On this page:
- Recyclable and Recycled
- Is a tree falling in a forest biodegradable?
- What do the recycle numbers on the bottom of a plastic container really mean?
- What makes a plastic item biodegradable if one of these biodegradable additives is used?
- Why is this biodegradable treatment necessary?
- What are some of the advantages of the additive?
- Does the additive affect the parent materials?
- Are there plastics made from plants that are better to use?
- What is Biodegradation?
- How long will it take a plastic item to degrade?
- Why do ASTM Testing to verify biodegradability?
- What is the ASTM D5511 test?
- Will the plastic item start to degrade before it is used?
- What is the difference to composting?
- What about the term degradable, is that the same thing?
- What are the products of biodegradation?
- Why use a biodegradable material instead of an oxodegradable material?
- If biodegradation produces methane, is that a problem for global warming?
- Others say it is better to recycle used plastic items, is that true?
- Will a landfill biodegradable plastic affect the ability to be recycled?
- Is there any toxic residue left after biodegradation?
- Is the additive safe?
1. Recyclable and Recycled
Simple as it may seem, many people do not understand the difference. Recyclable means that an item can be recycled. But it will only be recycled if it is taken to a recycle centre and sorted out from other material. Most of our consumer items of convenience are disposable one-off-use items and are used while out of the house and hence they get dumped to a trash bin to go to a landfill. This is where 93% (USA ) of our plastic trash goes. Hence while an item is recyclable, there is only a small chance of it getting recycled.
Recycled on the other hand means the item is actually recycled for another use.
Some manufacturers will proudly tell you their product is now environmental as it is recyclable. Well knowing that only approx 1 out of ten items get recycled (the others go to a landfill or become litter), how environmental is it?
2. Is a tree falling in a forest biodegradable?
Most of us would not even think twice about saying ‘Yes of course it is’. All trees eventually rot and decay away; it is part of nature’s way. Not so if we listen to some regulatory agencies that say unless an item can biodegrade in less than 12 months, it is not allowed to be called biodegradable. A fallen tree can take 20 or more years to decay away so why do we not apply the same rational to biodegradable plastics? Twenty years is a lot better result in order to eliminate our plastic waste than the current expected time of 300+ years for a plastic item. These agencies need to acknowledge that putting a landfill biodegradable additive into a plastic to make it biodegrade over a number of years is still biodegradation and it is a better option than not allowing the use of these additives. Otherwise we are thereby trapped with plastic waste for eons.
3. What do the recycle numbers on the bottom of a plastic container really mean?
Resin identification coding systems are the marks we see in plastic containers (surrounded by arrows). We all have seen it, the Recycling logo that screams, Throw me in the Recycling bin and I will be recycled! Well if you look more closely you would
notice that in the middle of the chasing arrows there is a number. Do you
know what those numbers represent? It is very important to know and as explained by Enso Plastics;
- PET (Polyethylene terephthalate) – #1s are usually Fizzy drink
bottles, oven-ready meal trays and water bottles . These items are
recycled at a rate of 19.5%, the highest of all recycled items.
- HDPE (High-density polyethylene) – #2s are Milk bottles, detergent
bottles, yogurt and margarine tubs, cereal box liners and grocery, trash
and retail bags. These items are recycle at a rate of 10.7%, the second
highest of all recycled items.
- PVC (Polyvinyl chloride) – #3s are Cling film (plastic food wrap),
vegetable oil bottles, loose-leaf binders and construction products such as
plastic pipes. These items are recycled at a rate of 0% which means, not
at all….so what’s the point of throwing them in the recycling bin?
- LDPE (Low-density polyethylene) – #4s are typically dry cleaning
bags, produce bags, trash can liners, bread bags, frozen food bags and
squeezable bottles, such as mustard and honey. These items are recycled
at a rate of 5.6%.
- PP (Polypropylene) – #5s are Ketchup bottles, medicine bottles,
aerosol caps and drinking straws. These constantly used items are
recycled at a rate of 1.7%.
- PS (Polystyrene) – #6s are Compact disc jackets, grocery store meat
trays, egg cartons, aspirin bottles, foam packaging peanuts and plastic
tableware. These items are recycled at a rate of 0.8%.
- Other – #7s are Three- and five-gallon reusable water bottles, certain
kinds of food containers and Tupperware. These items are recycled at a
rate of 6.1%.
