A number of technologies emerging that are poised to eliminate waste in industries from fast fashion to biofuels. These procedures combine mechanical and chemical processes to break down waste products into their constituent parts that can either be recycled or made into entirely new products.
For example, Bloom Biorenewables was spun out of the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland in 2019 and has developed the aldehyde-assisted fractionation (AAF) technology that selectively isolates cellulose, hemicellulose and lignin – three of the most abundant biopolymers – from plants and converts them into added-value chemical products. In this process, lignocellulosic biomass like wood and wood-like materials, such as hazelnut shells, are converted into cellulose, lignin and hemicellulose-derived sugars to produce a variety of products including fine and bulk bio-chemicals, bio-polyester and composites, fibres and fuels and fuel additives.
“Cellulose is typically the only fraction of biomass that is used today, while lignin and hemicellulose are discarded because people don't know how to extract it without degrading it,” explains Florent Héroguel, its COO and co-founder. “To describe it in a non-scientific way, an egg is also composed of three components: the shell, the yolk and the white. You can crush it in your hand and you will get a mixture of the three components which not convenient, but you can still make scrambled eggs. Basically, this is what the industry is doing today with biomass. Instead of doing this at Bloom, we found a way to carefully crack the egg and separate the yolk the white and the shell. Then you can develop recipes from each ingredient because they are separated. This is, basically, what we do with biomass.”
Much like at a distillery, 40kg of biomass is placed into a 250-litre batch reactor where patented chemicals and bio-based solvents are added and heated to 80°C for three hours. After this the cellulose (the only solid by-product of this process) is filtered out, then a second filtration is done which separates the lignin and the hemicellulose. Some 35kg of usable product is produced, and the 5kg left over is burned to heat the next vat.
The part of the process that sets Bloom Biorenewables apart is being able to separate the lignin and the hemicellulose, which is not typically done by other companies and opens up new areas in which to sell their products. This includes offering much purer, quality biofuels, it says.
One of the key areas for all these companies is reducing waste to zero. Bloom Biorenewables uses organic solvents in its process which works in a closed loop. Héroguel says: “We have key technologies to manage the recovery of these organic solvents. There is also water in the system so isotopic mixtures tend to form. This is a great set of challenges to manage without using too much energy with high efficiency and high purity.”
Bloom will work with one of its main investors, Yokogawa Electric, to automate the process to have as little human intervention as possible. This is also to improve the efficiency, economy and the ecological aspects of its process.
Héroguel adds: “We’re still in the development phase, we’re a young company and we’re covering most of the supply chain ourselves. We’re focussing on our core activity, the bio-refining. The goal in the midterm is to become a technology provider and to licence these technologies to others, but right now we need to validate the technology.”
CELLULOSE AND FABRIC
Before an article of clothing makes it to a shop it has been through more steps than most people realise. Often one producer makes the yarn, another knits or weaves it into textile fabric, and a third makes the shirt from the fabric. Clothes that are no longer wanted or not sold end up in landfills. Hardly any are recycled because cotton and viscose can’t be recycled with suitable quality.
However, Swedish company Renewcell has devised a process to recycle cotton and other cellulose fibres to transform them into a new, biodegradable, virgin quality raw material it calls ‘Circulose’ pulp which can be used to make new clothes. This process starts out with a bale of clothing being shredded to separate metallic items like buttons and zippers and to reduce the size of the textile fibres for the next, wet stage of the process. Here, chemicals and pumps are used to ‘adjust the properties of the cellulose in the material’.
Renewcell’s chief marketing officer & head of investor relations, Harald Cavalli-Björkman adds: “I have to be a bit less transparent about exactly what goes on, but we want to get it to the right viscosity, reactivity and brightness. Our patents are process patents, covering the sequence in which we subject the materials to the various systems, the acid and alkaline conditions, the differing temperatures, physical treatments and things like that. Then we bleach the materials, just like you would conventionally, to get it white which is what we need to get it to virgin equivalent.”
The last step in the wet stage of the process is where fibre contaminants, such as polyester, are separated out. Finally, the cellulose pulp is put on a conveyor belt and subjected to heat and pressure to turn it into 80x60cm sheets in a process similar to papermaking. Then the sheets are baled up and sold to manufacturers that create fibres from it, which is then used to make yarns, fabric and eventually new clothes.
Renewcell is in the process of moving into a new facility, an ex-paper mill in Sweden, which will allow it to increase production capacity from 4,500 tonnes per year to 60,000 starting in the first half of 2022. Because the process is similar to paper pulp making, it plans to re-employ up to 100 people that were made redundant when the papermaker closed its doors last year.
“800 people were let go at that plant, which is sad of course,” says Cavalli-Björkman. “The good part for us is that a lot of highly competent process engineers and operators are now available to start working with us on recycling materials in a process that is on the whole, fairly similar to what they’ve been doing. That lowers risk and increases our speed at getting up to commissioning.” Cavalli-Björkman says that by doing this, Renewcell is causing an industrial evolution by using existing machinery and skills and augmenting them to carry out a new process making new materials.
Renewcell has already received a contract from a Chinese viscose fibre producer for 40,000 tonnes, two thirds of their future capacity, and are in discussions with other European, Indian and American companies.
The drying technology used in Renewcell’s process is provided by pulp, paper and energy process technologies supplier Valmet. Valmet is also supplying Finland’s first commercial scale fibre production facility run by Spinnova and Suzano. The joint-venture’s SPINNOVA fibre is said to be a sustainable natural textile fibre produced from cellulose or waste streams, such as wood, textile or food waste, without involving any harmful chemicals, with minimal water use and emissions, and zero waste.
Jari Vähäpesola, Valmet’s paper business line president, says: “We want to support our customer’s journeys in converting renewable resources into sustainable results. This delivery is an excellent example of our strong focus on creating new technological innovations, and how we can create new opportunities in the fibre-based industry. We can use our existing technologies, and our know-how is essential when scaling up the production.”