There have been efforts to make plastic biodegradable since the 1970s. The first wave consisted of putting some starch filler in plastic. The result was that the starch biodegraded somewhat, but the plastic was unaffected. Today polylactic acid has been developed as new, but it doesn’t degrade unless it is subjected to prolonged higher heat than occurs in nature.
PLA, or corn-based biodegradable plastic, was said to be the first generation of biodegradable plastic, even though its primary manufacturer, Naturworks, states that it will not biodegrade in any natural environment, nor in landfills. PLA, Poly Lactic Acid, biodegrades only in commercial compost facilities - and many commercial compost facilities refuse to accept PLA. It is made and promoted by corporate giants that have huge financial and political power, such as Cargill, Inc., but it has many drawbacks.
It is billed as ***'sustainable,' as it is based on food sources, primarily corn. However, if all of the disposable plastic products in the world were made out of corn, 238,500,000 tons of corn would be used to make plastic. Prices for corn would rise dramatically, and third world hunger would increase even more dramatically. There are currently 1,000,000,000 hungry people in the third world, says the UN. If the amount of plastic disposables, such as packaging and drinking cups from fast food stands used in the US each year were all made of corn, it would take 18% of the country's farm land to fill the need. That is enough food to feed over 600 million people, people who need that food desperately. If we imagine their condition worsening only slightly, the result could only be a humanitarian catastrophe of appalling proportions. That is the real ramification of 'sustainability' in today's world.
Furthermore, PLA isn't a very good plastic. It imparts an off taste to water when used for water bottles, it melts when used as soup spoons, it's weak, and therefore items made of it are heavy, and it has a short shelf life, sometimes becoming a sticky mess while still in the warehouse. What's more, no recyclers accept it for recycling except the company that manufactures it, which ships it across the US to its one recycling center. In fact, recyclers that don't manufacture PLA, dislike PLA and are trying to ban it, because it gets confused with more conventional plastics, and ruins their recycled plastic batches.
Even the few commercial composters which accept PLA products have a limited appetite for PLA, because it adversely affects the compost batch as too much PLA makes the compost too acidic. One bottle manufacturer did a survey of commercial composters and found that 90% of those surveyed would not accept PLA bottles. Furthermore, PLA cannot be composted by home composters - PLA requires elevated heat beyond what home compost processes generates to compost. The most peculiar thing about calling PLA compostable, is that it leaves no residue in compost, and so it gives no contribution to humus. The ASTM standard for compostable plastic, ASTM D6400, actually requires that compostable plastic makes no contribution to humus.
The second effort was to put chemicals in plastic, oxodegradable chemicals that responded to heat or ultra-violet light by causing the plastic to oxidize somewhat, in the presence of oxygen. This sometimes resulted in fragmented plastic, but no proof of ultimate biodegradation was ever established.
The next effort was to reduce molecular weight of the materials after typical disposal condition by using oxo technology then it produce CO2 and biogas. But, it is still longer period of time to biodegrade, and there is still physical property issues as well.
The 2.5th generation plastic oxo - biodegradable plastic was very different than the the previous generation of biodegradable plastic called PLA, starch-based plastic, or 'spudware or normal oxo-degradable plastic. Oxo-biodegradable plastic had many advantages over PLA-It was invulnerable to water, one might adjust it to the desired biodegradation rate, some products could contain recycled content, it could be recycled, it didn't diminish the grain supply, it was stronger, less expensive, and was made from an otherwise useless industrial byproduct, light naphtha. (Light naphtha is a highly volatile faction of crude oil that cannot be made into gasoline, diesel, fuel oil, or jet fuel.**)
This 2.5th generation biodegradable plastic is little known in the US, but is is well established and widely used in Europe. Tesco and Carrefours, the largest grocery chains in the world, and in France, respectively, package their customers' groceries in oxo-biodegradable 't-shirt' bags. In fact, the largest bakers in Mexico and South Africa package bread in oxo - biodegradable bags, and oxo - biodegradable plastic is becoming common in India and China. The US is so far behind the curve on this, that it is a little embarrassing. (Update: Tesco has stopped using biodegradable plastic shopping bags, citing a study by DEFRA which reflected all of the issues I have cited.) Read the DEFRA report by clicking here.
