UK-based company Knowaste claims that they are "world's first provider of a recycling solution for nappies, adult incontinence and feminine hygiene (AHP) products" Who would have ever thought of turning used sanitary products into roofing material? AHPs take 500 years to decompose when landfilled and a waste of recoverable material when incinerated. Knowaste has also found that the use of disposable nappies has increased over the past 20 years. Each baby will use about 6000 diapers before it is potty trained. In the UK alone, 3 billion are used each year, contributing about half a million tonnes of waste. Because people are living longer, the use of adult incontinence diapers is also on a rise and 50% of nursing home residents in the UK suffer from incontinence. In the UK alone, 18 million women use sanitary protection which generates over 200,000 tonnes of waste per year. The UK is of course a relatively small country, which makes the statistics mind-boggling when you consider the implications for larger countries. The potential for scale-up of their business model is huge. Knowaste has pioneered a process that turns AHP waste into plastic pellets which can then be transformed into various materials like roof tiles and plastic tubing. Over the next five years, the company plans on opening five absorbent hygiene recycling plants in the UK. This will significantly reduce the 1.1 billion pounds of diaper waste that currently get sent to landfills each year.

The recycling process starts off with sterilization in an autoclave. Then the AHP material is mechanically separated into the individual components: organic residue, plastic and super absorbent polymers (SAP). A chemical treatment then deactivates the SAP and any plastic material is sent to a separate device for processing. The plastic is filtered, cleaned and compressed into small pellets that can be sold for reuse. The SAP then goes through another screening process and any water used is recaptured, internally treated and reused within the system. The organic waste that left is dried and used to create green energy. Each recycling facility is capable of processing 80,000 pounds of absorbent hygiene products every year. Below is a diagram of what a nappy contains and a little bit of how their process works.

Knowaste is currently working with childcare centers and retirement homes to procure their supply of AHP waste but the possibility of working with city authorities to procure diaper waste from households is tremendous. Their new site in West Bromwich is a £5 million investment and will have the capacity to handle a fifth of the AHP waste stream which equates to saving 11,000 tonnes of GHG emissions a year. Pretty awesome for dirty nappies.

Source: https://www.triplepundit.com/story/2011/uk-company-turns-used-diapers-roofing-material/73711