Recycling Plastic Waste

Perjantai 14.10.2022 klo 15:16 - Nikk Nikinmaa

One of the biggest problems with recycling plastic waste has been that a mixture of different plastics cannot be used as a feedstock for generating new plastic products. This means that either the consumers have to be quite careful and knowledgeable in sorting plastics or recycling stations need to carry out expensive sorting of plastics for further use. In a recent article in Science (October 13, 2022; DOI: 10.1126/science.abo4626) Sullivan et al. present a method that can be used for a mixture of plastics to generate starting material for commercial use. The method is comprised of two steps: first oxidizing the plastic mixture with metal-based catalysis (Co and Mn) to intermediates that can be digested by engineered bacteria to produce a feedstock for new commercial products. By varying the way that the bacteria are engineered, different starting products can be generated.

To my eyes, this method is quite safe and practical. It avoids the inherent problem with plastic-eating bacteria. I remember the book Mutant 59 by Kid Pedler and Gerry Davis (from 1971) where the plastic waste was planned to be eaten by bacterial mutation, which was very effective in consuming plastics, favoring them over any other foodstuff. The mutant naturally got accidentally free and started devouring everything made of plastics. Planes started crashing down, because all the plastics covering electric leads were eaten up and motors short-circuited. Most things in our houses became non-functional or half-disappeared etc., naturally, if you look around: most things are at least partly made of plastics. Since in the method described by Sullivan et al. the engineered bacteria eat only the oxidized end product of catalysis, they can only live in the recycling plant. By combining this method with effective collection of plastic waste, much of the plastics problem can be removed.

However, even if we get smokers to put their cigarette butts to waste bins, there will be one significant source of small plastic particles. Almost half of the microplastics in the environment is tire wear particles. They are impossible to collect. Thus, even if the recycling of all other plastics were more than 90% successful, this source would remain. It can only be reduced by drastically reducing road traffic. In this regard, electric cars are not a solution, the only solution could be using rail traffic and public transport more generally.  

 

Kommentoi kirjoitusta. Avainsanat: waste collection, tire wear, cigarette butts, waste treatment

The plastics problem - are there any solutions?

Sunnuntai 10.6.2018 klo 11:59 - Mikko Nikinmaa

The news about plastic pollution has more or less completely dwelled on the problem, and not much on solutions apart from one: banning the use of plastics. And, unfortunately, most of the news has reached North Americans and Europeans. I say that this is unfortunate, since even if the plastics in North America and Europe were recycled 100 %, this would have hardly any effect on the total amount of plastic waste entering the oceans. There are ten rivers in the world, which deliver most waste to the oceans: three in China, one in Philippines, one in Indonesia, two in Indian subcontinent, one in Brazil and two in Nigeria. Out of the 40 most plastic-polluting rivers 27 are in Asia,  8 in Latin America, 4 in Africa and 1 in Europe (Rhine).

Thus, the most urgent problem is to get waste treatment in the most polluting areas to function. A solution for this would be, if money could be made out of it. A possible way of doing this would be portable systems, Trashpressos (as named by the inventor, Arthur Huang), which press plastic waste to strong tiles, which could then be used in, for example, building houses. In this way, what is now thrown away would markedly reduce the costs of building material - which would be highly beneficial for developing nations.

A way to decrease plastic pollution everywhere is to use materials other than plastics whenever possible and convenient, diminish unnecessary wrappings (nowadays it is possible that, e.g. candies are in plastic bag, and thereafter individually wrapped in plastic) and stop using single-use plastic materials (instead of plastic single-use knives and forks one could have them made of wood as earlier; plastic cups could easily be replaced by paper cups or glasses) - the European Union ban on single-use plastics will certainly drive production and use also elsewhere.

With regards to microplastics, which is a problem also in Europe, the ways of diminishing plastic waste will help in part. However, much of the microplastics is released in washing clothes. In Europe and North America this waste comes into wastewater treatment plants. If the final effluent were filtered through a tight-mesh filter, all of the microplastic waste would be retained. Since the effluent goes through a narrow pipe in any case, this would not even cause a big expense. Such a simple solution would decrease the problem of microplastics release from clothwashing. Another problem is cigarrette buts, which people throw on the ground all the time. Instead, people should put them in waste boxes. This is already now possible, so it is only a matter of educating people. The only source of microplastics that I have not been able to think a reasonable way of getting rid of is the tyre dust. Presently, much of the tyre material is plastics, and is released in the environment. Such dust cannot easily be collected.

However, most of the plastics problem could easily be handled without needing to stop the use of plastic materials in appliances, where they are needed or much better than alternative materials. 

