Clean diaper recycling
With an enzymatic recycling process from diaper waste, important basic components for the chemical industry, bioethanol or new polymers can be obtained.
Researchers at the Austrian Centre of Industrial Biotechnology (acib) have developed an environmentally friendly recycling process for commercial diapers. Up to now, diapers have been incinerated or landfilled, as recycling the composites was considered too expensive and of insufficient quality for the industry in terms of a circular economy. Valuable, reusable resources were thus lost. The enzymatic recycling process of acib could close this circle. Important basic components for the chemical industry, bioethanol or new polymers could be extracted from the diaper waste. The project was recently nominated for the riz up Genius Ideas and Founder Award 2020.
Worldwide, more than one ton of diaper waste is produced per minute. In the EU alone, more than 20 billion disposable diapers are produced annually. These consist of a complex mixture of polyethylene, polypropylene, cellulose and superabsorbent plastic fibers. The latter are mainly made of granular sodium polyacrylate, a chemical composite that can absorb or absorb hundreds of times the mass of a diaper. All these materials are considered valuable, reusable resources, which are usually incinerated or landfilled at the end of their life cycle and are therefore irretrievably lost. The reason: Separation and thus clean recycling is complex and expensive and therefore not yet possible or only of insufficient quality for the industry in terms of a circular economy. "In order to use the more than 3.5 million tons of diaper waste per year as an important source of raw materials for the first time, a working group of the Austrian Centre of Industrial Biotechnology (acib) at the Tulln site has started thinking about the development of a completely new biotechnological approach to diaper recycling.
Enzymes as environmentally friendly helpers
At the heart of the technology - after an initial cleaning step of the diapers - is the use of enzymes. "Enzymes are biological catalysts made of bacteria and fungi that control and initiate numerous biological and chemical processes. The enzymes we use, which include cellulases, are able to separate and recycle the diaper fibers, whereupon cellulose fibers can be broken down into the basic substance glucose and consequently used as a nutrient source by fermentation," explains acib scientist Sara Vecchiato, who also conducts research at the Institute of Environmental Biotechnology at BOKU Vienna. The enzymatic degradation products of the plastic fibers are valuable basic components for chemical processes or the production of bioethanol and new polymers. The advantage of the technology is that they can be recovered easily and in pure form. In addition, crude oil, which is still used as a basic building block for the polymers processed in diapers, can be saved and thus the environment is protected. "Unlike the thermal recycling of diaper waste, the acib process also produces no CO2. During the entire process we also do not need any hazardous chemicals. The recycling process takes place at room temperature, does not require any complex and expensive infrastructure and is therefore an environmentally friendly measure to slow down the effects of climate change," Vecchiato emphasizes.
Planned use in industry
"Very promising results on the new process on a laboratory scale are currently available. In order to finally establish a process suitable for industrial use, the enzymatic process is currently being further developed and improved", explains Matthias Slatner, Open Innovation Manager at acib in Tulln. The focus is currently on the development and optimization of suitable enzymes with a view to commercial application. "We assume that about three years of further research and development activities in the laboratory will be necessary until we are ready", reveals Vecchiato, who hopes that besides a process optimization, a patenting of the know-how will be implemented in the future. On the one hand, the researchers' goal is to win a partner from industry for the implementation of the process. On the other hand, they also want to (further) develop non-oil-based materials for diaper production in order to make this industrial sector "cleaner" in terms of the bio-economy. The acib project was recently nominated for the riz up Genius Award 2020, which honors creative companies, business ideas and projects in Lower Austria. Slatner: "The nomination confirms the enormous potential of our biological diaper recycling approach to open up new business areas, saving precious resources and harmful CO2 and, last but not least, doing something good for the environment and the climate".