The treatment of wool waste using anaerobic digestion

Project Details

Description

There is growing interest in using wool as an eco-friendly alternative to plastic, particularly in agriculture. It is anticipated that end of life wool waste will increase. However, the properties that give wool its’ durability and stability also make it difficult to treat. This can be attributed to a strong external cuticle, strengthened by internal disulphide bonds. A traditional approach to treat wool waste is via incineration, which incurs high operational costs and contributes to the production of noxious gases. Wool may be composted but release gases such as methane and carbon dioxide directly into the atmosphere. This form or treatment may also be restricted by current regulations.

Wool is a rich source of carbon and - in theory - would be an excellent candidate for anaerobic digestion (AD). It is a natural process involving a consortium of bacteria to facilitate the biodegradation of organic material. The output of methane, known as biogas, can be utilised as a renewable energy source by conversion to combined heat and power or injected into the gas grid. Digestate can be utilised as a bio-available source for plant growth. This would be a major contribution to creating a highly sustainable process and maximising the extraction of valuable resources from a waste product.

Research investigating the AD of wool waste is scarce. This is likely due to the stability and durability of the raw material. As a result, wool is too stable for biodegradation in its current state and requires pre-treatment to encourage hydrolysis. Also, AD was typically associated with sewage sludge and slurry waste. It has only recently gained attention in other industries such as distillery effluent, wastewater and co-digestion of wastes. Research available is focuses on pre-treating wool using either chemical, physical or enzymatic hydrolysis. Various approaches have been used to facilitate the hydrolysis of wool for the extraction of reusable components such as keratin. This includes reducing agents and ionic liquids and may be applicable to this research project.

There appears to be a gap in knowledge with respect to wool waste and anaerobic digestion. However, there are advances in terms of pre-treatments that may help to improve AD suitability. There is also the potential to co-digest wastes and promote a circular treatment system. This has not been discussed in detail but may be something to consider as an opportunity to maximise nutrient and energy recovery.
Short titleAnaerobic digestion of wool waste
AcronymADWW
StatusActive
Effective start/end date1/10/231/10/24

UN Sustainable Development Goals

In 2015, UN member states agreed to 17 global Sustainable Development Goals (SDGs) to end poverty, protect the planet and ensure prosperity for all. This project contributes towards the following SDG(s):

  • SDG 7 - Affordable and Clean Energy
  • SDG 12 - Responsible Consumption and Production

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