10 Points that Explain Mixed Waste Processing

Mixed waste processing (MWP) is getting increasing attention as another means of recycling and increasing diversion rates. Here’s a look at some of some of the advantages and challenges.

1. What exactly is mixed waste processing?

Mixed waste processing involves no generator separation of waste, with all waste processed at what’s been called a “dirty” material recovery facility (MRF). Recyclables are then pulled out at the MRF. It’s the other way to collect household recycling, an “all-in-one” method, according to GreenBlue, an environmental nonprofit organization based in Charlottesville, Va. The group said MWP facilities comprise less than 5 percent of all MRFs in the United States.

2. It’s becoming more popular as a means to increase recycling.

MWP can significantly increase recycling rates of certain materials and the diversion rates of municipal solid waste (MSW) in general, according to a report compiled by Fairfax, Va.-based waste consulting firm Gershman, Brickner & Bratton Inc. (GBB) and commissioned by the Plastics Division of the American Chemistry Council (ACC).

3. Technology is helping make that recycling increase possible.

The GBB report states that potential growth could come primarily because of improvements in processing technologies, such as optical sensors that can identify and separate specific plastics. MWP facilities use a range of new and existing technologies to separate recyclable commodities from MSW. Those technological advances that make the operations “different and in many respects better” than previous versions, which can help communities recycle at higher rates than with existing collection systems.

4. Mixed waste processing is evolving from something else historically.

Operators used to design MWP facilities primarily to capture waste for energy recovery. But now, their potential as part of the mix to increase recycling rates has changed the focus. For one reason, even after consumers have separated out their recyclables, an MSW stream may contain half or more of the total volume of recyclables, the GBB report states.

5. Long-term realities such as facility siting difficulties and our throw-away society are other arguments for MWP.

Steven Viny, CEO of Cleveland-based waste processor Envision Holdings, gave four basic assumptions in a presentation on mixed waste processing. They all argue for a place for MWP.  We are a coal-burning society and will remain one; we are a throw-away society and will remain one; siting and permitting of new waste-to-energy facilities and new electric power plants isn’t going to become easier; and financial institutions are adverse to risk.

6. Combining MWP facilities with existing large materials recovery facilities (MRFs) can increase diversion rates.

Combining MRFs and MWP systems have the potential to significantly increase both the volume and total revenue from recycling materials, according to the GBB report. The potential exists to divert 180 percent more high-value metals and plastics from landfill than are diverted currently.

7. There are challenges, such as resolving the contamination issue.

The GBB report identifies some obstacles that MPW need to address. For example, in some cases technologies may deliver more volume of recycled material, but increased contamination could result in reduced commodity prices. There also is a need for better data and case studies to demonstrate realistic recovery numbers for MWP.

8. Low need for consumer involvement is a double-edged sword.

MWP requires no consumer participation, education or sorting behavior, GreenBlue points out. While it minimizes demands on the generator end, that also eliminates opportunities to educate consumers on the impact of their consumption habits. And lack of separation at the consumer end can lead to more health risks for workers exposed to hazardous waste and other waste concerns.

9. There are limitations on MWP effectiveness in the big picture.

GreenBlue concludes MWP’s best role is as co-location with a landfill or waste-to-energy facility to provide a final sort of MSW prior to disposal. Concurrent organics source separation would greatly decrease contamination.

10. But it’s another tool in the box in efforts to increase diversion.

GBB provides a more promising view in its conclusions. “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 non-recycled materials is an excellent approach to managing post-use materials more sustainably.” Adds 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.”