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[GreenYes] Re: [GAIA] Info request: organics treatment in big cities

Hi Cecilia,

Toronto has a great program. Yard trimmings are composted. Food scraps (along with diapers, pet waste, kitty litter, tissues/paper towels) are collected separately each week and anaerobically digested. The city cut back trash collection to once every other week. This has greatly increased participation in the organics collection program (which is 95% on a monthly basis). The City has a 70% diversion goal and is at 42% citywide currently.  Single-family households have reached above 60% diversion (510,000 single-family households).  Toronto is Canada's largest city and has 2.6 million people. The program serves 1 million. The City cites 3 Bs of success:  Bins, Bags, and Biweekly trash collection. Regarding the bags, the city allows residents to put their food scraps in regular polyethylene plastic bags.  Regarding Bins, the city provides two bins for the organics collection, green 45 liter bin, which is set out at the curb, as well as a smaller bin for use in the kitchen.  This bin was specially designed for the program (to facilitate dish scraping for instance) and can be wall mounted if desired (but easily removed for use). 

The digester used currently was originally designed to handle 25,000 metric tons per year but handles 40,000.  It cost $10 million but only flares the methane.  The city is in the process of building two more, each at $22 million and with capacities of 55,000 tons per year. These new digesters will recover the methane for energy.  Currently there are 4 stages to the anaerobic digestion system:  (1) centrifugal removal of gross contaminants and plastic bags with hydropulpers, (2) anaerobic digestion of material in 8 to 10 days, (3) screw press digestate to solid form, (4) final finishing of digestate at windrow site with leaf and other yard trimmings.

The city is still rolling out this program.  Starting Nov. 1st, it will be targeting multi-family dwellings.  Starting Nov. 1st the city will begin paying for the program by  becoming a Solid Waste Utiliy and using pay-as-you-throw fees rather than through the previous tax base.  23% of homes have signed up for the small trash bin, 8% for the large one, and the rest for the medium size.  Grass clippings, by the way, are not permitted in the yard waste program.  Residents must grasscycle and the city offers mulching mowers at a subsidized rate.


Brenda Platt
Institute for Local Self-Reliance
927 15th Street, NW, 4th Fl
Washington, DC  20005
202-898-1610 ext. 230

On Thu, Oct 9, 2008 at 11:51 AM, Cecilia Allen <cecilia@no.address> wrote:
Hi all,

We´re looking for experiences of treatment of organic municipal solid waste in big cities, as part of our efforts to make Buenos Aires city start treating its organic waste as a key implementation of its ZW law. Do you know of big cities that are treating the organic fraction of their MSW through compost or anaerobic digestion? Or do you know of good compost or anaerobic digestion plants in your countries that are treating a big amount of source segregated organics? We have info on San Francisco already, and we are looking for other examples.  We are suggesting strategies at different scales, and we lack information on plants with high treatment capacity.

Thank you in advance,


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