The Sustainable Cities Network looked
at a new method used in Austin, Texas to recycle glass. The city faced challenges to recycling glass seen in Montana, and has begun a program to incorporate glass into public works projects similar to keep the glass out of the waste stream. While there is a unmet demand
for glass bottles and jars for recycling, which can be indefinitely recycled,
many communities are finding it more feasible to establish a local use for glass that can be maintained in community projects.
In Montana, opportunities to keep glass out the
landfill are unavailable in most communities. The challenges and solutions in
the article represent opportunities for glass recycling in Montana. While there
is some potential for a premium market to fully recycle glass bottles through
back-haul options and rail lines, establishing a program to collect large
enough volume of glass with high enough quality control to utilize such outlets
remains to be seen in recent times in the Treasure State.
The article mentions the contamination of glass
product from other material though a co-mingled process that combines most of
all recycled items into one collection stream. While some materials, such as
metals, can be easily recovered through such a process, glass may be an item
that will need to be kept separate to have a valuable reuse. In Montana, many
communities still have source separation through the use of drop-off sites,
traditional curbside with multiple bins, or collection events. Even at events,
quality control can be a challenge as the collection of durable ceramic glass
containers (like plates and cups), household, and auto glass often finds its
way into glass bottle and glass jar collection. These items can prevent an
entire batch of glass bottles and jars from being recycled back into glass at
plant, as well as cause problems in the pulverizing or crushing processes to
produce an aggregate product.
Logistically, glass is difficult to collect. It is
heavy, creates a physical hazard when dropped or handled in a trash bag without
proper equipment, and can cause hearing damage to unprotected ears when being
dumped into a bin. Even if a community business wanted, it may be able to
provide a collection space for plastics, metals and fibers, but not glass,
since broken glass could prevent a hazard to the users of the site—especially if it is not monitored at all times (which is the case in
most locations across Montana). Despite these challenges, glass provides a
reuse opportunity being seen throughout Montana. Glass can be reused locally
within a community as an alternative aggregate for public works and community
projects. The article mentions the examples of:
"• City of Spokane, Wash.: Crews combined 1,500 tons of
glass cullet with crushed rock. The resulting material was used to create
bedding for the asphalt, a reconstruction project for Market Street spanning
1.25 miles.
• Washington State Department of Transportation: More than 1,200 tons
of glass cullet has been used as bedding for large stormwater pipes.
• New York State Department of Transportation: Engineers used glass
cullet to create a cost-effective filtration system for removing Total
Suspended Solids from concrete slurry during hydro-demolition in 2005."
In Montana, recycled glass cullet—distinct from crush glass for being processes to have dull edges—has been used in public works projects including the freeway near
Boulder, trails at Helena's Community Works Garden, and in a public art project
in Great Falls. The City of Livingston has a permanent pulverizer that
processes glass from as far away as Bozeman, even Missoula. Helena’s
glass provides silica to Ash Grove Cement in Montana City, with any
extra glass stockpiled and pulverized by Headwaters Cooperative
Recycling’s mobile pulverizer. The 2011 Montana
Legislature passed House Bill 594 to ensure there is a use for recycled
glass by requiring the Montana Department of Transportation to use pulverized
glass when it is available, meets specification, and is less cost than other
aggregate.
Glass presents a challenge to recycling, but the
challenge can be overcome. Glass can be used locally in projects that divert
the material from the landfill. As recycling rates increase for other
commodities, the percentage of glass becomes even more noticeable is the waste
stream—in one study, Austin found glass
made up a quarter of their remaining waste. While aggregate is not the highest
use of glass, it is often appropriate to use heavy materials locally, as is
done with concrete and cement, and an established collection process will pave
the way to higher use projects, such as Bayern Brewery’s reuse of
bottles in Missoula.
In the coming months, Recycle Montana will be adding community recycling
guides, case studies on rural recycling successes, and best management
practices to improve recycling across the state. This will include opportunities for durable (household, auto,
cups & plates) glass in addition to bottle and jar recycling discussed
above.
