Tel Aviv scientists produce bioplastics from seaweed
Scientists with Tel Aviv University have developed a new method for producing biodegradable polymers that don't require fresh water or plants. The technology paves the way for future biodegradable, sustainable plastics that don't use up vital — and increasingly limited — resources while also addressing the most pervasive pollutants. The polymer is derived from microorganisms that feed on seaweed.
It is biodegradable, produces zero toxic waste and recycles into organic waste. The invention was the fruit of a multidisciplinary collaboration between Dr. Alexander Golberg of TAU's Porter School of Environmental and Earth Sciences and Prof. Michael Gozin of TAU's School of Chemistry. Their research was recently published in the journal Bioresource Technology. According to the United Nations, plastic accounts for up to 90% of all the pollutants in our oceans, yet there are few comparable, environmentally friendly alternatives to the material. A partial solution to the plastic epidemic is bioplastics, which don't use petroleum and degrade quickly. But bioplastics also have an environmental price: To grow the plants or the bacteria to make the plastic requires fertile soil and fresh water, which many countries, including Israel, don't have.
The new process produces 'plastic' from marine microorganisms that completely recycle into organic waste. The researchers harnessed microorganisms that feed on seaweed to produce a bioplastic polymer called polyhydroxyalkanoate (PHA). “Our raw material was multicellular seaweed, cultivated in the sea,” Dr. Golbergsays. “These algae were eaten by single celled microorganisms, which also grow in very salty water and produce a polymer that can be used to make bioplastic. “There are already factories that produce this type of bioplastic in commercial quantities, but they use plants that require agricultural land and fresh water. The process we propose will enable countries with a shortage of fresh water, such as Israel, China and India, to switch from petroleum derived plastics to biodegradable plastics.” According to Dr. Golberg, the new study could revolutionize the world's efforts to clean the oceans, without affecting arable land and without using fresh water. “Plastic from fossil sources is one of the most polluting factors in the oceans,” he says.
“We have proved it is possible to produce bioplastic completely based on marine resources in a process that is friendly both to the environment and to its residents. “We are now conducting basic research to find the best bacteria and algae that would be most suitable for producing polymers for bioplastics with different properties,” he concludes. The new bioplastic polymer technology, which was recently detailed in the journal Bioresource Technology, addresses both of those issues by producing a biodegradable product that is recycled into organic waste with no toxic byproduct.
UK start-up Teysha Technologies claims bioplastics breakthrough
Teysha Technologies Ltd, a London-based bioplastics startup, claims to have developed a breakthrough technology to develop organic-based plastic substitute. The company said its “plug-and-play” process take monomers and co-monomers from bio-based feedstock, such as starches and agricultural waste, to produce biopolymers that can be used in a large variety of applications.
Particularly, what makes the Teysha technology stand out is that it allows the company to “precisely tune the physical, mechanical and chemical properties” of its polymers.
“In doing so, we can adjust the strength, toughness, durability and longevity of our polymers to suit different applications,” according to Matthew Stone, commercialisation director of Teysha Technologies.
The “tunability” of the technology will allow for the manufacture of a wide variety of final products, from medical implants and vehicle moulding to food packaging and even cladding for building construction.
Teysha claims that its technology can produce bio-polycarbonate materials that are rigid or flexible, or that offer different thermal properties.
The process uses polyhydroxyl natural products as monomeric building blocks and carbonates as the linkages to produce the polycarbonates.
Crucially, the company asserts that it can control the biodegradation of its polymers – i.e. either within weeks or years.
Teysha maintains that its materials are fully compatible with existing production methods and that they “slots easily” into current manufacturing facilities.
Promising bioplastic-PEF derived from Sewage
A scientific group led by Baozhong Zhang, associate professor at Lund University's Centre for Analysis and Synthesis, has developed a “green” bio-polyester more durable than ordinary plastic and better suitable for recycling. According to lab experiments, it is more durable than both regular plastic and other bioplastics, and is potentially better suited for recycling.
Ping Wang (Photo: Theo Hagman-Rogowski)
Almost all plastic is made from crude oil, and plastic production currently accounts for 4-6% of global oil consumption. The development of renewable bioplastics is progressing, but relatively few are actually being used.
A strong candidate among bioplastics is polyethylene furanoate (PEF). Instead of oil, PEF contains the hydrocarbon, furan, which can be extracted from maize, wood and certain types of grain. The main market for PEF is packaging. Experiments have shown that PEF is superior to standard polyethylene terephthalate (PET) in protecting against oxygen, carbon dioxide and water, which gives products enclosed in plastic greater durability.
