Residue Management: Is Technology the Solution?

Residue rates in Ontario have more than doubled over the past 15 years from 4% to a provincial average of 9.6%. Dual-stream residue rates are in the range of 7.6% while single-stream rates exceed the provincial average at 11.6% and both are continuing in an upward trend adding stress to the economics of recycling.

cif-blog-july7-pictureManagement approaches to this problem fall into two camps: technology-based solutions that improve sorting capabilities vs. policy & enforcement-based solutions that require residents to recycle in compliance, by separating their recyclables and keeping non-targeted materials out of the Blue Box program.

The question for Ontario programs is which approach makes sense and under what conditions. CIF invited Nathiel Egosi, owner and CEO of RRT Design & Construction, to address the question at the June Ontario Recycler Workshop. With more than twenty-five years experience overseeing 400+ projects including: MRFs, Mixed Waste Processing (MWP) operations and Energy from Waste (EFW) sites throughout the United States and Canada, Nat is a leading subject matter expert in this field.

What is Mixed Waste Processing and is it a viable approach to managing highly contaminated recycling streams?
MWP recovers recyclables from solid waste. All waste – recycling and garbage combined – is collected together in one bin and taken to a facility that uses an extensive array of equipment, processes and techniques to separate materials. The core concept of the mixed waste processing facility is that no resident participation, education, or sorting behaviour is required.

While a MWP facility may seem to be a straightforward solution, far more sorting technology and labourers are needed to contend with the problematic and non-homogenous aspects of solid waste, and the quality of recyclables is often inferior. However, this approach does offer the opportunity for organics recovery as well as preparation for energy from waste (EFW).

There are, numerous variations on this concept, which can be more or less encompassing.  For instance, MWP is often considered as a possible solution for recovering additional Blue Box recyclables from the residual waste stream in parallel with existing curbside organics and Blue Box recycling programs. These other options, which are sometimes termed ‘dirty MRFs’, do not necessarily involve diversion of organics or production of an end product for an EFW facility. They draw on the technology and labour aspects of MWP to contend with the additional sorting challenges.

Adding some of the MWP technology features to a traditional MRF design to better manage residues may sound like an easy fix, but Egosi cautions that there are several important factors to be weighed when considering this approach. Robust MRF sorting capabilities may create the perception that residents no longer need to recycle correctly or fully participate in local diversion programs. The greater expense of the enhanced facility may also lead to increased pressure to accept additional tonnage, regardless of its quality, to ensure costs) are fully amortized. A further risk is that residue levels, if left unchecked, will likely creep further upward and eventually strain or exceed the limits of the newly enhance MRF and leave the same or greater residue problem as at the outset. In short, there will be:

  • Higher processing rates due to greater reliance on equipment and labourers to separate out non-targeted, un-marketable materials
  • Higher landfill fees due to contamination in the inbound materials
  • Reduced revenue due to the degradation of the recyclables (particularly with fibres)
  • Greater health & safety risk exposure for workers.

So what’s the verdict?
Using the MWP approach to complement or enhance programming could be effective, but it must be carefully designed and planned.

“The best advice I can really give is to be clear about the reason for adopting any aspect of the mixed waste processing approach”, says Egosi. “Improvements to the sorting capabilities are intended to manage the residue that is hard to limit or prevent from entering the facility. It is also intended to provide an adequate buffer to residue spikes stemming from changes in the material mix. It is not a license to abandon traditional Blue Box sorting requirements all together.”

Words to the wise
If you’re contemplating a system change, be sure to:

  • Develop a business plan for both the MWP upgrades, and for the proper separation policy & enforcement portion of your waste management program. It’s all about striking a balance. The idea is to improve the sorting capability to minimize current residue management costs. It is not about using downstream technology to deal with poor curbside residue controls.
  • Set a hard limit on the residue levels that will be tolerated.
  • Budget for well-designed promotion and education initiatives that include enforcement strategies. Rigorous and continual educational and enforcement efforts over time have been proven to be effective at keeping residue levels at bay, and it can be more cost effective than managing the residue problem at the MRF.

CIF invites readers to send questions about the Mixed Waste Processing (MWP) approach to Jessica Landry for consideration for a future blog.

We also encourage you to review Nathiel’s ORW slides: Managing Residue: Is Technology a Viable Long-Term Solution (starts at slide 195).