New tech helps manage FOG at collection and food production sites

grease trap
Restaurant and food processing grease traps can be quickly overwhelmed if not regularly maintained. Credit: antpkr, AdobeStock

By Brian Levine

Grease is not a new challenge for the municipal wastewater industry, but it is becoming increasingly problematic. Annually, there are thousands of sanitary sewer overflows, with fats, oils and grease (FOG) often being a contributing factor.

FOG is the byproduct of cooking with animal fats and vegetable oils. The largest source of grease comes from restaurants, commercial kitchens and industrial food processing facilities. Although food service and food processing establishments are expected to follow strict guidelines for grease trap waste disposal, grease traps can be quickly overwhelmed if not regularly maintained. This allows FOG to enter sewer lines where it cools and solidifies. Over time, the accumulated FOG can block pipes completely, causing backups.

It has been estimated that grease trap waste and uncollected grease entering sewage treatment plants ranges from 365 kg to 7,700 kg of grease per restaurant, per year. In response, municipalities continue to adopt more stringent regulations, detailing how food preparation and food processing businesses handle and dispose of grease.

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The current COVID-19 world health crisis is further complicating the FOG problem for municipalities. With the vast majority of people under “stay at home” directives and an increased reliance on take-out, prepared foods and home cooking, residential FOG is on the rise, contributing to costly and inconvenient sewer backups. Municipalities spend considerable monies annually to unclog sewer pipes and repair sewer lines and other damage caused by improper disposal of FOG.

What can be done with FOG?

Grease trap waste is usually transported to receiving stations at select municipal sewage or commercial wastewater treatment plants where haulers pay fees to dump their loads. However, there is a dire shortage of FOG processing solutions and centres and this limits disposal options.

Downey Ridge Environmental Company developed Greasezilla, a hydronic thermal separation and conversion technology, to manage FOG at collection sites and large-scale food production facilities where high volumes of FOG are generated. The patented separation technology removes nearly all grease at the front end without the need for polymers, flocculants or landfilling.

The Greasezilla system heats the grease trap waste, separating it into three distinct layers: residual pasteurized effluent, batter and rich brown grease. The batter can be used as a feedstock for anaerobic digesters or treated with traditional processes. Brown grease is pumped into holding tanks.

Annually, a standard system permits a site to process up to 30 million litres of grease trap waste, while producing a premium, low moisture, high FFA brown grease (advanced biofuel) offtake. This advanced biofuel is a drop-in substitute for No. 5 and No. 6 fuel oil, or Bunker C fuel.

Greasezilla’s entire FOG separation process is powered by the same rich brown grease harvested, making it an economically and environmentally sustainable system. Five percent of the biofuel produced by the Greasezilla is required to run the system, leaving 95% available for resale in the commodities marketplace. Not only does the system provide a solution for grease trap waste, but it also reclaims a fuel that burns much cleaner than fossil fuels.

Greasezilla allows publicly owned treatment works (POTWs) to accept grease trap waste from haulers, encouraging grease trap maintenance, generating tipping fees and lowering costs for haulers. Separating FOG upstream of wastewater treatment facilities complies with pretreatment standards for POTWs. These measures strive to prevent pollutants from causing obstructions and other operational interference in POTWs.

Utilities of the future

There has been a transformation in the way traditional wastewater utilities view themselves and manage their operations. They are starting to move beyond mere compliance and to consider innovative approaches that focus on efficiency, sustainability, best practices and resource recovery. A growing number of municipalities are incorporating technologies like Greasezilla into their wastewater management processes.

At one wastewater treatment facility, the system processes up to 152,000 litres of grease trap waste per day and is scalable to handle larger flows should the plant be expanded. Including a process like Greasezilla that converts a nuisance waste, like grease, into a commodity grade product appeals to wastewater treatment facilities as it is cost-effective and ecologically friendly. It helps facilities offset a portion of operational costs, while reclaiming a carbon neutral fuel source that can reduce consumption of fossil fuels.

The greatest advantage of hydronic thermal separation technology is that it extends beyond POTWs. Any sites that collect or generate high volumes of FOG, from waste haulers to large food processors, can reap the same benefits of the system. Changing FOG processing from a problem into a global solution will ultimately help our communities, our municipal infrastructures, public health and the environment.

Brian Levine is with Downey Ridge Environmental. Email:

Read the full article in ES&E Magazine’s June/July issue below.

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