The London Greenway Pollution Control Centre (“Greenway” for short) is the main wastewater treatment facility for the city of London, Ontario. Greenway is an activated sludge plant that also receives liquid sludge trucked in from the city’s other five wastewater plants.
Greenway dewaters the sludge and relies on a fluid bed incinerator. In 2008, the incinerator required shutdown for major overhaul that would last over three months. The city’s Wastewater and Solid Waste departments are separate entities and are required to charge each other for services rendered. After determining that a prolonged incinerator shutdown would have a prohibitive cost, the Wastewater Department sought alternatives.
Schwing Bioset piston pumps were previously installed at the Greenway plant to feed the dewatered sludge to the incinerator, so plant personnel were knowledgeable about Schwing Bioset capabilities. The Bioset process was proposed to treat the dewatered sludge to beneficially reuse the biosolids as landfill cover. Representatives from the Wastewater and Solid Waste departments visited Bioset installations in Florida to observe the process and it was determined the end product would be acceptable as landfill cover at a preferable cost.
A change order was issued to the incinerator rehabilitation contractor to install the Bioset process equipment as a back-up sludge treatment train to the incinerator. The component equipment permits flexibility in the layout design that allowed the plant to use distinct idle spaces so that no new structures were needed to accommodate the installation.
The plant processed 25,000 metric tons of Bioset product between August and December 2008 while incinerator rehabilitation work was completed. The city has since returned to incinerating the biosolids, but maintains the Bioset equipment as a back-up for annual shut-down/rehabilitation work.