Household biodegradable plastics

plastics
Originally uploaded by Lenny & Meriel.

Whether or not it's hard work we have an avenue for disposing of most regular household waste without resorting to landfill...

• Glass - recycle
• Tins - recycle
• Cans - recycle
• PET 1,2 plastics - recycle
• Paper - recycle
• Card - recycle
• Vegetable matter - compost
• Waste food (apart from vegetable matter) - wormery or bokashi

Most of what's left in my bin (and most others I believe) is other sorts of plastics including a lot of polythene and plastic food trays. One solution is that we all avoid buying food and other goods packaged in this way - that would be quite a challenge! Manufacturers use it for good reason - it's strong, lightweight, cheap to produce, waterproof, mouldable and printable and it lasts forever. The latter is of course a large part of the problem: 90% of all the plastics ever produced still exist - they simply won't go away - and yet we keep making more and more which draws upon the diminishing supplies of petrochemicals.

We could start recycling it - but that's not generally accepted as being a worthwhile exercise once you factor in the envionmental costs associated with transportation and processing.

Technology does exist to replace all of this with degradable or biodegradable equivalents which would allow us to place the waste straight on the compost heap. All the different technologies seem to have ways to speed up or slow down the decaying process dependent on the context of use making it ideal for food packaging. It would in theory release nothing but water, CO2 and biomass. Trawling through the web (I'm no scientist) it appears there are 4 ways to make biodegradable and degradable plastics:

1. Biodegradable: Starches from cereal and tuber crops are harvested then broken down by microorganisms into monomers which are then chemically 'rebuilt' in a longer form of polymer which forms the basis forpolylactide (PLA). This is an expensive process for the production of a very low value material.
2. Biodegradable: Bacteria can also produce polyhydroxyalkanoate (PHA) and polyhydroxybutyrate (PHB) directly by themselves in a culture which then simply needs to be harvested.
3. Biodegradable: Combining the last 2 principles, the same crops can be genetically modified by introducing the gene from bacteria into the plant to producePHA and PHB . Genetic modification does not have public support and there are doubts about the ability to stop modifications reaching crops grown for consumption.
4. Degradable: plastics such as d2w are made using a traditional plastics process with additives to break down the polymers over time - The manufacturing process is one which involves petrochemicals as now but the advantage of this technology is that the plastics do not require expoure to organisms to break down - they will break down in any environment including landfill and on the streets.

All are contraversial in their own ways involving one or more of the following issues:

• Continued reliance on petrochemicals for degradable plastics Nb. Even some biodegradable plastics have a petrochemical component to improve the quality of the plastics.
• Production process cost making them uncompetitive (2 to 10 times as much) when compared with traditional plastics. Nb. this is improving as petrochemical prices go up making traditional plastics cost more. This cost does not truly represent the lifetime costs because the end of life transportation and disposal is removed from the calculation. If business were exposed to this aspect, and did factor it back in, things might look more comparable.
• Genetic modification is not popular because of concerns regarding the effect on crops grown for consumption.
• Production lines are already set up to cope with current technologies and plastics. Any replacement must function on the same lines and therefore perform in a very similar way. nb. Some of the products available do claim to offer this.
• The current situation leads to excessive landfill which is not considered a high priority to resolve as attention is placed on items which release greenhouse gases when placed in landfill. If plastics become biodegradable a different consumer behaviour will be necessary to avoid making the problem even worse!

I believe that the technologists will find a way through this and arrive at a degradable plastic which has all the positive properties associated with traditional plastics at a competitive cost. Hopefully this will function as well on both the domestic compost heap as in landfill. This does offer up a whole world of potential for improving the consumer experience - here are a few thoughts.

CHALLENGES

• The plastics are often messy having been in direct contact with food - managing them and storing them is an unpleasant experience. The temptation is to 'get rid of them' by putting them into the bin.
• They are bulky by their nature - they are often moulded to retain structure. People need encouragement to store them alongside all the other recycling
• Domestic compost heaps function best when everything breaks down in approximately the same amount of time. The presence of larger items such as plastics might slow this down and make it harder to aerate / turn the heap.
• The change will not be sudden - as a consumer I'll need to be able to easily (yes I mean easily) identify which plastics can be composted.

SOLUTIONS (anything goes - this is brainstorming)

• Make them instantly recognisable and use this as a marketing benefit. E.g. The plastic is always green or always has a leaf (or seeds) embedded into it / printed onto it.
• Embed a tagging mechanism so that packaging can be electronically identified and processed accordingly (either within household through the use of intelligent bins or in a central facility). This could apply to all packaging (not just plastics).
• Use such a mechanism to monitor trends and to let people monitor their own habits - perhaps even incentivise them by giving credits against recycled goods to encourage that market place.
• Market cheap shredders which can handle paper and plastics (including messy polythene) for household use. This would enable householders to store it more effectively and then encourage faster and more 'turnable' composting.
• Provide similarly degradable bags which are airtight even when still being filled up to avoid odours from any food remains. These could be used for all compostable household waste.
• Integrate a datestamp mechanism into the plastic. As it will decay in a preset amount of time - perhaps this can also be a visual reference to the age of the goods and the stage of decomposition - e.g. a colour change, line clarity etc. This is a bit like colour indicator toothbrushes which let you know it's time to get a new one.
• Impregnate the container bag with Ems (Effective micro-organisms) to encourage faster decomposition once on a compost heap.
• Charge people for anything taken to landfill, make recycling free