Go Green Pronto, Toronto
Toronto is implementing residential source-separated organics to divert tons of organic matter-about 30 percent of all household trash-from landfills. Currently some of the material is being composted and turned into green fertilizer. Once its plans to construct two large anaerobic digestion facilities are fulfilled, the city will be making green energy to help offset the cost of implementing its green bin program.
Approximately 20 years later, the city of Toronto embarked on an equally ambitious task to steer tons of organic material-table scraps from last night's dinner, banana peels, soiled diapers, etc.-from occupying precious and fleeting space in landfills. This was called the green bin program. According to the city, organics comprise approximately 30 percent of household garbage. Redirecting that large chunk of household trash from the landfill is part of Toronto's goal to reach 70 percent landfill diversion. When achieved, more than two-thirds of all trash generated by Toronto residents will never even see a landfill. "The environment is the primary driver of our behavior, but the second motivator is the limited capacity at our garbage dumps," says Toronto Councilor Glenn De Baeremaeker. "We spent about $230 million of taxpayer money to buy one garbage dump, and once it's filled we don't have another one, so we want to make sure we extend the useful life of that garbage dump because that saves us a lot of money, and political heartache and headache. Nobody wants another garbage dump, and we really can't build another one in our own city, which means we'd be un-neighborly, dumping our trash in someone else's back yard."
Michigan residents are all too familiar with this, as Ontario has found it cheaper to dump its trash in Michigan instead of in its own province. "There has been a lot of fuss from Michigan," De Baeremaeker says. "People don't want imported garbage coming to their community-and that's fair." He says Michigan nets out ahead in the deal though, because while it accepts Ontario's trash, Ontario takes in Michigan's toxic waste. "We should all take care of our own waste-treat it in your own backyard-and with an organics plant we have that option," he says.
Feedstock Collection: The Green Bin Program
When Toronto's green bin program officially launched more than six years ago, no one thought it would become an instant success story with 510,000 single-family homes. "We couldn't stop people from using the green bins even when we said ‘don't use them yet,'" De Baeremaeker says. Green bins were delivered to houses on June 1, 2002, but the residents were asked not to use them yet because the first pickup wouldn't be until July 1. People began to source separate their organics immediately, and after nearly a month of material accumulating in these bins, drivers collecting the bins were getting sick from all of the decomposing material. "So that's the type of insane success we've had in the city of Toronto," De Baeremaeker says. "People thought it was an ecological crime to throw the fish they had last night into the garbage. We don't have organic green bin police searching up and down alleys seeing if people are using their bins. So with virtually no enforcement and very little public education, we had about a 95 percent compliance rate from the very first day."
The launch of the green bin program in 2002 dovetailed with the startup of a 25,000 metric ton (approximately 27,500 ton) per year front-end demonstration facility at the city's Dufferin Transfer Station, built to prove out anaerobic digestion and the BTA process for which Canada Composting Inc. holds a technology license. De Baeremaeker says anaerobic digestion isn't a new technology-but it is new to the general public. The Dufferin biogas demonstration plant doesn't actually produce electricity from the methane gas generated. "No one knew if the technology would work," the councilor says. "So we didn't invest the money to make energy from it." The city has four other sites where organics from single-family homes are delivered and composted, and turned into organic fertilizer.
In November, Toronto announced that it was expanding the green bin program to include another half-million Toronto citizens who were previously excluded from the program, including residents of multiunit buildings, apartments and condominiums. Once all 4,500 multiunit buildings come onboard, the city will be swimming in an additional 30,000 metric tons (approximately 33,100 tons) of organic material in need of a home. Much like the dovetailing of the green bin program in 2002 with the startup of the Dufferin demonstration plant, once all the apartments in Toronto are in the program, the city says it will include 300 additional buildings per month over the next 18 months. When all the apartments are incorporated in the green bin program, the city hopes to have made significant headway on construction of the first of two 55,000 metric ton (approximately 60,600 ton) per year anaerobic digestion facilities.
