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For the first time, researchers have used bacteria to “upcycle” waste polyethylene: Move over Spider-Man: Researchers at Rensselaer Polytechnic Institute have developed a strain of bacteria that can turn plastic waste into a biodegradable spider silk with multiple uses.

Their new study marks the first time scientists have used bacteria to transform polyethylene plastic — the kind used in many single-use items — into a high-value protein product.

That product, which the researchers call “bio-inspired spider silk” because of its similarity to the silk spiders use to spin their webs, has applications in textiles, cosmetics, and even medicine.

“Spider silk is nature’s Kevlar,” said Helen Zha, Ph.D., an assistant professor of chemical and biological engineering and one of the RPI researchers leading the project. “It can be nearly as strong as steel under tension. However, it’s six times less dense than steel, so it’s very lightweight. As a bioplastic, it’s stretchy, tough, nontoxic, and biodegradable.”

All those attributes make it a great material for a future where renewable resources and avoidance of persistent plastic pollution are the norm, Zha said.

Polyethylene plastic, found in products such as plastic bags, water bottles, and food packaging, is the biggest contributor to plastic pollution globally and can take upward of 1,000 years to degrade naturally. Only a small portion of polyethylene plastic is recycled, so the bacteria used in the study could help “upcycle” some of the remaining waste.

Pseudomonas aeruginosa, the bacteria used in the study, can naturally consume polyethylene as a food source. The RPI team tackled the challenge of engineering this bacteria to convert the carbon atoms of polyethylene into a genetically encoded silk protein. Surprisingly, they found that their newly developed bacteria could make the silk protein at a yield rivaling some bacteria strains that are more conventionally used in biomanufacturing.

The underlying biological process behind this innovation is something people have employed for millennia.

“Essentially, the bacteria are fermenting the plastic. Fermentation is used to make and preserve all sorts of foods, like cheese, bread, and wine, and in biochemical industries it’s used to make antibiotics, amino acids, and organic acids,” said Mattheos Koffas, Ph.D., Dorothy and Fred Chau ʼ71 Career Development Constellation Professor in Biocatalysis and Metabolic Engineering, and the other researcher leading the project, and who, along with Zha, is a member of the Center for Biotechnology and Interdisciplinary Studies at Rensselaer.

To get bacteria to ferment polyethylene, the plastic is first “predigested,” Zha said. Just like humans need to cut and chew our food into smaller pieces before our bodies can use it, the bacteria has difficulty eating the long molecule chains, or polymers, that comprise polyethylene.

In the study, Zha and Koffas collaborated with researchers at Argonne National Laboratory, who depolymerized the plastic by heating it under pressure, producing a soft, waxy substance. Next, the team put a layer of the plastic-derived wax on the bottoms of flasks, which served as the nutrient source for the bacteria culture. This contrasts with typical fermentation, which uses sugars as the nutrient source.

“It’s as if, instead of feeding the bacteria cake, we’re feeding it the candles on the cake,” Zha said.

Then, as a warming plate gently swirled the flasks’ contents, the bacteria went to work. After 72 hours, the scientists strained out the bacteria from the liquid culture, purified the silk protein, and freeze dried it. At that stage, the protein, which resembled torn up cotton balls, could potentially be spun into thread or made into other useful forms.

“What’s really exciting about this process is that, unlike the way plastics are produced today, our process is low energy and doesn’t require the use of toxic chemicals,” Zha said. “The best chemists in the world could not convert polyethylene into spider silk, but these bacteria can. We’re really harnessing what nature has developed to do manufacturing for us.”

However, before upcycled spider silk products become a reality, the researchers will first need to find ways to make the silk protein more efficiently.

“This study establishes that we can use these bacteria to convert plastic to spider silk. Our future work will investigate whether tweaking the bacteria or other aspects of the process will allow us to scale up production,” Koffas said.

“Professors Zha and Koffas represent the new generation of chemical and biological engineers merging biological engineering with materials science to manufacture ecofriendly products. Their work is a novel approach to protecting the environment and reducing our reliance on nonrenewable resources,” said Shekhar Garde, Ph.D., dean of RPI’s School of Engineering.

