In the waste management hierarchy, recycling follows source reduction and reuse. MRFs are an important first step in the recycling process to sort and prepare recyclable materials for alternative uses. There are four main types of MRFs, each of which depends on the source material streams:
Source separated – Incoming recyclables have been presorted at the point of collection, so only minimal processing is required. The main purpose is to remove residual contaminants and prepare materials for market.
Dual stream – Recovered materials are received in two streams, typically fiber (newspaper, magazines, mixed paper, cardboard, etc.) and commingled containers (plastic, glass, and metal). Separation of the materials is accomplished by a combination of automated equipment and manual sorting.
Single stream – Recovered materials are received in a single stream, with fiber and commingled containers combined. The first stage of processing typically utilizes equipment that separates the material into two streams (fiber and containers), which are further sorted using equipment similar to that used in dual stream MRFs.
Mixed waste – MSW is processed using various technologies to separate mixed recyclable materials from the waste stream. Recyclable materials are then processed using equipment similar to a single stream MRF. Some facilities process the entire waste stream, while others target commercial waste or loads rich in recyclables.
Advancements in automated processing equipment have resulted in the conversion of many source separated and dual stream MRFs into single stream MRFs and have led to improvements in the performance of mixed waste MRFs or “dirty MRFs”. As communities strive to achieve waste diversion rates of 50% or higher, they are recognizing the critical role one or more of these types of facilities will play in their overall waste management system.