Mixed waste processing could increase recycling and waste diversion rates

A new report that looks at processing mixed waste to extract recyclables finds potential to significantly increase recycling rates for certain materials and diversion rates for municipal solid waste (MSW) in general, primarily because of improvements in processing technologies, such as optical sensors that can identify and separate specific plastics.

The report, The Evolution of Mixed Waste Processing Facilities, 1970-Today, by Gershman, Brickner & Bratton Inc. (GBB) of Fairfax, Virginia, notes that mixed waste processing (MWP) facilities use a variety of new and existing technologies to separate recyclables from a MSW.

In a review of evolving technologies, the study’s authors recount how MWP facilities initially were designed to capture high-energy elements from the waste stream for combustion-based energy recovery (also referred to as waste-to-energy). However, today MWP is attracting renewed interest as a means to boost recycling rates. This is important because even after many residents have separated their recyclables, the average MSW stream may contain up to half of the total volume of recyclables and, in some cases, more.

Technological advances make today’s mixed waste processing facilities “different and in many respects better” than older versions, the report’s authors say, which could enable communities to recycle at much higher rates than under existing collection systems.

The authors conclude, “Based on its roots in single-stream sortation, today’s MWP technology appears promising. The results in terms of outputs, net revenue and reduced collection costs could be attractive for some communities. The combination of recycling with energy recovery for nonrecycled materials is an excellent approach to managing postuse materials more sustainably.”

The report also identifies outstanding issues that need to be addressed to achieve these improvements. For example, in some cases technologies may deliver more volume of recycled material, but increased contamination could lead to reduced commodity prices. The report's authors point out the need for better data and case studies to demonstrate realistic recovery numbers for MWP.

The authors also suggest that coupling MWP facilities with existing large material recovery facilities (MRFs) could help communities increase diversion rates.

“GBB finds that combined MRF and MWP systems have the potential to significantly increase both the volume and total revenue from recycling materials. The potential exists to divert 180 percent more high value metals and plastics from landfill than are diverted today,” the report states.

The report was commissioned by the Plastics Division of the American Chemistry Council (ACC), Washington, which is examining methods to increase plastics recovery.

“The goal of diverting more materials from the waste stream to higher uses compels us to explore all options,” says Craig Cookson, director of sustainability and recycling for ACC’s Plastics Division. “As the waste stream continues to evolve, we must consider new strategies and innovations that could help us to meet these challenges.”