Solid Waste & Recycling

Feature

Chicago MRF

Curbside recycling programs are now well entrenched and widely accepted as diversion mechanisms that help reduce reliance on landfill disposal. Refinements to recycling programs are continually introd...


Curbside recycling programs are now well entrenched and widely accepted as diversion mechanisms that help reduce reliance on landfill disposal. Refinements to recycling programs are continually introduced to drive down system costs, increase overall diversion and satisfy public demands.

Blue bag collection programs — recognized as one successful option for curbside placement of recyclables — continue to build momentum among Canadian municipalities (including over 1.8-million households to date). Edmonton, Alberta is recognized as the largest Canadian urban centre offering this option.

Internationally, several large urban centres that have implemented similar variations of curbside blue bag programs. In the United States these cities include New York, Baltimore, Pittsburgh, Dallas and Chicago.

The City of Chicago — the third largest city in the U.S. — launched its program on December 4, 1995. As cities and towns in Canada investigate opportunities to implement more efficient collection programs, Chicago provides an interesting case study.

While initiating a residential recycling program in the early 1990s, Chicago waste management officials sought a program to process commingled materials from its 750,000 residents. Four sorting centres were erected, with the design, build and operations contract awarded to Waste Management Inc. (WMI) of Chicago, Illinois in 1994. Approximately 400 people work two eight-hour shifts at the Medill Avenue Sorting Center and 34th Street facilities, and a single shift at the North/West and CID (Calumet Industrial District) facilities.

The city pays WMI a $20 per ton processing fee. Current tip fees at the private landfill (Waste Management/ Allied) are $40 per ton. The city only pays a processing fee for 75 per cent of total material tipped at each facility.

Collection

Once per week, the Chicago Department of Streets and Sanitation collects recyclable material with residential municipal solid waste. Recyclables are separated into fibre (mixed paper) and container streams, collected in two separate see-through blue plastic bags. All blue bags are placed in wheeled carts for collection. The city has purchased the carts from two vendors, Chicago-based Cascade Engineering and Toter, Inc.

Yard organics are also collected in see-through blue bags. The bags are purchased directly by residents at retail outlets, and the city provides the wheeled carts. Blue bags are placed in the same containers as residential waste.

Specific materials collected in the paper mix include: old newspaper (ONP), old corrugated containers (OCC), magazines, ad mail and other non-contaminated paper products. Although the program does not accept packaging, the commingled container mix includes the following: aluminum and steel cans; aerosol cans; aluminum foil; clear, brown and green glass; PET and HDPE containers.

Each recycling centre is separated into four main divisions: the tip-floor, processing area, end-waste transfer area and recovered material storage. Upon entry to the sorting area, commingled blue-bag recyclables, yard material and solid waste are tipped onto the concrete tipping floor. The materials are then transferred to the first of eight sorting stations:

Station #1: Non-recyclable bulk material is manually removed from the mixed waste stream and transported via by-pass to the end-waste area. Blue-bagged yard waste is also separated from the mixed waste stream. Bags are manually separated from organic material by staff from Chicago-based Remedial Environmental Management. Yard waste is bulked and transported to a regional composting operator.

Station #2: Bagged fibre (paper) material is removed via Mayfram and Hussler conveyors to a quality control station where the bags are manually removed along with any contamination.

Station #3: Material is transferred to the paper sort station where it is manually separated by grade.

Station #4: Following the removal of bags filled with mixed paper and yard waste at the primary sort, the blue bags of mixed containers are removed from the main conveyor belt and transferred to a quality-control station. Here the bags are removed along with any large visible contaminants using a Mayfram de-bagger and the mixed container stream passes through the Dings and Eriez magnetic separators, which remove ferrous.

Station #5: The mixed container stream then passes through an air classifier system that separates out the light fraction. Heavy-fraction glass is transferred to a separate sorting station where it is manually sorted by colour.

Station #6: The remaining light fraction — aluminum and plastic containers — is transferred to a workstation where it is sorted by grade.

Station #7: Recyclable material is extracted from the incoming mixed waste stream. This “non-blue bag” material is run through a 40-foot McLanahan trommel and 3/8-inch Powerscreen trommel screen to separate the material into two different sizes: <2 inches and <9 inches (or 5 to 23 centimetres).

Station #8: After passing though a large rotating drum that removes recyclable materials, mixed solid waste between 2 and 9 inches passes through Dings and Eriez magnetic separators where recyclable ferrous materials are removed, and then to a solid waste sort station for further separation or disposal. Materials over one metre are transferred to a secondary sort area where fibre products not in bags are processed.

All the recovered recyclables are sent to end markets that enjoy proprietary relationships with WMI. The company is responsible for marketing all these materials. Approximately 900 tonnes of material per day is processed at each of the Medill and 34th Street facilities, and approximately 1,360 tonnes per day is processed at each of the N/W and C/D facilities. Overall diversion for 2000, including commercial and construction waste material, was 48 per cent; the residential diversion rate was 26 per cent.

Connie Vitello is editor of this magazine.

Diversion Rate (Jan. – Dec. 2000) Tons of Material
Aluminum 2,223.36
Blue Bags 128.96
Concrete 991.82
Steel/Miscellaneous Metals 29,591.34
Glass 4,524.64
Paper 57,863.23
Plastics 785.64
Wood 29,483.37
Yard waste 170,770.20
Total Blue Bag Commodities 296,362.55
Total Diversion Rate 26.4%
Source: City of Chicago web site.

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