The success of PEF made researchers at Lund University interested in other renewable materials that could potentially be used for plastic production. Chemical engineering doctoral student Ping Wang has produced a plastic based on indole, a heavier hydrocarbon molecule than furan, that is present in human faeces and smells accordingly. The compound is also found in lower concentrations in certain flowering plants and has a more agreeable aroma. This effect is due to our sense of smell decoding the aroma differently depending on the amount and combination.
The research team is thought to be the only one researching indole polyesters, and their results are promising. A regular PET bottle's glass-liquid transition temperature – when the material softens and deforms – is 70 degrees. The most successful PEF experiments withstand about 86 degrees. However, one of Ping Wang's indole plastics is stable up to 99 degrees.
“These are preliminary results, but we have seen that polyester plastic has better mechanical properties, which makes it more sustainable. This can lead to better recycling in the future. At present, PET bottles can only be recycled once, then they must be used for something else such as textiles”, says associate professor Baozhong Zhang, who is supervising the research team.
Currently, indole is only produced on a small scale and used mainly in perfumes and drugs. It may be possible to use bioengineering methods to produce indole from sugar through fermentation. However, such a process would first need to be analysed more thoroughly before the production cost can be calculated.
Ping Wang is continuing her research by examining the indole plastic's potential in other application areas. “We obtained good results, but are not satisfied. Now we are trying to find methods for making higher quality indole polymers that can be used in more ways, not just for plastic bottles”, she concludes.
PHA from Sewage water produced at Sweden
The world's first PHA (Polyhydroxyalkanoates), from sewage water has been produced. PHA represents a truly groundbreaking innovation. Ina world first, PHA has been produced from bacteria that had first purified the wastewater treated at a full-scale wastewater treatment facility in Bath, located in the Dutch province of Zeeland, within the scope of an innovative project called PHARIO. The first kilo of PHA produced in this way was presented to Oerlemans Packaging director Joan Hanegraaf during a stakeholders conference hosted by the company in Genderen (NL).
PHAs are fully biodegradable plastics that, under normal conditions, will degrade within a relatively short period of time. PHAs are linear polyesters produced in nature by bacterial fermentation of sugar or lipids. They are made by bacteria to store carbon and energy, a function which in mammals is fulfilled by fat. These bioplastics are generating increasing interest, mainly because of their unique ability to biodegrade in water. As a result, the number of applications is starting to rise. However, the price of PHA has continued to be a major drawback: until now, the production of PHA has involved specially cultivated bacteria that fermented sugar, resulting in high production costs and, consequently, a reluctant market uptake.
The pilot project is a joint initiative of three Dutch water authorities Brabantse Delta, De Dommel and Wetterskip Fryslân, in collaboration with STOWA (Dutch Foundation for Applied Water Research), sludge treatment plant SNB, and two commercial parties, Veolia and KNN. Veolia Water Technologies is an international supplier of plants and services for communal and industrial wastewater treatment, and is participating in the project via its Swedish subsidiary AnoxKaldnes that, together with KNN, is contributing specialist knowhow and technology for the production of PHA. The partners in the project all contributed to the funding; in addition, the project was awarded a grant from the TKI Biobased Economy innovation program. The project is one of the most promising to come out of the Green Deal concluded in the Netherlands last year between the Dutch Water Authorities and the government.
Successful production – on a small scale
Currently, this extraction step is carried out in Sweden at the pilot plant of Veolia subsidiary and project partner AnoxKaldnes. Veolia holds a number of patents for the technology used here. The Cella technology developed by AnoxKaldnes works by creating the best possible process conditions for increasing the presence of biopolymer producing bacteria. The bioploymers are then harvested and further processed for industrial use. According to AnoxKaldnes, the processes “enable the recovery of value added renewable resources including biopolymers, lipids, minerals, other platform chemicals and energy as byproducts of process and wastewater management services.
This is the future of traditional Environmental Engineering.” Importantly, the PHA produced using the technology is clean and hygienic. Measures must be taken to ensure the quality is consistent and stable in this respect. The current project is intended to demonstrate the possibilities and the quality of PHA which the technology offers. As Martin Tietema, Director KNN Bioplastic commented: “PHA bioplastic enables us to develop innovative and biodegradable products with which we can fundamentally revise the way our society uses plastics.”
Ultimately, the aim is to establish value chains for PHA. While current production capacity is small – a few kilos per week – the idea is to scale this up to include the total treated wastewater volume and ultimately resulting in a production capacity of 2,000 metric tons/year. To that end, investment –and the commitment of stakeholders – are required to make it possible to scale up the technology and create a market for the PHA produced. This first batch shows the potential of the technology – and that it works.