Kommentoi kirjoitusta. Avainsanat: plastic pollution, waste treatment, garbage gyre

Waste management - the key to reduce plastic pollution

Maanantai 12.3.2018 klo 13:46 - Mikko Nikinmaa

Everyone has seen pictures about garbage gyres, composed mostlGarbage_gyre.jpgy of plastics but also all the other kinds of our waste. As a result of these pictures and different videos about encountering plastics all the time when diving, it has become very fashionable to demand that we get rid of plastics. In Finland "Muoviton Maaliskuu" (March without Plastics) is getting attention. However, is it really so that the lightweight, durable and easily molded material is the evil of all evils?

It is funny that I have now in several instances sounded like an advocate of plastic industry, although I really think that the slogan should be "environment first". It is clearly so that the plastics problem cannot be resolved by removing the material from the oceans after it is there. The migitation must take place before. There are two ways of doing this: 1. Stop producing and using plastics. Although there are many instances, where the use of plastics is not necessary, why should one stop using very useful material? 2. Stop the plastic waste from entering aquatic environment. I think this is the real possibility, as hopefully becomes clear from the following text.

In their article in Science in 2015 Jambeck et al. (Science 347, 768-771), estimated, where the plastics to the oceans come from. Interestingly, among the 20 most plastic-polluting countries, there was not a single European country, although the use of plastics per capita is among highest in the world (If considered as one entity, European Union, with twice the population of USA, would have been no. 18, slightly ahead of Morocco, North Korea and USA). Out of the 20 countries producing most mismanaged plastic waste 8 were from  Pacific Asia (China, Philippines, Indonesia, Vietnam, Thailand, Burma, Malaysia, North Korea), 4 from Indian subcontinent (India, Pakistan, Bangla Desh, Sri Lanka), 5 from Africa (Algeria, Egypt, Morocco, South Africa, Nigeria), The remaining three countries were Turkey, Brasil and USA. It is notable that there appeared to be more mismanaged plastic waste coming to the oceans from North Korea than from USA. It is also notable that Japan and South Korea were not among the most plastic-polluting countries.

So what is the reason of the plastic waste in the oceans. It is not plastic use per person, which is highest in USA, Canada and European countries. It is poor waste management. In USA only a couple of % of the plastic waste enters the ocean, most of the waste is burned and some recycled. In Europe the situation is similar. In the Pacific Asian countries in the list 80 % of the waste is not treated properly. The mismanaged plastic waste of Indian subcontinent countries exceeds 85 %, and that of the African countries is slightly over 65 %. Consequently, if waste management in the primary polluters could be improved to European/American level, the amount of plastic waste reaching the oceans would decrease to 1/30-1/40 of what it is today. If we, in addition, decreased the unnecessary use of plastics, the good material could be used without generating the unfounded guilty feelings.

Together with climate change actions, i feel that waste management issues should assume major emphasis in environmental negotiations. Further, effective waste management (in the simplest case burning) is not the question of money but attitudes, so it could be done as easily in poor as in rich countries.

Kommentoi kirjoitusta. Avainsanat: plastic waste, garbage gyre, waste treatment

Getting rid of garbage gyres - its not plastics but people's attitude

Sunnuntai 11.3.2018 klo 11:52 - Mikko Nikinmaa

The waste in the seas and also in the terrestrial environment is without doubt a big problem. In this one has taken plastics as something that is the evil. Plastics are undoubtedly a problem, because they are highly stable and, being light, float and are thus easily seen. However, plastics are not the only stable pieces of trash. Similarly, all the metal-made products last almost to eternity. For plasticts to be an environmental problem, they need to reach the environment. If they did not, they would not be a part of the environmental problem.

Plastics are usually made of oil. We are still currently warming up a lot of houses with oil. If all the plastics were collected as part of the waste and burned to produce energy, no plastic waste would be generated and the need for oil would decrease. Is this done in most parts of the world? No, in the best case the plastic waste is a part of the waste ending up in waste dumps, where it is virtually eternal, and in the worst case barges filled with waste are tugged out to the open sea, where the waste is just dumped to the water. Out of sight out of mind. However, this being the case, it is actually wrong to blame a set of good products for generating a problem, when the problem is in our way of waste handling. Further, if the plastics were effectively collected, most of them could be recycled, obliviaing the need of producing new plastics to be thrown away.

Undoubtedly, there is much unnecessary use of plastic materials, and thus, plastic production can be radically diminished. However, there will always be a need for a light-weight, durable material for various appliances. And different plastics are just that, and they can be either recycled or disposed by burning so that no waste is generated. So the real problem is not the plastics, but our way of treating waste. The environment should not receive any permanent waste. People should stop throwing waste, but instead collect it all and either recycle or burn. In addition to plastics, another big permanent source of waste is metals. If they were not thrown in the environment bt recycled, the need for mining with all its environmental problems would markedly decrease.

Kommentoi kirjoitusta. Avainsanat: plastic pollution, waste treatment, garbage dumps