Published: June 1, 2017

Recycling at the Field

Carter O'Brien, Sustainability Officer, Keller Science Action Center


Perhaps you’ve noticed the blue recycling carts around The Field Museum, the customized recycling bins in the Field Bistro, Explorer Café and the Siragusa Center, and if you are here on Members' Nights, a variety of other recycling containers in the halls behind the scenes. If so, we hope you’ve found them easy to use! The Field Museum diverted 53% of its waste from landfills in 2016, with 31 tons of that amount being captured in the blue carts.

But what happens to those materials after they leave the Museum? Do they really get recycled into new products? On April 6, 2017, sustainability manager Carter O’Brien and volunteer Emily Woodworth took a tour of Lakeshore’s Heartland Recycling Center to find out. 

Opened with new state-of-the-art machinery in the spring of 2016, this single-stream facility sorts, separates, and allocates over 2.3 million tons of waste material annually. Materials including paper, cardboard, glass, plastic, and metal are accepted, with the facility able to process 20 tons per hour.    

When materials arrive at the facility, they come mixed together and are dumped in a large pile that looks similar to traditional garbage. In order to be sold for remanufacturing, they need to be sorted by material. The process begins when a claw excavator collects small bundles from a mound along the back wall, dumps the materials onto a conveyer belt, and passes them under the back scraping drum, a large notched cylinder which turns on a horizontal axis and courses the material into a steady, even flow to the pre-sort line.

Here, Lakeshore’s sorting personnel pull any items that would interfere with the machinery processes. Oversized plastic items (such as milk crates and laundry baskets), wood and rubber are removed by hand and deposited into sorting columns below, where they are redistributed to proper recycling channels or landfill. 

One of the early stops in the automated process is the Fines Screen. Here, glass and all fine materials that are less than two inches in size are removed. Glass passes through the Glass CleanUp System, which cleans the glass coming off the Fines Screen by pulling off all the light fractions such as shredded paper. Glass is then sold to a local manufacturer, who in turn sorts it by color before using it as a raw material for new products. 

The next type of material to be removed from the stream is cardboard. The OCC Screen (aka old corrugated containers) removes all of the larger cardboard pieces directly from the sorting process. Once removed, they are sent to the American Baler where they are bundled into compact cubes for easy transport. 

Paper fiber is separated from glass, plastic, and metal in a two-step process. First, the News Screen uses a pitched series of rollers to tumble these materials. Heavier items succumb to gravity and fall to the bottom and continue their journey through the system for further sorting. Newspaper goes over the top into another collection receptacle. The second stage of this process is the Ballistic Separator. Materials that fell to the bottom in the last stage are sorted again, with a series of sloped paddles, into 2D (paper, plastic film, cardboard, fibers) and 3D (bottles and cans). As before, heavier 3D items bounce or roll downward, and lighter 2D items travel up the slope in the direction of the paddles. Plastic film is removed at this stage and sent to the Machinex Closed Door Baler.   

Metals are pulled from the stream using two different methods. First, The Ferrous Magnet, which is located over the top of the belt, pulls out all ferrous metal, including steel and tin. The magnet is so strong that it can detect these metals even if they have labels still attached. As aluminum and some other metals are non-ferrous, sorting this material requires the use of an Eddy Current Separator. Electromagnetic fields are created by a series of magnets that spin fast and eject all non-ferrous materials by pushing them out of the stream.   

Plastics are separated using an Optical Sorter. This is designed to optically scan the materials and generates a puff of air onto any plastics it deems to be PET (plastics marked #1).

Separated commodities are stored in holding bins before being sent to the Machinex II-Ram Baler.  A computerized system allows the baler to be calibrated for which type of material is passing through. The baler will run through one type of commodity at a time, as it is crushed down into dense cubes and tied into a bale with thick wire. The machine pushes out tidy cubes ready for transport.  As mentioned before, cardboard and plastic film are the only two commodities that pass through balers specifically designed for that type of material. 

After all is sorted, baled, and stacked for distribution, what remains is a small pile of garbage. But even this pile will pass through the system a second time to assure that all possible recyclables are destined for reuse and not the landfill. 

Finally, recycling is not just good for the environment. It also can contribute positively to our local economy. Lakeshore works with a variety of local manufacturers to find the best use for these raw materials, with blue cart recycling being used to make everything from paper and cardboard products to bicycle frames to playground equipment.