As you can see, recycling rates even for the most commonly recycled
items are pretty low. Even though Recycling is important, waste continues to accumulate in landfills, at sea, and shipped to other countries.
4. What makes a plastic item biodegradable if one of these biodegradable additives is used?
The additive added to the material entices microbes to attack the material once discarded into a landfill. The additive has passed the FDA review to be suitable for packaging of food products. It is completely organic, non-starch based and non destructive to the environment.
5. Why is this biodegradable treatment necessary?
Plastics do not exist in nature, and this is what makes them so useful. They are inert and inexpensive to use. But it also creates a problem. Regular plastic is not easily biodegradable and will last in the environment for centuries, maybe forever.
6. What are some of the advantages of the additive?
When mixed into raw plastic at a small ratio, it allows plastic to break down—but only when placed in a microbe rich environment, such as a landfill or compost facility. It provides the best of both worlds. The biodegradable plastic product is still as useful as it ever was. Consumers like it because they still get all the safety and convenience that plastic brings, while at the same time knowing they are not leaving a nightmare for our children’s children.
7. Does the additive affect the parent materials?
The base resin retains all of its original properties and shelf life.
Recyclability of the product is completely unaffected; recycling number remains the same.
The final product is essentially indistinguishable from the non biodegradable current product. But when it’s finally discarded to a landfill it will return to the cycle of life.
8. Are there plastics made from plants that are better to use?
Polylactic Acid or PLA is the most common plastic referred to when bioplastics are mentioned. It is a plastic made from corn. It therefore utilizes a food source to create the plastic which may result in higher food prices, require the use of Genetically Modified Organism seed and requires heavy pesticides in the farming process. It does not biodegrade unless placed into an industrial composting facility, and overall requires the use of more fossil fuels in its planting, harvesting and processing than traditional plastics. For PLA to degrade it needs a composting facility with high heat and moisture. Without those conditions, PLA will not biodegrade and will sit in a landfill like other plastics.
Other manufacturers are claiming their bottle plastic material is derived from sugar cane. The final plastic product produced is still the same plastic molecule made from petroleum based. This ideology is addressing only the front end or manufacturing end of the plastic and does not address the back end or final disposal of the material. As a consequence it has the same lack of decomposition properties and will not degrade in a faster timeframe than a petroleum based plastic.
9. What is Biodegradation?
Biodegradation is the secretion of acids by microbes which break down the molecular structure and emit methane gas or CO2 and leave behind highly nutritious soil. The entire mass must be broken down into these things to be considered biodegradable.
10. How long will it take a plastic item to degrade?
The biodegradation time of a product depends on a variety of factors. The thicker the plastic section the longer it will take to degrade. Membrane films are expected to degrade in 45 days or so. Thicker sections may take 1- 5 years. If the plastic is put into a dry landfill it will degrade slower than a more actively managed water moistened landfill. The main point to realise is this: whether it takes a few months or multiple years it does not really matter. What does matter is that after some limited time, the product will no longer be around.
11. Why do ASTM Testing to verify biodegradability?
With so many manufacturers and retailers offering ‘Green’ products it has become confusing to distinguish between what is a genuine biodegradable product, what is a compostable product, what is a degradable product and what are unsubstantiated claims. ASTM tests are tests recognised internationally as being the bench mark of verifications. The ASTM test D5511 is a test performed by an independent laboratory to verify claims of biodegradability in anaerobic conditions.
12. What is the ASTM D5511 test?
Biodegradation occurs through naturally-occurring micro-organisms and happens in both aerobic (compost) and anaerobic (landfill) environments. Once in a landfill and covered by a few metres, the conditions become anaerobic. Hence the need for the ASTM D5511 test. This is a Test Method for Determining Anaerobic Biodegradation of Plastic Materials under High-Solids Anaerobic-Digestion Conditions.
13. Will the plastic item start to degrade before it is used?
No. It will only start to biodegrade once it is put into a microbial rich environment such as a landfill. Before that the item retains all of its original properties.
14. What is the difference to composting?
There is significant confusion about composting and biodegradation. Composting is only one form of biodegradation. There are commercial composting facilities around but they are few and far between. In composting, oxygen is nearly continuously made available in the pile through mechanical means. Hence aerobic degradation is the only main degradation that occurs in a composting facility. The landfill biodegradable additive will attract both aerobic and anaerobic bacteria and cause the plastic to break down in either situation. Therefore the plastic waste will degrade either in a composting facility or in a landfill environment.
