Single-stream (also known as “fully commingled” or "single-sort") recycling refers to a system in which all paper fibers, plastics, metals, and other containers are mixed in a collection truck, instead of being sorted by the depositor into separate commodities (newspaper, paperboard, corrugated fiberboard, plastic, glass, etc.) and handled separately throughout the collection process. In single-stream, both the collection and processing systems are designed to handle this fully commingled mixture of recyclables, with materials being separated for reuse at a materials recovery facility (MRF).
Single-stream recycling programs were first developed in several California communities in the 1990s. Subsequently, many large and small municipalities across the United States began single-stream programs. As of 2012, there are 248 MRFs operating in the U.S.
Proponents of single-stream note several advantages:
Reduced sorting effort by residents may mean more recyclables are placed at the curb and more residents may participate in recycling;
Reduced collection costs because single-compartment trucks are cheaper to purchase and operate, collection can be automated, and collection routes can be serviced more efficiently;
Greater fleet flexibility, which allows single-compartment vehicles to be used to collect recycling, providing greater fleet flexibility and reducing the number of reserve vehicles needed. To avoid confusing customers, a large sign or banner is sometimes used to distinguish when a refuse truck is being used to collect recycling (instead of refuse).
Worker injuries may decrease because the switch to single-stream is often accompanied by a switch from bins to cart-based collection.
Changing to single-stream may provide an opportunity to update the collection and processing system and to add new materials to the list of recyclables accepted; and
More paper grades may be collected, including junk mail, telephone books and mixed residential paper.
Potential disadvantages of single-stream recycling may include:
Initial capital cost for:
New carts
Different collection vehicles
Upgrading the processing facility
Processing costs may increase compared to multiple stream systems
Possible reduced commodity prices due to contamination of paper or plastic
Increased downcycling of paper, i.e., use of high quality fibers for low-end uses like boxboard because of presence of contaminants;
Possible increase in residual rates after processing (chiefly because of increased breakage of glass)
Potential for diminished public confidence if more recyclables are destined for landfill disposal because of contamination or inability to market materials.
