The Plastics Environmental Council (PEC) is sponsoring research to produce the first standard specification for landfill biodegradation of petroleum- and natural gas-derived plastics treated with additives to speed up anaerobic biodegradation. Such a standard would be a huge help in coping with the estimated 29 million tons of post-consumer nonrecycled plastics that end up in landfills.
Plastics are generally not biodegradable unless they've been specifically engineered to do so, as materials used in food service items are in many areas of California. Petroleum-derived plastics don't usually biodegrade unless they've had certain chemical additives introduced to them during the manufacturing process. The additives don't affect the plastics' performance, and products that contain the additives can be processed with existing recycling methods.
An additive made by ENSO Plastics, a PEC member, includes organic compounds that bond hydrostatically to the material's molecules. When the material is placed in an environment like a landfill, the additive attracts anaerobic microbes that colonize the plastic, digest the additive, and further digest the plastic by depolymerizing it. The final products are either methane or carbon dioxide and humus.
The PEC-sponsored large-scale research and development program will be conducted by the Georgia Institute of Technology and North Carolina State University and aims to produce a specification and a certification seal. The specification will reliably project landfill biodegradation rates for a given PEC-certified product in a given range of landfills over a given range of moisture conditions. The PEC expects the development of the specification to build confidence among regulators, consumers, and businesses in the effectiveness of plastics additives. It estimates the certification seal will be available in 18 months.
The study will be the first of its kind to verify biodegradation rates of plastic waste treated with additives under both laboratory and field conditions, Robert McKnight, the PEC's chairman, said in a press release.
Professor Morton Barlaz of North Carolina State and his team will examine waste degradation rates under both field and laboratory conditions. To produce the specification, they will study petroleum- and natural gas-derived plastics that have been treated with additives from PEC member companies.
The additives are organic substances that encourage anaerobic landfill bacteria and fungi to break down the materials and convert them to biogas methane, carbon dioxide, and biogenic carbon. "Research done so far using standard test methods suggests that the treated plastics could biodegrade completely within five to ten years, depending on landfill conditions," Lisa Detter Hoskin, a principal research scientist at the Georgia Tech Research Institute, who co-chairs the PEC’s technical advisory committee, said in a press release. A network of accredited laboratories will test products made with the biodegradable additives to ensure they degrade within a specified period.
PEC member companies include Biofilms, Bio-Tec Environmental, C-Line Products, ECM, Ecolab, Ecologic, FP International, Pure Plastics, and Wincup.
I think one of the main points about this standard is that it will give an objective measurement for exactly how long it takes certain materials to biodegrade to certain levels using certain additives. In other words, it's not so much a "standard" that must be measured up to as it is a spec to indicate that certain conditions are being met and certain results are being achieved.
I'm puzzled by engineering complaints about government having too many regulations - Look at the most profound organism we know - the human body. The mind, the physical system, the interplay of organs, tissues, fluids. Study human physiology and you will realize that there are no small/short/truncated control loops. Every bodily fact enters into setting up a new stasis. Was it Einstein who said "make things as simple as possible, and not one bit simpler"? that's what we should notice and complain about in this world - governments that imperfectly regulate for political and financial reasons and still end up missing the target.
Eat food that hasn't been subjected to sanitary regulations, fly, get operated on, have a new house built, buy a new car, take prescription drugs. Now tell me with a straight face that ALL are better off if government would back off and let good old blatant free-market capitalism rule the transaction. Much more efficiently.
I tire of hearing these slogans from engineers; we know better.
We're seeing an interesting regulatory and standards dynamic in the tech sector. On the political front, there's lots of talk about how regulations are an impediment to business and have to be dismantled. It seemed (or seems) to me that this movement is very powerful. Yet when I look at what's happening on the ground, engineering companies are having to become MORE compliant with stds and regs, not less. An illustrative case is that of equipment safety regulations. Because there are regs in place in Europe, with which US vendors selling globally have to comply, those regs apply de facto domestically.
William K, a good number of engineers would agree with your thoughts when it comes to the disposal of tin lead solder. They still complain there was no science behind the choice to ban the small amount of lead that keeps tin solder from growing whiskers.
Yuu are certainly correct in that there would need to be a fundamental change in the entire philosophy of handling waste. There is no question about that. BUT just because doing it one way is what everybody has been doing does not make it the right way or the smart way. There are lots of examples of poor choices being continued because nobody was willing to admit that the initial choice was poor. Ego is a terrible handicap.
The huge amount of waste entombed presently should serve to show that it was not the best choice. But those in charge can't see any other way.
