OUR TECHNOLOGY
08
HOTROT DIAPER SYSTEM
Yes you can compost nappies!
While diapers and absorbent hygiene waste (AHW) contain plastic and other non-compostable materials a large portion is organic. The super absorbent polymer (SAP) which makes up more than 30% of a fresh nappy was initially developed by the US Department of Agriculture as an additive to improve the moisture holding capacity of soils and is commonly used in commercial composts such as potting and tub mixes.
For diaper and AHP composting HotRot offers an economic scalable commercial solution.
THE HOTROT BUSINESS CASE
GCS has worked with clients to design Diaper Composting Solutions utilising either our 1206 or 1811 HotRot Composting units. These plants incorporate pre (shredding) and post (screening) options to provide a complete turnkey business system which can be scaled to best meet our clients requirements.
Complete Solution
Source separation of diapers and AHW is fundamental and is not difficult to achieve. Many commercial premises (rest homes, aged and child care facilities, and hospitals, etc.) already practice source separation of this waste and indeed most parents also have some form of separation in the home, at least until it gets to the kerbside.
Commercial nappy composting plants have been established by Global Composting Solutions in New Zealand and a commercial AHW plant has been established in the UK.
Technical Benefits
Other technologies look to deconstruct diapers (nappies) and AHW and then extract value out of the recovered materials. These plants generally require sophisticated high capacity equipment with a high capital cost.
They rely on large “catchment” areas to provide waste with associated higher transportation costs.
Local Collection and Accessible Technology
The HotRot process focusses on the use of relatively standard technology to process used diapers and AHW into a useable compost and a waste plastic product that can be used as a fuel or in some form of recycling.
Once waste is received at site it is shredded using specialised shredders and mixed with commercial green waste (leaf and yard waste) prior to introducing to the HotRot composting units.
Most commercial diaper plants will use HotRot 1811 composting units but some smaller plants can utilise the HotRot 1206. After composting the material is screened and compost and plastic separated.
Pathogen Free Compost with Moisture Retention Properties
The compost produced by the HotRot is pathogen free and benefits from the presence of the super absorbent polymer used in diapers - the same product that is sold in nurseries and garden shops and is present in many commercial potting/tub mixes.
The nature of compost makes it ideal for production of “ready lawn” (turf) or the establishment of ornamental gardens or verge cover around motorways and roads.
TECHNICAL FEATURES AND BENEFITS
ENVIRONMENTAL BENEFITS
Environmental Benefits
A 2008 UK Environmental Agency lifecycle assessment study for disposable and reusable nappies concluded:
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That GHG emissions associated with an infant using disposable nappies (diapers) over two and a half years was 550kg CO2-equivalents.
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The GHG emissions associated with an infant using reusable cloth nappies (diapers), over two and half years, was 570kg CO2-equivalents.
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Manufacturing efficiencies and lighter disposables had reduced GHG emissions for disposables by 13.5% compared to a previous study but the manufacturing impacts were still greater than GHG emissions associated with landfill disposal.
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GHG emissions from reusable nappy use could be reduced by 40% by reusing nappies for a second child and line drying,
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Tumble drying of reusable nappies would increase the baseline figure of 570kg CO2-equivalents by 43%, and washing nappies at 90oC (194oF) instead of 60oC (140oF) would increase the figure by 31%; combining these two energy intensive scenarios would increase GHG emissions for the use of reusable nappies to 990kg CO2-equivalents.
Despite the convenience, and indeed limited GHG difference from reusable nappies, many parents feel guilty about the use of disposal nappies. Additionally with increasing uptake of diversion of other elements of the waste stream (organics and recyclables, etc.) disposable nappies make an increasing proportion of the residual waste stream.
Disposable nappies make up, on average 2-3% of mixed municipal waste stream, organics can make up 30-40% and recyclable materials 10-15%. Once recyclable materials and organics are removed, disposable nappies can be 5-8% of the residual.
Composting disposable nappies can reduce GHG emissions and produce a useable composted product and recover plastic for recycling or use as a fuel for energy generation.
Composting disposable nappies with other organics in a traditional composting system is not recommended as it adds costs to waste preparation and compost screening and clean-up. Plastic contamination in compost from "clean" source separated food and garden waste is a major problem for the composting industry.
Dealing with nappies (diapers) in a specialised HotRot composting facility enables processing conditions and equipment to be optimised. The small footprint and OdourFree guarantee of a HotRot composting facility ensures facilities can be located close to urban areas thus reducing transportation costs.