Sweden: Circular Economy Textile Bioreactor Converts Waste into Biogas and Bioethanol
A multi-year collaboration between researchers within Resource Recovery at the University of Borås and a textile manufacturing company has resulted in a new type of reactor made of a textile material. The reactor transforms different kinds of waste into new products, such as biofuel.
Borås/Sweden — Research on waste recycling, such as wood residuals, agricultural or household waste, by converting it to bioethanol and biogas, has been going on for a long time at the university. However, they had used fixed reactors made of stainless steel or glass. On a larger scale, for example purification plants, the bioreactors were made of concrete.
A chance meeting between Mohammad Taherzadeh, Professor of Biotechnology at the University of Borås, and Fredrik Johansson, business developer and partner in F.O.V., who specializes in technical textiles, sparked the idea of a textile reactor.
The meeting led to a research collaboration in which the research team in the field of resource recovery would develop the technology to convert waste to biogas and bioethanol by anaerobic digestion or fermentation while continuing to develop processes for various applications. The company would contribute the textile material and the design of the reactor itself.
The research team specified the requirements for the reactor. In addition to low weight, it must still have the proper properties, such as being impermeable and able to withstand different substances, such as the chemicals and microorganisms that will work in the reactor. Externally, it must handle different kinds of weather and climates, and it must have a long life span.
A first prototype of the reactor saw the light of the day in 2014. It was a triangular and pyramidal creation, for stability. Over a few years, it was tested in several research projects. First, attempts were made to produce biogas with kitchen waste in the lab environment, then later with manure.
Since the prototype stage at the University of Borås and the development of different models and sizes at the partner company FOV Fabrics AB, the reactor has been introduced in several countries worldwide, mainly for the production of biogas.
Prior to stage 2 — to test the reactor in an outdoor environment--a different design was chosen. It was shaped as a lying bag, more suitable for a larger scale reactor.
The researchers fed the reactor with different types of waste and tried different mixtures to get as good a production of biogas as possible. They also tested reactors of different sizes to produce the desired technical characteristics. Today, textile reactors have been developed and established in several locations around the world to produce biogas on both small and large scales, ranging from a few cubic meters to 300 m3 large reactors. They are used so far mainly in agriculture.
Exploring Further Potential
But it doesn't stop there. Research on the textile reactor has entered stage 3 — to find new applications for it. In new projects, it is now being tested for the production of things other than biogas and bioethanol.
According to Mohammad Taherzadeh, a reactor is basically like any other vessel. What it produces depended on what you put in it and what microorganism was used in it. Right now he is trying to grow fungi in the reactor, Ascomycete, a kind of fungus that is also used as a foodstuff in Asia. The team is investigating whether they can grow it in the reactor to use in new products, such as for the production of animal feed.
The textile reactor is then filled with vinasse, a residual from sugar and ethanol production. The fungus grows in the reactor and will then be used for the production of animal feed. At the University of Borås, experiments are being carried out in lab environments, and in India pilot trials are being conducted; the results look promising.
The textile reactor can be fed with different types of material depending on what is to be produced. In ethanol production, sugar is added. Then the scientists use yeast for a fermentation process. And for biogas production they supply different kinds of waste. Then they use microorganisms that handle acid-poor conditions in the digestion process.
Technically, the textile reactor can be of great importance to the processing industry. The installation time is short, textile reactors can be used in any kind of space, both small and large, and they are perfect if you want to test new applications. They provide a great deal of flexibility, Taherzadeh claims.