The study, which was conducted by first author Alexander Connor, who earned his doctorate from RPI in 2023, and co-authors Jessica Lamb and Massimiliano Delferro with Argonne National Laboratory, is published in the journal “Microbial Cell Factories.”

Business leaders, product developers, and technology scouts convened at the RISE® (Research, Innovation & Science for Engineered Fabrics) Conference, Sept. 26-27, Raleigh, NC for two days of valuable insights in material science, process and sustainability innovations. RISE is co-organized by INDA and The Nonwovens Institute, North Carolina State University.

Industry, academic, and government experts shared their expertise in these key areas:

• The future of nonwoven manufacturing
• Real-world applications and advances in filter media
• rPolymers and sustainability
• Innovative strategies and circular solutions
• Advancements in sustainable nonwoven applications
• Market statistics and data trends

A highlight of RISE was a poster presentation of fundamental nonwovens research by The Nonwovens Institute’s graduate students. As an added value, The Nonwovens Institute offered RISE participants a tour of its world-class facilities located on the Centennial Campus of North Carolina State University, featuring the most extensive set of lab- and pilot-scale equipment found anywhere including all the nonwovens platform and testing technologies.

RISE® Innovation Award Winner
TiHive won the 2023 RISE Innovation Award for their SAPMonit technology. TiHive’s innovation, SAPMonit – a technology breakthrough, inspects millions of diapers weekly. SAPMonit delivers lightning-speed inline inspection of superabsorbents’ weight and distribution, optimizes resources, detects flaws, and accelerates R&D. SAPMonit utilizes advanced see-through cameras, high-speed vision algorithms, and secure cloud integration, revolutionizing industry norms. SAPMonit has great potential for sustainability, cost reduction, and enhanced customer satisfaction as it avoids hundreds of tons of plastic waste per year per machine.

The RISE Innovation Award finalists included Curt. G. Joa, Inc. for their ESC-8 – The JOA® Electronic Size Change, Fiberpartner Aps for their BicoBio Fiber, and Reifenhäuser REICOFIL GmbH & Co. KG for their Reifenhäuser Reicofil RF5 XHL.  Together, these finalists’ innovations have the potential to reduce plastic waste by millions of kgs.

DiaperRecycle won the 2022 RISE® Innovation Award for its innovative technology to recycle used diapers into absorbent and flushable cat litter. By diverting used diapers from households and institutions, and separating the plastic and fiber, DiaperRecycle strives to decrease the climate-changing emissions of diapers from landfills.

2023 INDA Lifetime Technical Achievement Award
Ed Thomas, President, Nonwoven Technology Associates, LLC, received the 2023 INDA Lifetime Technical Achievement Award for his decades of nonwoven contributions to the growth and success of the nonwoven industry.

RISE 2024 will be held October 1-2, 2024 at the James B. Hunt Jr. Library at North Carolina State University in Raleigh, NC.

Swansea University academics have pioneered a process which converts the carbon found in discarded facemasks to create high-quality single-walled carbon nanotubes (CNT) which were then used to make Ethernet cable with broadband quality.
 
The study, which has been published in Carbon Letters, outlines how this new green chemistry could be used to upcycle materials which would otherwise be thrown away and transform them into high value materials with real-world applications. The CNTs produced by this technique have the potential not only to be used in Ethernet cables, but also in the production of lightweight batteries used in electric cars and drones.

Professor Alvin Orbaek White, of Swansea University’s Energy Safety Research Institute (ESRI):
“Single-use facemasks are a real travesty for the recycling system as they create vast amounts of plastic waste - much of it ending up in our oceans. During the study, we established that the carbon inside the facemask can be used as a pretty good feedstock to make high-quality materials like CNTs.

“CNTs are highly sought-after because they have preferential physical properties and tend to be much more costly on an industrial scale. So, through this study, we demonstrated that we could make very high value materials by processing the CNTs from what are, essentially, worthless waste facemasks.”

