Recycling

There are four commonly used methods for collecting recyclable materials: curbside collection, drop-off centers, buy-back centers, and deposit/refund programs. The fastest growing method is curbside collection. There are three major ways in which recyclable materials are collected through curbside programs: mixed wastes, mixed (or commingled) recyclables, and source-separated recyclables.

Mixed-wastes collection is essentially a modification of the conventional municipal waste-collection process. It involves the sorting of recyclables at a central facility, using a combination of automated methods (such as magnets to sort iron-containing material) and hand-sorting. An advantage of this method is that it does not disrupt the regular schedule of trash pick-up in the community.

Mixed recyclables are separated from other trash by householders and businesses, so that two streams of material are picked up at curbside: trash and recyclables. This method has a lower contamination level of the recyclable stream than the mixed-wastes collection system. Public education is necessary if this program is to work well, so that people know what is recyclable and what is not.

Source separation involves householders and businesses performing a higher level of sorting before pickup. The advantage of this method is that the recyclable materials are well-sorted and can be sold at a higher price. The disadvantages are that source separation requires a high participation rate, as well as more or more-complex collection vehicles.

Drop-off centers are central places where householders or businesses can take their accumulated recyclables, rather than having them picked up at-site. This method requires public education and a high participation rate if it is to be effective. Like other collection systems, it works best if there are positive incentives to encourage participation (such as monetary redemptions), or negative ones to not participating (such as landfills refusing to accept recyclable materials, or charging a significant fee to take them).

Redemption or buy-back centers are similar to drop-off centers, except they purchase recyclable materials. Buy-back centers pay a unit-fee for such recyclable materials as newspapers, soda cans, glass, and plastic bottles. This system is also effective for the collection of metals, such as aluminum, lead, and copper.

After recyclables are collected and sorted by any of these methods, they are sent to a materials recovery facility (MRF), where they are prepared for re-manufacturing. A MRF can typically process 25-400 tons of material per day. Sorting is done both manually and mechanically. Newspapers are usually the major paper item, but MRFs also sort corrugated boxes, telephone books, magazines, and mixed-paper materials. MRFs also process aluminum, glass containers, plastic bottles containing polyethylene terphthalate (PET), and milk and detergent bottles containing high-density polyethylene (HDPE).