Did you know babies need up to 3 000 nappies during their first year? I probably wouldn’t have believed this statistic until recently. So much work, so much waste. Indeed, my five-month-old son Robin provides my husband and I with regular smelly surprises. We’ve been caught in the crosshairs quite a few times – though I can laugh about it now!
‘You know, you should write about recycling diapers,’ I’ve heard many colleagues joke the last couple of weeks. ‘You’re an expert, after all,’ was one observation, followed by hearty laughter. I rolled my eyes and finished the article I was working on. I later thought ‘What the hell – why not? Maybe that will be the end of it’.
Let’s jump in. Recycling diapers has long been regarded as a niche not many in the industry want to explore. Pilot projects pop up every now and then, without much follow-through, mainly because of contamination concerns and material complexity. Also, it’s not a very appealing waste stream. E-scrap is hot. So is ocean plastic. Nappies are a blip on the radar.
Super absorbing, super tricky
Let’s look at the material composition first. The core of a nappy is made of special polymers called superabsorbents. These tricky crosslinked polymers pose a recycling challenge. Luckily, bright minds at Karlsruhe Institute of Technology (KIT) are currently conducting experiments to dissolve these polymers using water and UV radiation. The German researchers report they can do so energy efficiently and without relying on chemicals.
The KIT team explains that UV radiation helps break down the chemical chains that hold the polymers together ‘200 times faster than before’, using acid. An added benefit is that the method works at room temperature. After 16 hours, the dissolved polymers can be processed into new adhesives and dyes.
There are many products containing superabsorbents, such as bandages and napkins. This means a solution for diapers could be extended to a much bigger waste stream.
Paving new roads
Another recent breakthrough involves using recycled diapers in road construction. Welsh company NappiCycle converted 100 000 diapers into plastic pellets to create a new type of asphalt last year. The Welsh government provided EUR 155 000 in funding to resurface a 2.5 kilometre stretch of the busy A487 highway.
To date, NappiCycle has processed nappies into a variety of products, also including road signs and construction panels. The company handles around 40 million discarded diapers every year. The recycled pellets are unrecognisable; the output is a clean, evenly shaped and odourless material.
I admire the practical stance of company director Director Rob Poyer. He argues we need to ‘broaden our minds’ and that we’re too quick to label unpopular materials as ‘waste’.
Homes of the future
Further innovative uses of recycled diapers could provide affordable living options. Researchers at the University of Kitakyushu in Japan are leading an R&D project transforming nappies into concrete and mortar. Environmental engineer Siswanti Zuraida from Indonesia came up with the idea, inspired by the fast-growing population of her home country.
She estimates that recycling nappies into one-storey eco-homes could replace almost 30% of traditional materials. For three-storey homes, this could be 10%. For separate structures like walls, it could be up to 40%. Even adding 1% recycled diapers to concrete greatly enhances internal curating hydration and yields more robust, durable materials.
Bear in mind the scale of the problem. Almost two million tonnes of used diapers are incinerated across Germany every year. In the US, the figure is closing in on five million tonnes per year. Globally, every minute, more than 300 000 disposable nappies are sent to landfill, incinerated or end up in the environment, according to UNEP data.
As a new parent it’s hard to imagine total sales topping US$ 61 billion (EUR 56 billion) in 2022. With the world’s booming population this is set to reach 105 billion by 2032.
It’s good to know that there can potentially be happy ending to this mundane and overlooked waste problem.