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Biodegradable plastic bags make sense for your community,
when integrated with composting
Thursday, 03 September 2009 09:06
Author: Administrator
There are a number of communities looking to follow San Francisco’s lead by replacing traditional plastic
shopping bags with “biodegradable” or “compostable” ones. Such a step is a part of sustainable approach and
should be encouraged, when it is combined with the mandate to dispose of these bags along with foods craps
in composting or biodegradable disposal systems (like anaerobic digestion). It is also important that the bags
are truly and completely biodegradable and meet ASTM D6400 for compostable plastics.
Background In March 2007, San Francisco passed an ordinance that large grocery stores and pharmacies are
no longer allowed to give out traditional plastic shopping. In their place, these stores are mandated to use
either recyclable paper bags or compostable plastic bags. Also, consumers are encouraged to provide their
own reusable bags. Smaller retailers are allowed to continue to use traditional plastic bags. Communities can
learn a number of lessons from San Francisco’s experience.
Lesson #1
San Francisco has a well developed residential and commercial food scrap diversion program to augment their
extensive recycling programs. This means that compostable plastic bags can serve two uses. First as a shopping
bag and second as liner for “kitchen catchers”. These make it easier and cleaner for residents to separate
and collect food scraps for collection and composting. San Francisco’s food scrap composting program is an
important element the City’s plan to divert materials from landfills and to reduce greenhouse gas emissions.
Today, San Francisco’s diversion rate is approaching 70% and it is committed to improve upon this mark. Moreover,
by not sending food scraps to a landfill, San Francisco is doing its part to reduce methane emissions into
the atmosphere.
If your community does not have the collection system in place to collect “compostables” or “biodegradable”,
then take steps to create a food waste program along with your yard wastes. The BPI, along with U.S. Composting
Council can help in this effort.
Lesson #2
San Francisco also benefited from California’s stringent plastic bag labeling law. This law says that if a plastic bag is labeled “compostable”, “biodegradable” or “degradable”, it must meet the appropriate ASTM Specification
(in this case ASTM D6400). Plastics which meet this specification will disintegrate and biodegrade swiftly and
safely in a professionally managed composting facility. Without proper labeling regulations in place, purchasers
can not be assured that they will be buying a product that is compatible with the composting process.
Lesson #3
There is a great concern amongst recyclers that residents will place their “compostable” bags in the recycling bins and thereby contaminate the quality of the recycled materials. This is, of course, true for any contaminant,
and not just biodegradable/compostable plastics. The biodegradable/compostable bags should be labeled
correctly, and customers encouraged disposing of them in composting systems. As part of the decision making
process, your community leaders should be aware of this and promote proper disposal.
Lesson #4
San Francisco has a long standing concern for litter and identified plastic bags as one of the key contributors
to this issue. (This concern is shared by many other communities). However, “biodegradable” or “compostable”
plastic bags are not going to solve litter issues – that is a people education issue, not a technical one.
To implement a ban on plastic bags with a mandate for biodegradable/compostable bag (whether plastic or
paper), communities should address the following questions:
1. Does your community have the collection process in place to collect and process “compostable” or “biodegradable”
bags along with other organic wastes like food scraps and yard trimmings? If not, the first step is to
setup a collection program, as a way of reaching a 50% or higher of waste diversion goal.
2. Ensure that the proper labeling laws in place. These should cite ASTMD6400. Experience has shown that
without proper labeling statutes consumers will be confused or worse, mislead.
3. Proper labeling/identification of the biodegradable/plastic bag can ensure that recycling streams stay clean.
4.Remember that “bio degradables” are not the solution to litter?
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