Recirculation of Plastics

Tiistai 20.11.2018 klo 15.32 - Mikko Nikinmaa

A huge problem has been generated for most Western countries. China has stopped importing any plastic waste. Exporting plastics for reuse in China has been the way most West European and North American countries have got rid of accumulated plastics. While much of the plastic waste has been reused in plastic toys and such like, some of it has ended up in the huge amount of plastics in the ocean near China. In principle the reuse in, e.g., plastic toys is a good way of getting rid of plastic waste, but one should be able to ascertain that all the waste is going for the intended purpose and not ending up in oceans. One thing is that plastic waste should be clean and uniform. Earlier on one did not care if plastics had toxic components, since they were thrown away anyway (one did not care that the toxicant ended up in the environment). However, recycling of plastics requires that the new products made are not toxic. Also, people sorting the plastics should not be exposed to the toxicants. The need for toxicants in plastics has actually disappeared making large-scale sorting feasible. It can be done more and more automatically - and should be done, if not in China then in the places of origin.

Can we get rid of plastics - or is it really needed?

Lauantai 20.1.2018 klo 13.08 - Mikko Nikinmaa

When I was a child there was practically no plastic material. Fruit and other foods were placed in paper bags. Water was carried in metal buckets. Now everything is put is plastics - all the clothes are in plastic covers, candies are first in plastic bags and then in individual plastic covers. It can actually be said that we have moved from iron age to plastic age. Plastics are oil-based, cheap, light and durable materials. Further, they are good insulating material. Therefore, when I look around, covers of computers, printers, TVs, phones etc. are made of plastics. The same is true of wastewater pipes. For this reason, replacing plastics in manufacturing is very challenging. Or is it really needed?

The real problem with plastic waste is the material that is thrown in the environment. That is the material generating the big marine garbage gyres. Most of their material is plastic waste thrown to the environment. It is funny that people picknicking in parks do not collect their plastic cups, plates and utensils and put them in garbage bins. If that were always done - all the plastic wastes placed in the collected carbage, there would not be any garbage gyres, and the sea and the coasts would be beautiful and trash-free. I have sometimes wondered if people, who throw the wastes around in the environment do that also in their homes.

So what to do with the plastics? The first thing is that they have to be collected. Thereafter much could be recycled, used for new plastic products. Currently only a few percent of plastics are recycled largely because recycling containers are quite rare. If societies really want to solve the plastics pollution problem, the collection of plastics must be improved - the percentage of plastics that is recycled  could easily be increased to over 50%. For the rest, energy use is probably the best. Since plastics are made of oil, burning them for heat production of towns instead of oil, which continues to be used for a long period of time, would be advisable. Instead of burning oil, one could first carry shoppings home in a plastic bag, thereafter use the bag in collecting trash, whereafter it would be burned. Since the same material would be used for several times, the carbon dioxide footprint of the bag would become smaller. This is more or less the same as instead of using wood to produce energy, it is used to produce paper for a newspaper which is afterwards burned in a fireplace.

If plastics were either recycled or burned for energy production, most of plastic pollution would disappear. The remaining problem would be microplastics. Much of it, which is caused by the slow breakdown of big plastic materials to microplastics as a result of mechanic tear, solar radiation and oxygen, would disappear with the collection of plastics. The remaining sources are plastic microbeads of cleaning liquids, tooth pastes and cosmetics, the small fibres given up whe washing clothing containing synthetic materials, and the dust from tyres, paved roads, artificial turfs etc. The first of these could be avoided already today, since there are more and more products, which do not contain plastic microbeads. The choice is the consumer's: he/she only needs to read the contents or ask the shop assistant, and buy products without plastic beads - if products with plastic beads were left unsold, the manufacturer would soon change their contents.The fibres from washing clothes containing synthetic materials is a more difficult problem, as most pieces of clothing have some synthetic fibres. Fleece clothing has recently gained a lot of attention, but actually most shirts, trousers, Goretex clothing, other outdoor apparel  etc. contain synthetic material, and are thus a source of microplastics. The problem with replacing clothing with synthetic materials by cotton actually causes as big environmental (and social) problems as it solves. Water and pesticide  use of cotton production is unacceptable. Further, the use of child labour in different stages of making cotton clothing is also unacceptable. The third major source of microplastics: the tear of tyres, dust from roads, and dust from artificial turfs is probably quantitatively the most important. There are no easy ways to decrease the amount released from traffic, unless people give up cars, and use rail traffic instead.

Thus, I think that the use of plastics can continue, if measures are taken not to allow the release of plastics to the environment. For a large part this can already be done, but requires actions both from the consumers and the society.

Plastics removal by micro-organisms

Sunnuntai 24.9.2017 klo 17.50 - Mikko Nikinma

Plastic garbage is a huge problem everywhere in the world. The most visible collections of mainly plastic trash are the Pacific Garbage Gyre and similar smaller ones in the Atlantic and Indian Oceans, but all the aquatic environments have plastic waste and non-visible microplastics. Plastic trash is a highly visible problem also in terrestrial environments.

In the light of the huge plastic pollution problem, two major solutions to alleviate it have been envisioned. The first involves diminishing the use of plastics markedly, collecting plastic trash for reuse, and if the material cannot be reused, burning it. Burning plastic is virtually the same as burning oil, since currently virtually all plastics are made of oil. Thus, burning the plastic trash diminishes the need for oil and thus diminishes its consumption. This way of addressing the plastics problem is tedious, demands a lot of work and time, and requires a change in our daily behaviour. 

The other solution is much simpler. Let's just find a micro-organism, which uses the plastics as an energy source. The evolution of micro-organisms is rapid as a result of their short generation interval. There are both some bacteria which use oil as food and some fungi which decompose plastics. An example of the latter has recently been described in the journal Environmental Pollution (Khan et al. 2017 Environmental Pollution 225, 469-480). Notably, oil-eating bacteria have successfully been used to clean up oil-contaminated soil, so what is simply needed is to have plastic-eating micro-organism placed within plastic trash, and the microbe does the rest. Simple and effective, right?

However, the solution is not so clearcut beneficial. Our world today uses plastics in virtually everything. Already in the beginning of 1972 a book with the name Mutant 59: The Plastic Eaters was written by Kit Pedler and Gerry Davis. In the book, a mutant bacterium was generated (to remove plastic contamination), but it got loose and started eating up, e.g., the plastic covers of electrical wires with the consequence that electrical appliances short-circuited, planes crashed etc. No one can guarantee that the plastic eating micro-organism cannot spread outside of where it is wanted, unless the evolution of organism is directed so that it cannot live anywhere but its wanted target. For example, one could generate the plastic-eating micro-organism so that it is strictly anaerobic, whereby it would die immediately upon contact with air.

However, for developing the plastic-eating anaerobic organism time is needed. Thus, we must primarily use the tedious first alternative.