plastics 101

“Every little piece of plastic manufactured in the past 50 years that made it into the ocean is still out there somewhere.” Tony Andrady

In 2012, 288,000,000 kilograms of plastic was produced, of which the large amount ends up in the ocean. While most people recognize the need for this level of wastage to stop, the true extent of damage being done is hard to grasp.

Through ocean currents, plastic aggregates at certain spots in (gyres) covering huge areas. To put this in perspective: today we have plastic „islands“ greater in size than Europe floating around in our marine ecosystem. This is not only a problem for marine species, since the large plastic parts are broken down into tiny portions of plastic (through corrosion,UV light etc.) which are inevitably consumed by something which we eat. The higher in the food chain an organism is, the more toxins he consumes (e.g. assume we have 0.1 g toxin per prey, the predator has to eat 10 times as much as the prey does to survive, and so he would end up with 1g of toxin).

Since humans are the top predator on the planet, you can extrapolate what that means in terms of the accumulation of toxins.

So the question is how can we attempt to solve these problems?

First of we can reduce the amount of plastic produced by banning of one-way-plastic bags , or visiting stores that sell without packaging, but these options only try to limit the damage being done, not solve existing damage.

We have to find an alternative with similar properties, which does not take roughly 400 years to break down, and which can be produced from renewable sources (unlike conventional plastics, which are produced from oil). Additionally, this ndw source has to be nontoxic and economically viable with regard to its production costs.

One solutions could be Polyhydroxybutyrate (PHB). It is biodegradable, nontoxic, and not water-soluble. Additionally, it offers similar properties compared to conventional plastics (polypropylene).

mike 1
Production occurs through bacteria, namely E.Coli and Ralstonia eutropha. If these bacteria are cultivated with a surplus of a carbon and deficit of P, S, O2, Fe, or Mg, PHB accumulates in the cells.

At the end of the fermentation, the broth consists of water, salts, and “bio-factory” cells.

E. coli (K12) is seen above filled with plastic, at up to 90% of their dry weight.

After that process, the bacteria are dried and cut open (disruption of cell integrity). The raw PHB can now be extracted and processed.

(1. bacterial supspension 2. dried bacteria 3.raw-PHB 4.-6. processing to spherical granulate)

This biopolymer is already being used by Toyota, in their Prius car.

There are also efforts successfully creating plastic from mold.

turtleplasticConclusively we have to solve three essential problems in our plastic usage culture:

1. We have to find alternative renewable sources (e.g. PHB)

2. We have to clean up the damage that has already been done.

3. And finally, simply reduce our present consumption rates as much as possible.