Have you noticed the different new "green" bags in your supermarket or grocer? They claim to be 100 percent komposterbar og biologisk nedbrytbar.
De fleste av dem er laget av PLA, en bioplast. Bioplast er en ny type plast som vanligvis er laget av plantestivelse eller sukker, og ikke fra petroleum. Å ha navnet BIO i plasten kan være litt misvisende siden de ikke bare brytes ned som et bananskall.
Så er PLA virkelig komposterbart?
The short answer is YES! But the plastic is only compostable if you bring it to an industrial composting facility that accepts PLA plastic, and there aren't that many.
La oss ta en titt på definisjonen.
1. Biodegrade – break down into carbon dioxide, water, biomass at the same rate as cellulose (paper).
2. Disintegrate – the material is indistinguishable in the compost, that it is not visible and needs to be screened out.
3. Eco-toxicity – biodegradation does not produce any toxic material, and the compost can support plant growth.
Biodegradable Plastic is plastic which will degrade from the action of naturally occurring microorganism, such as bacteria, fungi, etc. over some time. Note that there is no requirement for leaving "no toxic residue," and as well as no requirement for the time it needs to take to biodegrade. This can actually take between 100 – 1000 years. Not helping the environment at all.
Degradable Plastic is plastic which will undergo a significant change in its chemical structure under specific environmental conditions resulting in a loss of some properties. Please note that there is no requirement that the plastic has to degrade from the action of "naturally occurring microorganism" or any of the other criteria required for compostable plastics. A plastic, therefore, may be degradable but not biodegradable, or it may be biodegradable but not compostable (that is, it breaks down too slowly to be called compostable or leaves toxic residue).
Hva er PLA?
PLA or Polylactic Acid is mainly made from genetisk modifisert cornstarch, which is so kindly being produced by NatureWorks, a subsidiary company from Cargill, the biggest producer of modified corn in the world.
PLA er laget av en "fornybar" ressurs, ikke petroleum, og når den forbrennes, vil den bare etterlate karbondioksid og vann. Det er gode nyheter, ikke sant???
BUTIt requires an industrial composting facility where a cocktail of microorganisms is continually being fed, and a temperature of 60 C is required for 10 days. It also needs the right amount of moisture and oxygen to degrade in 3 – 6 months.
In a properly engineered landfill, nothing is meant to degrade. No bag – reusable or conventional plastic shopping bag – will decompose in a landfill. Which actually helps the environment by not producing dangerous greenhouse gases like methane.
In fact, your compost wouldn't even get to the desired temperature of 60 degrees Celcius or 140 Fahrenheit. The standard home compost reaches a maximum of 43- 48 C, or 110 – 120 F.
It is not recommended to put these PLA biodegradable plastics into your home compost, they might remain there for 100 – 1000 years.
Hvor blir min "PLA biologisk nedbrytbare plastpose" av?
You probably think you are doing a good thing for the environment by buying a green bag that claims to be biologisk nedbrytbar og komposterbar.
Rett nok får selskapene dem til å se grønne og trivelige ut, og reklamen er rett og slett misvisende. Ja, de brytes ned, men bare på et industrielt komposteringsanlegg. I USA er det bare 113 av dem.
See if you can find one in your area by going to find a komposter.
Jeg er for tiden bosatt i Quebec, og jeg fant 2 fasiliteter i hele Quebec-provinsen. TO fasiliteter for hele Quebec-provinsen???
Vårt lokale Metro Supermarked deler ut 15 000 plastposer per uke, og det inkluderer ikke frukt- og grønnsaksposene. Hvem kan håndtere disse avfallsmengdene?
The other problem we find with PLA is, people often think it is recyclable, just like our standard plastic, and therefore it ends up in the same bin. This misconception causes lots of problems in the plastic recycling world as your PLA products to act as a contaminant in hydrocarbon-based resins such as PE, PP, PET, and PS.
It costs millions each year for recycling facilities to sort through the different plastics since PLA looks very similar to standard plastic, and the machines can't identify the difference yet.
Hva er alternativet?
So far, the best solution we have is to minimize our use of single-use plastics overall. Bring your green shopping bag to the grocer, and if you like using straws, consider swapping to naturens halm.
Her er noen flere tips for å minimere bruken av-engangsplast.
We don't have a way to dispose of PLA products properly. Buying items that are not heavily packaged in plastic is a good alternative. We have to become aware of the fact that most bioplastics aren't good for the environment either.
La oss hjelpe og spre ordet. Vi vet at det finnes alternativer der ute, mesteparten av tiden er det bare et spørsmål om å utdanne deg selv og vennene dine til å ta bedre avgjørelser. Jeg håper du kan gå bort fra denne artikkelen med litt mer kunnskap om forskjellige typer plast.