Biodegradable nappies and sanitary pads could reduce the burden that fossil-based plastic litter puts on nature. The prototypes currently developed are meant to be of higher quality, but still, they are more expensive than the similar conventional products on the market. The BBI JU POLYBIOSKIN and EMBRACED projects are working on making nappies more sustainable.
Humans contribute to the planet’s pollution from the very early stage of their lives. EU statistics report that some seven million babies in Europe use up to 36 million disposable nappies in only one day. Scientists are sketching out different solutions to reduce the pollution from plastics. Although deployed on a small scale, these trials have encouraging results.
A consulting company specialised in R&D of disposable hygiene products, in Spoltore, near Pescara in Italy, is making a pioneering attempt to replace more than 90% of the content of the top and back sheets and absorbent cores of nappies with bio-based alternatives.
The main raw material used to develop the top layer and the back sheet is a synthetic plastic (PLA) produced from cornstarch, sugar beet and sugar cane. A cellulose derivative from wood serves as the basic matter for the core absorbent, chosen for its good imbibing capacity.
'The top layer has been tested in the lab, on human cellular cultures and it has been proved that this kind of plastic is more compatible with the skin, compared to the current fossil based polymers,' states Alessandro Gagliardini, researcher working for the company, Atertek.
In addition, the skin-contact materials are impregnated with biomolecules, providing anti-inflammatory properties to the final product, to prevent nappy rashes, according to Götz Ahrens, project manager at European Bioplastics, an association representing the interests of the bio-plastics industry and partner of the above-mentioned research within the BBI JU-funded POLYBIOSKIN project.
With regard to the safety of bio-based diapers, Professor Ioan Calinescu, from the Department of Bio-resources and Materials’ Science, University Politehnica of Bucharest, has a similar opinion: 'In order to avoid skin irritation, some antioxidant and antibacterial compounds can be added. Thus the biodegradable polymer does not harm the skin.'
On the other side, he highlights some properties that the traditional fossil-based diaper has developed over time: 'As far as I know, there is no existing bio-based polymer that is degradable and has the same properties, e.g. absorbency, weight, roughness, shape, as the one made from fossil materials. It is difficult to get all these properties.'
Alessandro Gagliardini admits that it is a complex matter, as the fossil-based diaper has achieved good qualities, like high absorbency or liquid retention capacity under pressure, in 30-40 years of development: 'We need to make some adjustments, probably a better rewet [the amount of liquid that returns to the surface of diapers when subjected to pressure – editor’s note] or more or less emphasis on fast acquisition of fluids, because it is really a new material,' he says, 'but the bio-based super absorber that we produce has very good capacity which would be sufficient for commercial application.'
The main parts of the nappy are now in the pilot phase and they are expected to enter the market in a year's time, at the earliest. Nevertheless, the new diapers will be more expensive than fossil-based products. 'Cost is expected to come down, as well, once the production and sales grow,' asserts Gagliardini.
The main advantage of the biodegradable components of the baby nappies lies in their ability to be destroyed. However, it does not mean that they should be thrown directly into the environment, as specific conditions are needed, under which the microbial activity can degrade.
'Looking at the most common end-of-life scenario for the absorbent hygiene products in Europe - incineration - it is clear that products from renewable carbon sources close the carbon loop, as opposed to fossil-based materials which at the end of life release additional CO2 into the atmosphere,' explains Götz Ahrens.
The long-term solution, according to scientists is to produce biodegradable plastic materials. A biodegradable product also opens the door to organic recycling, which means industrial composting - producing compost, a soil improver - and anaerobic digestion - turning biodegradable waste into biogas. From the cellulose-based material, another component in the structure of the nappy, one can produce cardboard or can use it in agriculture to improve water retention of arid soils.
FaterSMART, a company located in Pescara, Italy, took a step forward to innovative recycling of absorbent hygiene products (AHP). They developed a solution, able to recover the waste stream and turn it into plastic, cellulose and super absorbent polymer. 'Nappies and other used absorbent hygiene products that arrive at the plant after the collection phase are directly transferred to the autoclave, where, through steam pressure and without combustion, they are opened and sterilised,' explains Research and Development Director Marcello Somma.
According to him, this technology is able to recycle 100% of AHPs: 'From 1 tonne of used absorbent hygiene products we recover 150 kg of cellulose, 75 kg of plastic and 75 kg of super absorbent polymer. The remaining 700 kg is liquid waste.' He also says that their technology can preserve the high quality of the initial raw materials as it is transferred to the materials resulted from the recycling process.
The company also leads the BBI JU project EMBRACED, which is aimed at establishing an integrated bio-refinery in Amsterdam to recover the cellulosic fraction of post-consumer AHP waste and produce bio-based building blocks, polymers and fertilisers.
There is a significant waste stream of nappies coming from hospitals, care homes, households, nurseries, kindergartens and therefore recycling remains the best solution for them in the short and medium term. However, the condition for their re-use is the right collection, sorting and separation, meaning efficient waste management technologies and infrastructure have to be in place.
By Sorina Buzatu