At this time, commercial composting is not wide scale in the United States and compostable plastic products that are disposed of almost always end up in a landfill, where they will not biodegrade any time soon.
15. What about the term degradable, is that the same thing?
No. Degradable means the plastic will break down into smaller and smaller parts. It does not refer to any biological activity. The products of degradation may simply be small parts of the original material and no conversion to biodegradation products has occurred.
16. What are the by-products of biodegradation?
In a composting or oxygen rich environment, the by-products are CO2, water and humus (biomass) which can make a good fertilizer.
In an anaerobic environment, (such as deep in a landfill) the by-products of biodegradation are methane (CH4) and humus (biomass).
17. Why use a biodegradable material instead of an oxodegradable material?
An oxodegradable material uses metal ions as an additive in the plastic. As the ions attract oxygen they break down the plastic molecules into smaller and smaller lengths. This has nothing to do with biological activity. For an oxodegradable material to degrade it has to be in the presence of oxygen and sunlight. Without these the material will undergo little to no degradation and last just as long as an untreated plastic would. As long as the product is in the presence of oxygen, the material will start to break down, hence an oxodegradable product will start to break down while sitting on a warehouse shelf. This does NOT happen with a biodegradable product.
18. If biodegradation produces methane, is that a problem for global warming?
This has a two part answer.
a) Methane in the Earth’s atmosphere is an important greenhouse gas with a global warming potential of 25 over a 100-year period. This means that a methane emission will have 25 times the impact on temperature of a carbon dioxide emission of the same mass over the following 100 years. Methane has a larger effect but for a briefer period (a net lifetime of 8.4 years in the atmosphere), whereas carbon dioxide has a smaller effect for a longer period (over 100 years). Usually, excess methane from landfills and other natural producers of methane are burned so CO2 is released into the atmosphere instead of methane. Since methane does have a higher global warming potential than CO2 then one of the faster ways to mitigate global warming is to prevent methane reaching the upper atmosphere. (http://en.wikipedia.org/wiki/Methane) Hence part (b) of the answer.
b) As of October 2010, there are approximately 526 operational LFG energy projects in the United States and 515 landfills that are good candidates for projects that could turn their gas into energy, producing enough electricity to power more than 665,000 homes. Producing energy from LFG avoids the need to use non–renewable resources such as coal, oil, or natural gas to produce the same amount of energy. This can avoid gas end–user and power plant emissions of CO2 and criteria pollutants such as sulphur dioxide (which is a major contributor to acid rain), particulate matter (a respiratory health concern), nitrogen oxides (NOX), and trace hazardous air pollutants. http://www.epa.gov/lmop/basic-info/
19. Others say it is better to recycle used plastic items. Is that true?
In theory yes. The EPA promotes reduce, recycle and composting (a form of biodegradation) as ways to reduce waste. http://www.epa.gov/osw/conserve/rrr/index.htm. In reality only 7% of plastics are recycled in the USA, the rest end up in a landfill. Therefore while some plastic items can be recycled, only a few of them ever make that journey. Most would still end up buried in a landfill. The math is simple to perform: One hundred percent of plastic items discarded into a landfill biodegrading or only seven percent of plastic being recycled while the rest persist for hundreds of years.
A report was recently published (from http://ensobottles.com/blog/2010/08/why-recycling-is-not-enough-to-solve-plastic-bottle-pollution/ )stating that recycling only begins to have a positive environmental impact once rates of 50% or higher are achieved. This is why it is a better environmental solution to have both biodegradable and recyclable. It is going to take decades to get recycle rates up to the 80 – 90% range. Unless changes are made to switch to biodegradable products we will be continuing to contribute to the overwhelming global plastic pollution problem.
Landfill biodegradable plastics are a solution we have available to us today. The plastics fully integrate into the existing recycling infrastructure and for all treated plastics that end up in landfills they will naturally biodegrade to biogas and soil. Plus, the methane can be used, and is being used at hundreds of landfills to create clean energy thus offsetting the need to use additional fossil fuel for electricity.
20. Will a landfill biodegradable plastic affect the ability to be recycled?
No. The treated plastic can be recycled like any product. The biodegradation aspect does not change any of its recyclability properties. It is worth noting that plastics only get recycled a number of times and eventually all get discarded. Therefore biodegradation is the ultimate sustainable solution to our plastics problem.