Oxo - biodegradable plastic doesn't biodegrade when deeply buried in landfills*, because it requires an initial phase of degeneration which required certain environmental factors-oxygen and one of the following three circumstances-heat, UV light, or mechanical stress-and because the subsequent biodegredation part of the degredation only works in oxygenated environments. These circumstances don't exist when deeply buried in landfills, so oxo-biodegradable plastics don't have any benefit for products deeply buried in landfills. Oxo - biodegradable products may, however, offer a benefit if litter is the primary concern, as they degrade in the presence of UV light.
There is a potential problem with UV initiated degradation, however - if it becomes common and products made with oxo-biodegradable additives enter the recycling stream in large numbers, the resulting plastic could have a short lifespan if placed in sunlight. This would be a big problem for items made with recycled plastic such as plastic tarps.
Highly effective for most troublesome plastic products
There is now a third generation biodegradable plastic product which is the standard plastic we use daily, light naphtha based plastic, with a masterbatch additive (ENATM or Earth Nurture Additive,) that will cause it to biodegrade without the need of heat, UV light, mechanical stress, or oxygen. This third-generation plastic is called micro - biodegradable plastic, and it biodegrades when placed into the ground due to the action of micro-organisms naturally occurring in soil.
We now have ENATM 2.0 masterbatch additive formulas for biodegrading all common plastics - Polypropylene, Polyethylene, HDPE, LDPE, LLDPE, Polystyrene, Expanded Polystyrene, Nylon, and many others, including PLA. Products made with our ENATM 2.0 additives are recyclable, invulnerable to water, don't diminish the grain supply, and are much less expensive than bioplastics. Products made with our additives also have the advantage of having the same shelf life as regular plastics, unlike PLA and oxo - biodegradable plastic, as it does not biodegrade until it is in the presence of soil micro-organisms.
Additionally, this new ENATM micro - biodegradable plastic will definitely biodegrade when buried in the ground in either aerobic or anaerobic environments, that is, landfills and anaerobic digesters. If ENATM treated plastic is biodegraded in airless or very low oxygen environments, such as landfills or anaerobic digesters, it produces valuable methane gas. Over 60% of landfilled solid waste in the United States is disposed of in landfills that are tapped for methane, and the resulting methane, which is essentially the same as natural gas, can be used for many purposes. It is being piped into homes for cooking and heating, it is piped to factories for industrial production, it is used to run turbines to make electricity, and it is used to operate vehicles such as buses, taxis, and private automobiles. Few Americans know that millions of vehicles are being run on natural gas / methane. The latest in natural gas storage, adsorbed natural gas tanks, makes the use of methane in vehicles safe, inexpensive, and convenient.
|BIODEGRADABLE PLASTIC TECHNOLOGIES|
|ENA™||Polylactic acid Compostable Bioplastic||Oxodegradable Additives||Starch mixed with Plastics|
|Additive added to conventional plastics||YES||No, the material itself is compostable||YES||YES|
|Method of degrading||Stimulates wild microbes to eat plastic in landfills, soil, or natural bodies of water||Intrinsically degradable, but only in commercial compost facilities, will not degrade in landfills||Chemically breaks down plastic when baked in oven or intense UV, followed by biodegradation - if baking is sufficient||The plastic does not degrade; only the starch degrades, leaving the plastic intact|
|Common names of brands||ENA™||PLA, corn plastic, Natureworks Igneo||Symphony, EPI, Wells Reverte, D2W, Noebeide||Generic|
|Liklihood of biodegrading in landfiils||100%||Will not biodegrade in landfills||Unlikely, due to absence of pretreatment||Starch portion only degrades in landfills - plastic will not|