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London evaluates a novel approach to FOG source diversion

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Grease in pumping station
Thick grease coats the inside of this pumping station.

By Barry Orr, Miranda Gregorio and Roger Gurnett

In 2008, the City of London, Ontario commissioned a fats, oils and grease (FOG) inspection program. While the initial focus had been on restaurants, a surprising number of FOG “hotspots” were also found in residential areas. The City’s “Your Turn” program was created to assist in the proper disposal of residential FOG and to increase public awareness of sewer systems and wastewater treatment.

An opportunity to reach residents at special events was identified. The City’s communications department and wastewater treatment operations set out to custom order a biodegradable take-home container (the “Your Turn” cup) that citizens could use to dispose of residential FOG generated in their kitchens.
An outreach opportunity for the “Your Turn” project was initiated and a letter was sent to the residents in two neighbourhoods, inviting them to participate in this pilot project. Representatives from the City then went door-to-door handing out cups and pamphlets. Most residents were happy that this project was taking place in their neighbourhood and were pleased to help.

A "Your Turn" outreach station at London apartment building.
A “Your Turn” outreach station at London apartment building.

The first project occurred over a period of four months, from November 2013 to January 2014, and was followed by a survey. Results revealed that the project raised awareness, and that the majority of the people who completed the survey used the cups to dispose of their FOG waste. Seventy-eight per cent said that they put the entire kitchen FOG they produced in the cups. Seventy-two per cent said that they learned more about the problems caused by FOG.

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The increased awareness and consistent cup use appear to have decreased the amount of FOG found in the area’s sanitary sewers.

The second project took place from June 2014 to August 2014. Residents were also asked to complete a survey. Results were positive and revealed that 68% of participants said they used the cup every time they generated FOG in their kitchens. Nearly 62% of people disposed of their cups in the garbage. Additionally, 68.2% said that their awareness of the damages of FOG was increased during the project.

Overall, 90% of people reported that they would use a similar cup on a regular basis. However, many respondents indicated that they would not be willing to purchase one. Those who would consider purchasing cups were not interested in paying more than $0.50 per cup.

In addition, residents of the neighbourhood targeted in the second project were given the option to drop off full cups at an “EnviroDepot” about eight kilometres away. Over 90 cups were received and taken to an anaerobic digester for testing and disposal.

Purpose of calculations

Another aspect of the pilot project was to determine whether “Your Turn” cups are financially feasible, and if so, whether they could be implemented on a larger scale.
To do this, the following procedure was employed:

  • Major costs of treating FOG waste in London’s sewage system were identified.
  • Research was performed to determine which (if any) of these costs could be quantified on a $/mass or $/volume basis.
  • Easily quantifiable costs were quantified.
  • Values were converted from a $/tonne basis to a $/cup basis; this value was weighed against the cost of purchasing the cups.

Ultimately, if the per-cup cost of treating FOG was close to or greater than the per-cup price, then the use of “Your Turn” cups would be a reasonable option to pursue in the future.

Major costs of treating FOG

The largest cost of FOG treatment that was determined in this analysis is having the fats, oils and grease, that were skimmed from primary sedimentation tanks, hauled from the wastewater treatment plants (WWTP) to a Green Turtle Proceptor™. This is performed by a company that is contracted by the City. The next largest cost analyzed is having the FOG hauled from the Proceptor to the landfill.

The third cost in this analysis is the cost of sending full “Your Turn” cups to the landfill. The addition of kitchen FOG waste to the solid waste stream represents an additional burden on the municipal solid waste system.

There are two other major costs that could not be included, due to the difficulty of accurately estimating them. These are the costs of WWTP treatment, and cleaning FOG from sewers and pumping stations.

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