@William: Actually, there is a class of biodegradable plastics, called oxobiodegradable, which are intended to break down under weathering conditions. They contain metal salts which are intended to speed up "normal" weathering. There are a few problems here: first, do they break down into something which is environmentally benign, or do you just wind up spreading hazardous organic chemicals far and wide? For example, if you broke polycarbonate back down into its monomer, you'd be converting a material which is relatively inert (bulk polycarbonate) into something which is thought to be an endocrine disruptor and possible carcinogen in humans and animals (Bisphenol A). Second, now that you've sped up "normal" weathering, will the material be able to perform as intended in the application? Third, as you've mentioned, there's a question of how to handle the waste to make sure it's exposed to UV rather than buried under a pile of trash. This seems like a simple problem, until you realize that you're talking about changing the way millions of tons of trash is processed. Finally, as with all biodegradable plastics, there's the problem of recycling (or, more accurately, making sure they don't get recycled).
Beth is definitely right that this is an extremely tough problem.
Here is an interesting consideration about the plastics scrap stream: Many of these plastics would break down if they were exposed to the sunlight and the related ultraviolet light. I have seen that happen. But embedding them in a dark and dry landfill assures that they will last a very long time. So perhaps thefundamental concept of currenbt landfills is deffective. OF course it would take a bit more effrt to get the pllastics to where they would be subject to weathering, but that might be better than encapsulating them for "all eternity" as a nasty legacy for those who follow us.
Really, it might be better to encourage landfill decomposition of the waste instead of assuring it's longevity. Part of that could include a bit more effort towards the separation of plastic materials, also the separation of metals. The fact is that the density of the base materials in landfill is much greater than their density in ores when mmetals are mined. The conversion of the plastic waste stream into a useable base should also wind up consuming less energy. With plastics, this could include solar energy which is sort of "free".
This is an interesting departure from previous generations of biodegradable plastics. The polyolefin-starch blends which came out in the early 1990s, which were the first plastics to be marketed as biodegradable, had many shortcomings. First of all, only the starch component was actually biodegradable, leaving the polyolefin component in the environment. So, from an environmental perspective, they were no better than non-biodegradable plastics (and probably worse, since the smaller fragments of polyolefin were more mobile in the environment). Second, the starch component would sometimes degrade in use, rendering the product unusable - and would stubbornly fail to degrade in landfills. Third, if they were introduced into recycling streams, the biodegradable plastics would degrade the properties of the recycled product. All of these disadvantages tended to give the term "biodegradable plastics" a bad name.
Since then, there have been several other attempts at making biodegradable plastics. Among them, compostable plastics based on polylactic acid have been fairly successful from a marketing perspective. One of the big selling points is that they are made from natural materials (corn oil); of course, whether or not converting food crops into disposible plastics in the midst of a global food crisis is a good idea is debatable, to say the least. These plastics are intended to be composted, not landfilled. Recyclers won't accept them, and keeping them out of recycling streams continues to be an issue.
The biodegradable plastics described in this article are interesting in that they are normal commodity plastics with additives to allow them to be degraded by anaerobic bacteria in landfills. This should address some of the issues with previous generations of biodegradable plastics. One issue which I didn't see addressed, however, was the question of recyclability. What happens if these additives make their way into recycled products? If these plastics need to be kept out of recycling streams, how do you train environmentally-conscious consumers - who have learned that recycling plastics is the responsible thing to do - not to recycle them?
Another issue - brought up in the press release - is emissions. Perversely, one virtue of non-biodegradable plastics is that, since they don't break down, the carbon contained in them is effectively sequestered. Biodegradation of plastics releases carbon dioxide and methane, which are greenhouse gases. The press release mentions that the methane could potentially be captured and used as fuel, but either way, you are putting carbon in the atmosphere which otherwise wouldn't be there. It would be interesting to see a full life cycle analysis of this.
Another interesting twist is the fact that it's illegal in California to label any plastic product as "biodegradable." It would be interesting to see whether plastics with these additives might be able to get past this ban.
I think everyone agrees that reducing the volume of plastics in landfills would be a good thing. However, it remains to be seen whether biodegradable plastics are a good way to achieve this, or if the formula of reduce, reuse, and recycle is a better path.
Any kind of technology, material, or standard that could put a dent in the 29 million tons of nonrecyled plastics in landfills would be a really important deal. I'm just hoping that such a standard wouldn't get stymied or watered down by the usual standards-setting process or any of the politics that's likely to ensue. This kind of thing is too important to be tripped up by such machinations.
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