In the course of our daily reporting, we often uncover unusual projects, places, or connections that don't make the final cut. Instead of keeping it to ourselves, we're pleased to share our Architrivia.

Edmonton's most famous sprawling facility is probably the West Edmonton Mall, which was once the world's largest shopping centre and remains the biggest in North America. But an entirely different facility — off limits to the public— fulfills an integral job at a similarly massive scale. Occupying 38,690 square metres, an area equivalent to eight football fields, the Edmonton Composting Facility at the Edmonton Waste Management Centre is the largest co-composter in North America by volume and capacity.

The Edmonton Waste Management Centre, image retrieved from Google Maps

The enormous facility composts residential solid waste with sewage biosolids from the city's wastewater treatment plant. Queues of garbage trucks unload the collected solid waste onto a large indoor concrete pad called the tipping floor. Heavy machinery transfers the waste onto conveyor belts where non-compostable and oversized items are manually removed. Trommel screens then allow compostable materials to fall through the holes, while objects that are caught are sent to the landfill. From there, de-watered biosolids are injected into 74-metre-long mixing drums with the waste. 

The largest stainless steel building in North America, image via City of Edmonton

Two additional rotating trommel screens remove larger non-biodegradable materials before compostable material travels to the aeration building, which at the size of 14 NHL rinks, is the largest stainless steel building on the continent. The material is laid in three aeration bays for two to three weeks, where it is exposed to temperatures in excess of 55 degrees Celsius to kill potentially harmful bacteria. A series of biofilters removes any unpleasant odours as the compost is sent through another screening process. Finally, the compost is cured over four to six months on an outdoor curing pad, readying it for use by farmers, nurseries, and oilfield reclamation companies. 

The Waste-to-Biofuels and Chemicals Facility, image via City of Edmonton

The facility creates compost from 160,000 tonnes of organic waste and biosolids every year. Much of Edmonton's non-compostable and non-recyclable material is sent to the state-of-the-art Waste-to-Biofuels and Chemicals Facility, the world's first industrial-scale facility to produce biofuels from household garbage. As of 2014, the City of Edmonton diverted approximately 60 percent of residential waste from landfills through its recycling and composting programs. That number is expected to jump to 90 percent this year with these two facilities working in conjunction.