The team also studied the energy costs involved in using this process and concluded that the technique was green not only in levels of resource consumption but also in the product value generation as opposed to waste creation. Also, the Ethernet cable produced using the CNTs was good quality and adhered to Category 5 transmission speeds while easily exceeding the benchmarks set for broadband internet in most countries, including the UK.

Professor Orbaek White said:
“Using CNT films in batteries instead of metal films has a lower impact on the environment as the use of carbon offsets the need for mining and extraction activities. This is a crucial piece of work as it contributes to not only a circular economy but is also scalable and is viable for industrial processing and has green chemistry at its core.”

When plastics enter the environment, this brings with it many negative effects: these range from suffocating living organisms to transfer within the food chain and physical effects on an ecosystem. In addition, there are dangers from the release of additives, monomers and critical intermediates of metabolic processes, the metabolites.

How great the long-term impact of plastic emissions actually is, is not yet clear at the present time. In order to create a political decision-making basis for dealing with plastic emissions, researchers from Fraunhofer UMSICHT and the Ruhr University Bochum have therefore developed a budget approach and an LCA impact assessment methodology in the "PlastikBudget" project from December 2017 to the end of August 2021. The researchers have now completed the project. The result: When driving a car, a person emits more than half of their individual plastic emission budget through tire wear.

How big is the long-term impact of plastic emissions?
Six percent of global petroleum consumption goes to the plastics industry - and the trend is rising. While the plastics industry is an important economic factor in many countries, more and more plastic waste ends up in soils and oceans. Mostly in the form of highly mobile, small to large plastic fragments, plastic emissions can no longer be recovered from the environment. At the same time, the long-term effects of plastic in the environment are hardly predictable.

Due to the global and cross-generational dimension of the problem, it is important that science, industry and consumers work together to find a solution. One goal of the joint project PlastikBudget is therefore to quantify today's plastic emissions and to derive a plastic emissions budget. On this basis, the researchers can formulate quantitative emission targets that can be used to legitimize political decisions. In particular, the path from empirically verified data and normative values to a concrete emissions budget forms the core objective of the project.

From research to per capita emissions budget
Starting with a basic research on plastic quantities in the environment, the project addresses two major topics: The development of a budget approach and the development of an impact assessment method that can be used in life cycle assessments to consider potential environmental impacts of plastic emissions. Participatory formats complete the project. In this way, the results are anchored in political and scientific discourse. In the course of the project, the researchers will answer the following questions: What quantities of plastic are currently being discharged and what quantities have already accumulated? What quantities of plastic in the environment are still acceptable? How long does it take for plastics to degrade in real environmental compartments? How are the risks posed by different plastic emissions adequately represented? Finally, from the answers, they calculate a value for current emissions and what they consider to be an acceptable emissions budget.

250 million tonnes of PPE for 7.8 billion people
To measure plastic pollution, the researchers in the PlastikBudget project have developed the persistence-weighted plastic emission equivalent (PPE for short). This represents a virtual mass that takes into account the period of time until a specific plastic emission is degraded, e.g. in soil, freshwater or seawater. Relevant properties for this are the location of the emission, the material type, the shape of the plastic emission as well as the size of the emitted plastic part and the final environmental compartment in which the plastic remains. In the case of plastics that degrade completely within one year, the plastic emission equivalent corresponds to the real mass. If the degradation time is longer, it increases accordingly.

"Based on the thesis that the total amount of plastics already accumulated in the environment today has just reached a critical quantity, we were able to calculate a global plastic emission budget of 250 million tonnes of PPE," explains Jürgen Bertling, project manager of the project and scientist at Fraunhofer UMSICHT. "If each of the 7.8 billion people is allocated the same emission rights, this results in an individual budget of 31.9 kilograms of PPE per person and year."

Driving consumes half of the individual plastic budget
However, tire wear from driving alone corresponds to a plastic emission equivalent of 16.5 kg PPE per year and thus consumes more than 50 per cent of an individual's budget. Even waste from ten coffee-to-go disposable cups would consume 13.5 kg of PPE per year, more than a third of one's budget. "This is because the plastics used in disposable cups are more difficult to degrade than the rubber in the tire," explains Jan Blömer from Fraunhofer UMSICHT, who played a key role in developing the calculation methodology. The consumption of a coil of polyamide for a lawn trimmer, which releases microplastics when used, also weighs in considerably at 5.1 kilograms of PPE. Microbeads in cosmetics or the one-time sanding of a front door, on the other hand, consume significantly less of the individual emissions budget with 1.1 kg PPE and 0.5 kg PPE, but are still quite relevant in the overall balance.

