Biodegradable Plastics

Are they the best choice for my company?

Many companies are reviewing their purchasing policies in an effort to make better decisions that could reduce their company’s overall environmental impact. One category that often makes it to the top of the list is the purchase of plastics. Plastics can represent a large percentage of a company’s purchases and today, there are many options available to “green” these purchases.  Plastics can be in the form of garbage bags, plastic bags, food containers, water bottles, or other packaging material.  For the purchaser trying to understand all the new green plastic terms and how they can affect their company’s environmental footprint can be confusing. Trying to write purchasing policies to ensure better choices are made can be outright overwhelming.

First a few definitions:

Degradable Plastics – these plastics undergo significant change in its chemical structure under specific environmental conditions resulting in a loss of properties.  Plastic can be degradable but not necessarily biodegradable.

Biodegradable Plastics– these are plastics that can decompose into carbon dioxide, methane, water, inorganic compounds or biomass.  To be considered biodegradable this decomposition has to be measured by standardized tests within a specific time period will vary according to the disposal method chosen.

Oxo-Degradable Plastics are made by blending an additive to provide oxidative and then a biological mechanism to degrade them. Degradation is achieved by a two step process. The plastic, when exposed to oxygen (and other factors such as light, heat, stress can accelerate this process) transforms to low molecular weight fragments.  The second part of the process is that these fragments are then consumed by micro-organisms.

Compostable Plastics are capable of undergoing biological decomposition in a compost site as part of an available program such that the plastic is not visually distinguishable and breaks down to carbon dioxide, water, inorganic compounds and biomass, at a rate consistent with known compostable material. These new generation plastics are usually derived from renewable raw materials such as starch (corn, potato), cellulose, soy protein, etc.  Standards exist to verify compostability of these products.  Three criteria must be met to be considered compostable.  The plastic must:

Biodegrade – break down into carbon dioxide, water, biomass at the same rate as cellulose

Disintegrate – the material must be indistinguishable in the compost

Eco-toxicity – the biodegradation must not produce any toxic material and the compost can support plant growth.

How to choose which plastic to buy for your company?

The first question that can help you make the correct decision is what will happen to your waste once it is collected?

  • If your facility does not have a separate collection for compostable waste, compostable plastics may not be the best choice.  For compostable plastic to break down, it needs to be placed in a composting site. Today, there are some commercial composting sites available, but not many and their availability varies from area to area.   If your clients bring home the plastic container (for example carry-out food), and composting exists in their area, compostable plastic containers could be a wise choice. It is important to verify that the plastic compostable products meet the Standards dictated by the local composting site.
  • If your waste is sent to a landfill site or a solid waste treatment centre, it may never be exposed to oxygen and therefore the degradation process may never take place. Landfill operators do not have consensus on the benefits or the validity of biodegradable and oxo-degradable plastics once these plastics have reached their site.

Reducing overall plastic use should be your first choice.  Buying more concentrated cleaning products, using reusable dishes instead of disposable ones, providing jugs of water instead of individual water bottles are ways to reduce your overall plastic consumption. Another option is to choose the correct plastic product to fit the need.  The can liners in most offices do not need to be extra duty. Simply by switching to a regular strength or a high density plastic for your desk-side office garbage bags, the plastic going to the waste stream can be reduced by up to 50%. Increasing your recycling options to prevent most types of plastics from going into your solid waste stream is another way to reduce plastics from going to landfill sites. Many local governments and local recycling companies have programs available to help commercial facilities collect and recycle additional products.

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L'expert / The Expert