Material Matters: Definitions of Terms

These are definitions of terms used in the dashboard.

Recycling is the process of converting waste into a form in which can be re-used in the making of another product. In Material Matters data reporting, “recycling” refers to the material collected in blue bins across campus that includes mixed plastics, glass, metals, cardboard, and papers. These mixed materials are  transported to a materials recovery facility in Charleston where it is sorted and sold to manufacturers as a commodity for industry. MIT waste audits reveal that recycling streams are often contaminated. Fortunately, the materials recovery facility process includes contamination removal, which safeguards MIT’s valuable recycling and ensures its resale for use in new products.

C & D stands for construction and demolition [debris] which includes material such as furniture, building materials, large household goods, wires, etc. that is collected and removed from small campus renovations, repair, maintenance, and move-out activities. C &D is transferred from campus to a facility that sorts through the material and separates out material for recycling.

Contamination is when material is placed into the incorrect waste stream, such as  plastic wrap or food waste deposited into recycling, or food containers deposited into food waste only bins. Contamination may additionally occur when materials contain too much food residue and fall into the “yuck” category (things that downgrade other materials and clog the system such as food, liquids, diapers, etc.).

Diversion is the process of diverting waste from disposal in landfills or incineration through recycling, re-use and food waste collection and processing.

Diversion rates measure the portion of waste not sent to the landfill or incineration. Tracking diversion rate over time is a conventional measure of the effectiveness of waste the reduction of waste generation, recycling, and food waste collection and processing.  For MIT, diversion includes mixed recycling, food waste, yard waste, hard-to-recycle items, and other diversion (blue line plotted against the right axis). 

Food waste is an MIT waste stream category that only includes scraps and spoiled food. collected from about 20 locations on campus and processed off-campus via anaerobic digestion; converting the food waste into energy. During prior years, this stream was called "Compost" and included paper plates, utensils and containers which were processed on farms. The largest generators of campus food waste are kitchens from dining operations. 

Hard-to-recycle items include clothing, tires, mattresses, books, e-waste, and metal, which are collected in designated bins on campus. MIT engages different specialty recyclers for hauling each stream away from campus and processing and re-selling into the recycling marketplace.  

Yard waste (grass clippings, woody materials, leaves) are collected on campus by Grounds Services and transported by a contracted waste hauler to several Massachusetts farm and open air composting facilities. Much of the yard waste is re-processed into nutrient-rich loam.

Other: Miscellaneous diverted waste items from the MIT campus, including used research materials and other items that are not easily categorized.