomethane production. Replacing FOG with glycerin, a byproduct of our FOG-To-Biodiesel system, can increase volatile solids removal and biogas production. With our FOG-To-Biodiesel system, more energy (and value) can then be produced with the FOG that would have otherwise been fed to the digester.


Eliminates environmental and economic costs associated with FOG disposal
Creates energy and a new revenue stream from biodiesel produced from waste FOG
Works cooperatively with digesters to increase volatile solids removal and biogas production
A profitable solution that also helps meet organizational ESG goals