Dufferin Demonstration Plant
The demonstration plant at the Dufferin Transfer Station was designed to prove out a wet preprocessing stage and anaerobic digestion, and process 25,000 metric tons (approximately 27,500 tons) per year, however, plant manager Doug Beattie tells Biomass Magazine the facility has been operating well over capacity, taking in more than 40,000 metric tons (approximately 44,100 tons) per year. Beattie says moving from two shifts per day to three has, in part, helped achieve operation well beyond design capacity.
Randy Cluff, a board member and consultant with Canada Composting Inc., says in 1999, Toronto decided to develop a demonstration project to figure out how to divert organics from the waste stream. A request for proposal was issued, attracting 19 bidders. The city selected CCI's technology proposal. "So off the project went," Cluff says. "It was developed in 2000, all done under demonstration basis-they wanted to see how the technologies performed so after a couple of years they could formalize a larger plan." Cluff says CCI is the license holder for BTA technology in the United States and Canada.
Beattie says the technology was developed by a group of engineers-half in the pulp and paper industry and the other half in wastewater treatment. "Some of them were familiar with pulpers used to pulp paper and thought it was an ideal system to pulp up food waste and mix it with water," he says. "The engineers with wastewater treatment were familiar with anaerobic digestion." The two processes were linked together, creating the BTA process.
The differentiated front-end technology at the Dufferin plant is designed to clean the contamination from the organics to produce a high-quality organic pulp. This pretreatment is an important step, as Cluff says contamination in the feedstock can be as high as 12 percent by weight. "Even in source separation you're going to get contamination," he says. "Forks, knives, household batteries, tin cans, Pepsi bottles, anything you can think of." And plastic, lots of plastic. Residents line their "kitchen catchers," small pails used for organics in the home, with plastic bags so when it's full there is little mess and they can tie it off and take it to the green bin, which may also be lined with plastic. "Toronto allows people to collect their food wastes in plastic bags because [before the Dufferin demo plant was built] the city was concerned whether the equipment could remove the plastic bags, so the pulper was installed to do that side of the work," Beattie says. "Basically the pulper is a big mixing tank that's filled half full of water, and the rest is food waste that's conveyed in with a big conveyor, then a mixer grinds up the food waste into a soup-like mixture, which is pumped out to a great big tank-the digester-where bacteria breaks this organic matter down and produces methane gas." Once the digester, which has a 3,600 metric ton (approximately 3,970 tons) capacity and a 12- to 14-day residence time, breaks down the material, the remaining solid/liquid mixture is dewatered and the solids are then shipped out for composting, according to Beattie. "The technology is all quite simple," he says. "There are mixers, pumps and conveyors-nothing rocket science about it."
Because CCI is the technology provider for the Dufferin demonstration plant, it is one of two bidders hoping to land the contract with Toronto to build two 55,000 metric ton (60,600 ton) per year anaerobic digestion facilities.
Economic and Environmental Drivers
It takes fuel, labor, time and equipment-money essentially-for the city to collect tons of trash from all over Toronto on a regular basis. De Baeremaeker says generating methane gas, electricity or even perhaps liquid fuels from digesting the source-separated organics will help offset the cost. "There will be flexibility and flexible thought with respect to the final use of the biogas-it could be used for CHP (combined heat and power), or liquid fuel, or pipeline-grade gas, or any combination of those things," Cluff says.
De Baeremaeker says for the past six years there's been zero incentive for residents to participate in the program other than being good, environmentally conscious citizens. "But we're changing that," he says. "As of Nov. 1, we have gone to a user-pay system where the more garbage you produce, the more you pay. People will now have an additional financial incentive to throw their banana peels in the green bin. Under the new system recycling, green bin organics and yard waste are all collected for free; you only pay for what you put in your garbage can." Now, the 5 percent of Toronto residents living in single-family homes, who haven't been driven by the environmental aspect to recycle their organics, have a financial incentive to do so.
"Obviously what's being done now around the world is not sustainable," De Baeremaeker says. "You can't consume everything and throw it in a dump. If we're going to survive on this planet as a species, we have to make sure it's sustainable. We've all heard about global warming. We see the ice caps melting. We understand polar bears are on their way to being extinct and we don't want to contribute to that. In fact, we want to reverse that process."
Ron Kotrba is a Biomass Magazine senior writer. Reach him at firstname.lastname@example.org or (701) 738-4942.