New Life for Glass

Features - Municipal Recycling

Glass recyclers are determined to find viable ways to process glass through single-stream systems.

January 16, 2012

Writing off glass recycling would be a mistake. While it is true that single-stream collection has brought considerable challenges, new processing techniques have helped to address them. Many glass recyclers have not given up on the heavy, easily breakable material—they have just become more creative.

Quality Control
Glass recycling is not the same as it used to be 10 years ago, before single-stream programs and collection trucks that compact material began to proliferate.

Calvin Tigchelaar, president of Resource Management Cos. (RMC), Chicago Ridge, Ill., says, "The combination of compaction collection and the widespread implementation of single-stream programs has caused the quality of glass available for processing to deteriorate significantly over the past 10 years.

"Complex, technologically intense systems are now required to produce glass cullet of an acceptable quality for reuse versus the fairly simple, manual sorting systems utilized 10 to 20 years ago when whole bottle sorting systems were prevalent," Tigchelaar adds.

Steve Sargent, director of recycling for Rumpke Consolidated Cos. Inc., headquartered in Cincinnati, Ohio, also has watched the market go through changes in the past decade.

"As with the fiber markets," Sargent says, "we have seen a great deal of consolidation or departure from the glass business; but, in the past two years we have seen a renewed interest by some of the primary consumers in the glass industry."

Sargent continues, "There has been a challenge for the glass industry to increase its proportion of recycled content in the past due to the availability of collected glass, but we are starting to see that change, especially in our Midwestern service area. In our Midwestern service area, glass is generally left in the single-stream collection programs, and we have designed processing systems to effectively recover it."

RMC and Rumpke also have invested in systems to futher clean up the glass recovered through their MRFs and at neighboring facilities.

Curt Bucey, chief operating officer of Strategic Materials, Houston, says he believes there is a misconception about the level of demand for recycled glass. "We definitely need cleaner material, but I'm happy to take what comes in."

Increasing the proportion of recycled content in the glass industry has been challenging in light of the limited availability of cullet, though Sargent says he has seen improvements recently, particularly in the areas the company serves.

Tigchelaar says, "Consuming markets continue to incorporate increasing percentages of recycled glass cullet into batch mixtures as suitable cullet becomes available." Consumers are seeking more cullet as energy costs and public demand for recycled content have increased.

Necessary Adaptations
Material recovery facility (MRF) operators have had to adapt their systems in several ways to address the issues associated with the commingled collection of recyclables including glass. Operators must consider investments in equipment that will separate mixed broken glass for reuse and prevent glass from contaminating other recyclables.

Many consumers of recyclables claim that single-stream recycling has increased the amount of glass contamination in other recyclables, particularly paper. This, consequently, has reduced the recovery of glass. According to Tigchelaar, in addition to the glass fraction that contaminates newspaper and other items, much of the broken glass that originates in single-stream collection is often thrown out as process residue because it is considered too contaminated to economically recover as suitable feedstock for cullet consumers.

For MRF operators, Tigchelaar says, "Given that broken glass is an extremely abrasive substance, the isolation of this material at a point as early in the process as possible is also necessary to reduce maintenance issues."

Sargent adds, "Primarily, it has required additional capital investment in our MRF processing equipment to effectively remove mixed-color glass for recycling. For example, in our Columbus, Ohio, MRF, Rumpke invested an additional $500,000 in the glass recovery, cleanup and storage equipment to produce recycled glass that is ready for the next stage of processing."

When asked if additional processing at glass beneficiation facilities is a given these days, Sargent does not hesitate to say, "The answer is, Yes. Single-stream glass contains items that are inherently a challenge for both the glass container industry and the fiberglass industry. Additional processing equipment is necessary to remove items such as plastic caps, paper and other organic material. This equipment can include additional screens, optical sorters, metal detection and increased manual QC (quality control) stations."

On the Slow Upswing
Bucey says the amount of glass lost to residue in single-stream programs varies by facility and is a matter of how much attention is devoted to finding and recovering mixed broken glass as well as of how worthwhile it is to invest in recovery.

Also, consuming facilities have had to change the way they handle material that originated from commingled programs. "The consumers of recovered glass have had to enforce their inbound quality standards so this raw material will not have a negative impact on their finished product, whether it is a new distilled spirits bottle or a roll of fiberglass insulation," according to Sargent.

"Other facilities have no market in their areas for mixed broken glass or have a market that is too far away to be economically feasible," Tigchelaar says.

Sargent, who also supports the notion that the amount of glass lost depends on the effectiveness of the single-stream processing system, shares an example of how one of his Rumpke facilities operates: "Rumpke's new MRF in Columbus aggressively breaks all glass at the initial stage of the sorting process, then screens this broken mixed-color glass at three different phases in the MRF. By the time the cans, plastics and paper reach the final QC stations, the broken glass has effectively been removed. This does not happen by chance, it has been designed into the Machinex processing system in Columbus."

In terms of cullet pricing, the recent trend points upward, but that is a very recent development. "The predominant trend in our market has been flat, but we are beginning to see that trend turn a bit more positive," Sargent says.

He thinks the upswing may be due to the commitment by big consumers to use a larger percentage of recycled glass. "In some cases, [the] minimum recycled content standard for their end products is driving this renewed interest. In the construction industry, we see the Leadership in Energy and Environmental Design (LEED) certification process for recycled content in fiberglass insulation as another positive influence on this market."

Sargent continues, "Rumpke feels the demand for good, clean glass will grow over the next five-year time period."

Tigchelaar says he has a positive outlook for glass recycling in the next five years. "Consumers will continue to utilize increasing volumes of high-quality cullet as it becomes available. The outlook for the glass bottle industry is positive, as the industry continues to recapture some market share that was lost to the plastic packaging industry. Markets for good, clean cullet should continue to be vibrant for the foreseeable future," he says.

Wise Investments
Companies with glass beneficiation facilities know broken glass coming from single-stream programs requires a proper cleanup, which often necessitates a variety of technologically advanced equipment, including optical sorters. However, the incoming material needs to be of reasonable quality to begin with.

Tigchelaar, whose company is able to process most of the material coming through its facilities through its glass cleanup system, says, "Mixed broken glass originating from single-stream MRFs (ours included) is a very challenging material to convert into anything of value." He continues, "While elaborate and technically amazing systems are available to remove contaminants and sort glass particles by color, this equipment cannot be expected to function acceptably unless the feedstock presented has been cleaned up appropriately."

Rumpke also prefers to see the cleanup process through, according to Sargent.

"Rumpke believes in a comprehensive plan to increase recycling in the future, which includes the recycling of glass bottles and jars. Our residential and commercial customers want to recycle their glass containers, so it is our challenge to do this in the most cost-effective manner possible. Coupled with the regional demand for our processed glass, Rumpke feels the additional investment is both warranted and good business," he says.


The author is assistant editor of Recycling Today and can be reached at