Recovering Plastic Film from a Mixed-Waste MRF
At Issue
A study was done at a MRF operated by Willamette Resources, Inc. (WRI) just outside of Portland, OR, during two weeks in April and two weeks in late July and early August 1998. Its purpose was to answer four key questions related to the feasibility of plastic film recovery at a mixed-waste facility:
- What system changes are required to accommodate the recovery of plastic film?
- How much film is in the mixed-waste stream? Is there enough to justify recovery efforts?
- Can the plastic film recovered meet the quality specifications of the markets that are demanding the material?
- Is it economically viable to recover plastic film at a mixed-waste MRF?
Findings
In the order of the above questions, the study found the following:
1. The MRF was designed originally to recover approximately 10 materials from the dry commercial-waste stream. Plastic film was added by making the following few adjustments to the sort line:
- One sorter (at a cost of approximately U.S.$81 for an eight-hour shift) was added to the pick line for recovery of the plastic film.
- A secondary exhaust fan was placed on the MRF line to remove grit contamination from the collected film.
- A bunker, previously used to store mixed paper, was dedicated to storing plastic film.
In addition, MRF management and staff received training in what plastic films to recover and in acceptable levels of contamination. MRF supervisors took time to ensure that the tests were conducted according to protocol and set quality specifications.
2. An average of approximately 3500 lbs of plastic film was recovered per day during the two sorting periods. The WRI MRF processes approximately 125 tpd. Assuming these recovery levels are typical, approximately 450 tons could be recovered annually. Approximately 400 lbs/hr were processed at WRI during the test sorting periods.
3. WRI initially experienced significant problems with contaminants. They included grit, PVC, and polyurethane foams. However, after additional training, a visit by the MRF manager to the Boise Cascade facility (the market for the material), and slight equipment adjustments, the recovered film met the Boise Cascade specifications.
The film processed at WRI contained some moisture and a level of contamination that would not meet the material specifications of other higher-value film markets. However, overcoming that deficit was beyond the scope of this study.
4. This case study indicated that recovery of plastic film is economically viable, given the price paid by the Boise Cascade market and WRI's cost structure and operating practices. Labor and baling expense comprise the major operating costs associated with film recovery.
Economics
The total operating cost per pound of film recovered at WRI during the sorting period was approximately 4.6 cents. The average net cost was approximately $0.014/lb. Cost savings were achieved through reduced transportation and disposal costs (tipping fee) of the MRF's residual waste.
The clearest indication that recovering plastic film from a mixed-waste MRF can be successful is WRI's adopting plastic film as a standard recoverable material in its ongoing operations.
Although WRI finds it economically viable to process plastic film, other mixed-waste MRFs must assess their own waste stream, size, labor costs, regional markets and disposal costs before deciding whether it can be viable for them
The previous article was adapted from the March 1999 report, "Recovering Plastic Film from a Mixed-Waste MRF," prepared for the American Plastics Council by Cascadio Consulting Group with assistance from ReSourcing Associates.