Why are recyclables from dirty materials recovery facilities often contaminated?

Recyclables recovered from "dirty" materials recovery facilities (MRFs) are often contaminated because these facilities process the entire municipal solid waste stream rather than relying on residents or businesses to separate recyclables at the source.1

Because a dirty MRF handles a mixture of all waste types, the recovered materials frequently suffer from contamination caused by contact with moist garbage and broken glass. Unlike "clean" facilities, which receive pre-sorted materials and maintain higher purity levels, dirty facilities must use manual and mechanical sorting to extract recyclables from a broad, unseparated waste stream. This process is inherently less effective at preventing cross-contamination between recyclable goods and nonrecyclable refuse.12