Toronto's green bin program means less waste, more composting.
The hydropulper is like a giant blender, gently agitating compost from your green bin. The light stuff, such as plastics, go to the top where it is skimmed off and sent to landfill, while the heavy items go to the bottom where the process continues.
Photo Courtesy/CITY OF TORONTO
Toronto's green bin program was launched in 2002 and now diverts just more than 100,000 tonnes of material each year, yet despite its success, people still doubt composting is actually worth doing.
Geoff Rathbone, general manager of solid waste services for the City of Toronto, said there are many myths and questions when it comes to the green bin program, one of which is the inconvenience of putting food waste in a separate container, which may attract wildlife.
But Rathbone said food waste already existed, just in the garbage bin.
"It's not as if we're creating new organic material, it's simply going into a different container," he said.
Another popular argument is neither recyclables or green bin waste are being separated and reused accordingly.
"It's a real urban myth," said Rathbone, who began his career in waste management 20 years ago. "Like many things...occasionally (we) have an unscrupulous contractor or operator, but I can absolutely assure you, particularly in recycling, that everything gets used."
One of the questions people have is what can actually go into the green bin.
The simple answer, Rathbone said, is all food products, no exceptions, as well the paper containers they come in, such as pizza boxes, can go in the green bin. However, some food containers should be recycled.
"Our first choice is always to recycle, so if I take a pizza box, in most cases unless it's severely food contaminated we can recycle it and that's a better way to go than to put the pizza box into the green bin," he said.
"So they get one more life before they have to become compost," he said.
Some of the confusion about the green bin may also derive from the fact there are different rules for the City of Toronto verses other regions. Durham is different than Toronto, which is different than Peel, Rathbone said. Each region is independent in terms of processing material.
For example, Rathbone said Durham Region has massive rural areas for their compost site, which Toronto doesn't.
"Steeles Avenue is our northern boundary so we simply could not, and none would want us to, build an outdoor compost site here," he said. "We don't have a lot of large, open spaces here in Toronto suitable for outdoor composting but we do have seven transfer stations and those we determined were suitable..." he said.
Because of these indoor spaces, Rathbone said Toronto is the only Ontario jurisdiction that uses anaerobic digestion process, anaerobic meaning composting in the absence of oxygen.
"Certain kinds of bugs and microbes live where there's oxygen and other types live where there's no oxygen," he said. "The analogy I like to use is the sewage from your house gets treated by Toronto water at our sewage treatment plant and they also use an anaerobic digestion process."
All the other regions use the opposite of anaerobic, which is aerobic, which means composting with oxygen.
"So they use a different system of composting that really relies on a large outdoor space, but in our anaerobic digestion system the technology utilizes water as well," he said.
This translates into Toronto's system being able to handle more items than many other green bin programs.
Rathbone said this process is one of the reasons why Torontonians are allowed to use plastic bags and liners and people are able to put in things such as diapers, kitty litter and animal waste in their green bins.
"Our process is more similar to a sewage treatment process so you can therefore see why we don't have any difficulty managing diapers or animal waste... with the anaerobic process it provides the pathogen kill similar to a sewage treatment plant," he said.
If you use disposable diapers, you may be aware of the concerns of human waste leaking into the soil and into our water system. Rathbone said this is another benefit of anaerobic digestion.
"We basically are treating the human and animal waste and not allowing it to go landfill because we're treating and creating useful product from it," Rathbone said.
To separate the green bin matter, they use a hydro-pulper, which essentially is a giant blender that gently breaks the bags and the diapers open. Like a blender, Rathbone said if you put something light in it, it'll gradually float to the top while the heavy things go to the bottom.
"That's exactly what happens in our giant blender, all the light fraction, the plastic bags, the liners off the diaper, comes up and we skim that off and that goes to landfill," he said.
When you have a million customers, you have to plan for some mistakes, but because of this process "mistakes" are easily separated and skimmed. For example, someone's packaged meat goes bad and they don't remove it from the packaging before tossing it into the green bin.
"We don't want plastics so that's why in this hydropulper, we don't pulverize the plastic into thousands of little pieces, it would gently agitate that package until it opens, allow the meat to fall out and then the plastic floats to the top," he said.
Once it's skimmed, the leftover flurry goes into the 3.5 million-litre digestion tanks where the bugs live and eat the material producing a methane and a solid or digestate. Once the solids become a digestate, they go off for final composting at a transfer station. The entire process - from pick up to compost - takes about a year.
While it is an expensive and long process, Rathbone said programs exist to divert waste from the landfill and it's succeeding.
"Every year we hope to move a little closer to that zero-waste vision," he said.