Compostability of wool textiles by soil burial

Abstract

Chemical processing has the potential to impact the composting of wool fabrics, influencing potential end of life options. The aim of this study was to investigate the comparative composting behaviors of a range of knitted and woven merino apparel fabrics. The range included scoured only control fabrics and variants which had undergone different chemical processes during manufacturing, including dyeing, bleaching, stain-repellence and various shrink-resist treatments. Biodegradation by composting was elicited by a soil-burial process incorporating three sets of randomized samples buried to a depth of 10 cm. Replicates were removed at regular intervals up to a maximum of 15 weeks burial. The dyes present in the fabric showed the greatest impact on composting. Chrome dyed samples exhibited only 60% mass loss over the trial period, whereas the other 10 fabrics all lost on average over 95%. When assessing easy care treatments, chlorine–Hercosett provided consistent initial resistance to decomposition. Soil burial test results suggested that chemical processing does impact the composting of wool fabrics, under the conditions of soil burial. Statistically significant longer-term effects were only observed for the chrome dyed sample. • Chemical processing of wool fabrics influences the onset of composting as a result of soil burial. • Dyeing fabrics had the greatest impact on the onset of composting as a result of soil burial. • Machine-washable wool has initial resistance to decomposition, compared with untreated wool, as a result of soil burial.