Is biodegradable always environment-friendly?
Everyone these days is talking about plastic waste that, instead of being recycled, is floating in the world's seas. In many hip salad bars, for example, food is now available to take away in bowls made of bioplastics. Problem solved, right?
Wrong. There are bioplastics made from renewable raw materials, for example corn starch, and there are bioplastics that are biodegradable. This isn't the same thing. Not all plastics made from renewable raw materials, sometimes also known as "bio-based plastics," are biodegradable. And conversely, not all biodegradable plastics are made from renewable raw materials. Whether or not a plastic product is biodegradable depend not on the raw material, but on the chemical structure of the plastic.
It might sound rather complicated, but it's somehow logical: Because biodegradable plastic decomposes easily, it's not suitable for uses in which the plastic should be as durable as possible, for example water bottles. Researchers at ETH Zurich recently developed a bioplastic called polyethylene furanoate (PEF) that can be used in the same way as polyethylene terephthalate (PET) for water bottles. PEF consists of renewable raw materials and is, therefore, a step forward. It's recyclable or can be incinerated in a process that's CO2-neutral. But it's not biodegradable.
In fact, even "biodegradable" is not always biodegradable. For many of these plastics, it only works under certain conditions. For instance, the EN 13432 standard in use in Europe defines a material as "compostable" if, after 12 weeks in an industrial composting plant in which a certain temperature, humidity and oxygen levels are guaranteed, 90% of the material disintegrates into parts smaller than two millimeters. In other words, this won't necessarily happen in your home-made compost in your garden.
So far, there's no evidence that bioplastics degrade in seawater.
That's why many waste management companies in Germany — the ones in Munich and Berlin, for example — are not at all enthusiastic about the use of bioplastic bags in organic waste bins. In most cities, organic waste is composted for three months only. This is enough to produce fertile humus, but not enough to decompose these bioplastic bags. For this reason, the companies tediously have to sort the bags out. Instead, they recommend you wrap the organic waste in newspaper. The paper absorbs part of the liquid and is good for compost anyway because it loosens it up.
As for the plastic in the oceans, bioplastics wouldn't make much of a difference. The scientific arm of the German parliament has studied the question and wrote in a report that, so far, there's no evidence that bioplastics degrade in seawater. It must, therefore, be assumed that just like other plastics, they only decompose into ever smaller particles and become microplastics, but don't actually disintegrate. And even if the production of degradable plastics were to increase, it would "hardly contribute to reducing the amount of waste from the oceans," the report reads.
It gets worse. Germany's Federal Environment Agency takes a very critical view even of plastics made from renewable raw materials. Why? Well, because, ironically, the production of bioplastics from corn, potatoes or sugar cane still requires crude oil, for example for the production of fertilizer and as fuel for tractors.
The cultivation itself doesn't tend to be organic either, given the use of pesticides, not to mention the usual — at first invisible — side effects, such as too much nitrate in the groundwater. Genetically modified organisms are also often used. And the fact that corn or potatoes are basically used to process food into plastic is also questionable in itself. Bioplastics from forestry and agricultural waste such as sawdust or orange peels are better. In many cases, however, consumers will hardly be able to tell what the plastic they're using is made of.
The more often you use something, the less important it becomes which material it's made of.
Bioplastics are also more and more often used to make toys. Of course, wooden toys are preferable but some things simply can't be made with wood. And if children put bioplastic toys in their mouths, it certainly is less harmful than if they did it with cheap products made from crude oil, isn't it? Well, not necessarily.
Bioplastic toys are indeed a trend. Lego, for example, no longer wants to use crude oil for its bricks, but sustainable, renewable raw materials instead, which always looks good on the packaging. But even if the raw materials are produced sustainably, in order to make bioplastics resistant and flexible, the same chemical additives are required as for traditional plastics made from crude oil. And nobody has yet researched how dangerous these additives are.
Still, this doesn't mean you can't do anything right. There is, at least, one rule of thumb you can follow: The more often you use something, the less important it becomes which material it's made of. Plastic toys, even from the "wrong" kind of plastic, can be passed on among friends.
When shopping in the supermarket, you shouldn't take a new bag because in almost every household, there's the famous "bag with the bags inside" from which you can help yourself. You probably also have a cotton shopping bag lying somewhere. Always have such a bag folded up with you in case you go shopping spontaneously. Prepared in this way, you won't need a bag from the supermarket, at least not in the foreseeable future. And with a little preparation the previous evening, you won't even need any disposable crockery from the salad bar.
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