Super Sized in Seattle

MRF in the Emerald City is revamped to handle more recyclables and single-stream collection.

Seattle is known for many things: super-strong coffee, grunge rock, the Space Needle, endless rain and “Grey's Anatomy.” Frankly, this probably doesn't draw many tourists, but the city is also the location of the largest material recovery facility (MRF) west of the Mississippi River.

For nearly 80 years, the site in South Seattle operated as a major steelmaking mill under the management of U.S. Steel Corporation and produced steel to order for both the domestic and international markets. In 1989, Rabanco Cos. (now a Republic Services company) converted the mill into a state-of-the-art recycling facility. After its reclamation for recycling, the plant grew over the years, eventually processing approximately 15,000 tons of recycled material each month. As Allied Waste (which owned Rabanco and merged with Republic last year) took on new recycling contracts with the city of Seattle, the company invested in additional upgrades. The site continues to process 100 percent of the recyclable materials collected from Seattle residents.

In 2008, the facility underwent a major overhaul, which was designed to increase the ease of recycling for Seattle residents. Allied's $9 million investment in the 11-acre plant allowed Seattle residents to put paper, cardboard, metal, glass and plastics in the same recycling container for the first time. The facility was one of the first commingled MRFs in the United States back in 1989 and is now leading the way in single-stream processing capabilities. The MRF is now 100 percent single-stream, processing more than 17,000 tons of materials per month. Even with that tremendous volume, it achieves a huge diversion rate — approximately 96 percent.

The facility actually recycles materials beyond traditional metal, glass and plastic. For example, in conjunction with Seattle, it accepts residential waste oil and small scrap metal collected at the curb.

The upgraded “super” MRF combines high-tech equipment and traditional sorting methods to process the materials that come in into the cleanest end products possible. In addition to the high-tech advances at the MRF, there are still more than 30 sorters on the line separating materials and ensuring quality control.

Loads are placed on the tipping floor and crisscross more than 2,000 feet of conveyors, belts and screens. When all is said and done, the loads are separated into nine separate recyclable commodities. Allied contributed to the design of a new processing system for paper, cardboard and newspaper, as well as a new system for aluminum, tin, steel and plastic containers. These changes resulted in greater processing and capture efficiency, and less residual waste.

For processing plastics, an advanced optical scanning system reads and identifies the grade of the plastic (polymer), and blows it off of the sorting line via a strong burst of air (a process known as high precision air classification). This series of optical scanners is high speed and high volume, and exceeds the capture possible with human hands. While there has been no change in the inbound volume of plastics, the state-of-the-art scanners have identified and sorted more plastic, doubling the quantity of most resin grades, and yielding a higher quality finished product.

The MRF also uses one of the most advanced glass processing systems in the nation. It permits plastic, paper and glass to be in the same waste stream rather than being separated. Through use of a negative air aspirator and a series of shaker screens, light fraction paper and plastic is separated from mixed glass, producing clean cullet.

Allied is a primary processor of recyclables, and a major focus of its South Seattle MRF is creating and finding markets for recycled materials. Some of the facility's marketed grades are produced specifically for secondary processors, a process sometimes referred to as benefication.

The site is ideally situated in the heavy industrial district of South Seattle, also known as SODO, just minutes from major highways, on a Class I rail spur, and five minutes from the Port of Seattle. Getting these products out to end use markets is an important part of closing the recycling loop.

A well-run MRF means better recycling opportunities for communities and more items kept in the manufacturing loop. In the end, that translates to fewer tons of waste in the landfill, fewer raw materials needed to create new products, and far less energy consumption, resulting in less overall greenhouse gas emissions.

Pete Keller is general manager of Washington state post collection operations for Republic Services.

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