Many other everyday activities also lead to plastic emissions. Nevertheless, the researchers show that the calculated budget limits can be met in various scenarios. However, such a scenario also entails considerable effort and massive changes in the way we deal with plastics today. One possible scenario to meet the budget would be a reduction of emissions by more than 50 per cent, if at the same time at least 50 per cent of all emissions consisted of readily degradable plastics.

Further work on accounting for plastic emissions in life cycle assessments
The persistence-weighted plastic emission equivalent developed in the PlastikBudget project could also represent a new impact category in life cycle assessments in the future. "With the help of factors that reflect the persistence of plastics in the environment, it will be possible in future to compare different product alternatives in terms of their plastic emission footprints," says Dr Daniel Maga, who is coordinating the corresponding further development of the life cycle assessment methodology at Fraunhofer UMSICHT. A corresponding exchange with companies is taking place here. However, implementation in the life cycle assessment methodology and the associated software solutions requires broad acceptance in the scientific community and must be prepared in corresponding standardisation committees.

The project is part of the research priority "Plastics in the Environment" (PidU) of the Federal Ministry of Education and Research (BMBF), in which 18 collaborative projects with around 100 partners from science, industry, associations, municipalities and practice want to clarify fundamental questions about the production, use and disposal of plastics. The research focus "Plastics in the Environment - Sources, Shrinking, Solutions" is part of the Green Economy flagship initiative of the BMBF framework programme "Research for Sustainable Development" (FONA3).

Fraunhofer Institutes pave new ways in plastics recycling

A sustainable society, the renunciation of fossil raw materials, climate-neutral processes - also the chemical industry has committed itself to these goals. For the industry, this means a huge challenge within the next years and decades. This structural change can succeed if all activities - from the raw material base to material flows and process technology to the end of a product's life cycle - are geared towards the goal of sustainable value creation. The key to this is innovation.

Plastics such as polyethylene (PE), polypropylene (PP) or polystyrene (PS), which are currently produced almost entirely from fossil raw materials, are fundamental to many everyday products and modern technologies. The carbon contained in plastics is an important resource for the chemical industry. If it is possible to better identify such carbon-containing components in waste, to recycle them more effectively, and to use them again to produce high-quality raw materials for industry, the carbon can be kept in the cycle. This not only reduces the need for fossil resources, but also pollution with CO₂ emissions and plastic waste. At the same time, the security of supply for industry is improved because an additional source of carbon is tapped.

The "Waste4Future" lighthouse project therefore aims to create new opportunities for recycling plastics in order to make the carbon they contain available as a "green" resource for the chemical industry. "We are thus paving the way for a carbon circular economy in which valuable new base molecules are obtained from plastic waste and emissions are largely avoided: Today's waste becomes tomorrow's resource," says Dr.-Ing. Sylvia Schattauer, deputy director of the Fraunhofer Institute for Microstructure of Materials and Systems IMWS, which is heading the project. "With the know-how of the participating institutes, we want to show how the comprehensive recycling of waste containing plastics without loss of carbon is possible and ultimately economical through interlocking, networked processes." The outcome of the project, which will run until the end of 2023, is expected to be innovative recycling technologies for complex waste that can be used to obtain high-quality recyclates.

Specifically, the development of a holistic, entropy-based assessment model is planned (entropy = measure of the disorder of a system), which will reorganize the recycling chain from process-guided to material-guided. A new type of sorting identifies which materials and in particular which plastic fractions are contained in the waste. Based on this analysis, the total stream is separated and a targeted decision is then made for the resulting sub-streams as to which recycling route is the most technically, ecologically and economically sensible for this specific waste quantity. What cannot be further utilized by means of mechanical recycling is available for chemical recycling, always with the aim of preserving the maximum possible amount of carbon compounds. Burning waste containing plastics at the end of the chain is thus eliminated.

