FOG and the circular economy

There is a great potential to pivot FOG from a pollutant to a waste resource material, but more awareness must be raised to enable this circular economy.
Circular economy
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The UK has around 360,000 food businesses, each producing tonnes of fats, oils and grease (FOG) waste every year. In the current landscape, not all food businesses have appropriate and well maintained grease control devices in place, therefore many are inattentively letting these pollutants enter the sewers.

The result is shocking, with an estimated 250,000 tonnes of FOG blocking sewers every year. It’s an incredible amount of waste that could be recovered as a valuable resource for circular economy initiatives, but instead, brings disruption and preventable pollution. 

There are nearly 366,000 sewer blockages happening in the UK annually, 70% of which are caused by FOG. Cleaning and repairing this pollution costs water companies a recorded £90 million so it’s safe to say that the situation would be a lot different if FOG simply didn’t enter the sewers in the first place.

A viable circular economy

The recycling model for used cooking oil (also known as yellow grease) demonstrates a well recognised circular model for a waste resource that shares a lot of similarities with FOG (or brown grease).

Whilst not every food service establishment (FSE) produces yellow grease in quantities, most do produce the brown one. Still, despite its widespread production, the UK doesn’t have a common system that stimulates the storage, collection and recycling of this material, unlike yellow grease.

If converted to biodiesel, those 250,000 tonnes of FOG would help the UK to prevent 1 million tonnes of greenhouse emissions due to the reduction in virgin diesel use, the equivalent to 1.2% of the yearly domestic diesel consumption for road use. Moreover, FOG has a carbon footprint 90% lower than traditional diesel

From waste to resource

The most common option for capturing FOG occurs with the help of grease traps installed in commercial kitchens. These devices are placed at strategic discharge points of preparation and cleaning operations. They separate fat from wastewater, capturing FOG at source and preventing FOG from entering the sewers. The waste is collected by licensed service providers, onwards for recycling.

While it is not impossible to retrieve FOG from sewer blockages, this is not optimal, or the most efficient approach to feed a sustainable circular economy. “You’ve got a decreasing energy content as you move away from the source,” said Dr Raffaella Villa, from De Montfort University, in an episode of the Fatberg Forum Series.

“If you recover [FOG] at the source with a grease trap, you’ve got cleaner material with a higher energy content and fewer problems in the sewers, but if you leave it, obviously what you recover in the sewers is dirty, it’s contaminated and it’s got a lower calorific value.”

One major challenge is the process for adequate storage and collection procedures. In the current scenario, bioenergy companies struggle to create this green conversion due to a lack of feedstock and must look to alternative options. 

“A lot depends on the scenario: who’s collecting it, who has ownership of the material at that stage,” says Dr Tom Curran, from the University College in Dublin. “It really depends on the city and the country where you are, what are the options and the facilities available that you can transport it to, that makes it a viable option.”

There is a great potential to pivot FOG from a pollutant to a waste resource material, but more awareness must be raised to enable this circular economy. FOG holds an exciting opportunity to create positive change both economically and sustainably, but most importantly, to protect and safeguard the future of our environment.

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