The challenges for research and development are considerable. These include the complex evaluation of both input materials and recyclates according to ecological, economic and technical criteria. Mechanical recycling must be optimized, and processes and technologies must be established for the key points in the material utilization of plastic fractions. In addition, suitable sensor technology must be developed that can reliably identify materials in the sorting system. Machine learning methods will also be used, and the aim is to link them to a digital twin that represents the properties of the processed materials.

Another goal of the project is the automated optimization of the formulation development of recyclates from different material streams. Last but not least, an economic evaluation of the new recycling process chain will be carried out, for example with regard to the effects of rising prices for CO₂ certificates or new regulatory requirements. The project consortium will also conduct comprehensive life cycle analysis (LCA) studies for the individual recycling technologies to identify potential environmental risks and opportunities.

For the development of the corresponding solutions, the participating institutes are in close exchange with companies from the chemical industry and plastics processing, waste management, recycling plant construction and recycling plant operation, in order to consider the needs of industry in a targeted manner and thus increase the chances of rapid application of the results achieved.

The following Institutes are involved in the Fraunhofer lighthouse project "Waste4Future":

• Fraunhofer Institute for Microstructure of Materials and Systems IMWS (lead)
• Fraunhofer Institute for Non-Destructive Testing IZFP
• Fraunhofer Institute for Materials Recycling and Resource Strategy IWKS
• Fraunhofer Institute of Optronics, System Technologies and Image Exploitation IOSB
• Fraunhofer Institute for High Frequency Physics and Radar Techniques FHR
• Fraunhofer Institute for Structural Durability and System Reliability LBF
• Fraunhofer Institute for Process Engineering and Packaging IVV

In the "AgriTex" innovation project, WESOM Textil GmbH, together with the Fiber Institute Bremen e.V. and the Institute for Polymer and Production Technologies e.V., has set itself the goal of developing a compostable technical textile that is to be used in agriculture, among other things. The project is funded over three years by the Central Innovation Program for SMEs (ZIM) and has a funding volume of around 570,000 Euros. A corresponding application was approved by the Federal Ministry for Economic Affairs and Energy (BMWi) in April 2020.

Plastics have become an integral part of our everyday lives and are used in a wide variety of areas. At the same time, pollution from plastic waste is one of the greatest global problems of our time. There are already various options for the sensible and environmentally friendly disposal of plastics, e.g. recycling or thermal recovery. However, it cannot always be guaranteed that the waste is also disposed of in the corresponding disposal routes. For example, in agriculture, even if used properly, a release cannot always be prevented or a return is not possible depending on the application. Biodegradable plastics can help to solve this problem, but many of today's products only rot very slowly, as otherwise the required stability and robustness cannot be guaranteed.
     
The aim of the "AgriTex" project partners is to develop an innovative, biodegradable textile for applications in agriculture. On the one hand, the textile withstands the highest mechanical and weather-related requirements during use, on the other hand it rots quickly after a predefined period of use under natural conditions in the environment or on the compost. This two-phase behavior is made possible by a new type of bicomponent fiber made from the biodegradable plastic PLA. The new technology is to be developed and tested using a hail protection net for fruit growing. Hail protection nets are exposed to considerable loads from various weather conditions and usually have to be replaced after a few seasons. Proper disposal of the old nets represents a considerable cost factor for agricultural businesses. With "AgriTex" the nets can be composted with other biological waste in a cost-neutral manner. In addition, unintentionally released netting components from the structure remain, e.g. by storms or damage caused by game, no longer in the long term in the environment and the pollution of ecosystems by plastic waste is effectively prevented. The ecological and economic advantages of the new technology are not only in demand in fruit growing, but will also be of interest for many other applications in agriculture, landscaping or fishing in the future.
 
The idea for the “AgriTex” project came about as part of the PREVON - Production Evolution Network innovation network, which is funded by the Central Innovation Program for SMEs (ZIM). As part of the membership, the partners are actively supported in the implementation of R&D projects and in securing funding.