Abstract:
Bovine hair, resulting from the unhairing of hides and skins, forms a major component of tannery solid wastes that is often disposed to landfill. However, following increasing environmental legislation restricting the disposal of commercial and industrial organic wastes to landfill, alternative treatment of tannery solid hair waste is necessary. The overall aim of this research was to develop conditions favourable for the decomposition of bovine hair waste in a composting environment. In this study, chemical pretreatments of bovine hair were carried out to enhance susceptibility to enzymatic digestion. Pretreatment using a combination of potassium thioglycolate and sodium hydroxide enhanced enzymatic digestibility of hair. Comparative solubilisation of black, brown and white hair samples with sodium sulfide showed that, the percentage soluble nitrogen, from white hair was 73% (w/w) as compared to 28% (w/w) and 24% (w/w) of black and brown hair, respectively; indicating that white hair was more vulnerable to solubilisation. Although chemical pretreatment was effective, it was considered non-compatible with the composting process. Consequently, enzymatic and microbial degradation were considered suitable alternatives. The results of the preliminary biochemical studies indicated that, the breakdown of the hair structure was enhanced when treated with a combined protease solution containing proteinase K and trypsin enzymes as compared with individual enzymes. Enzymatic and microbial degradation of hair was observed to be preferential, starting with the least resistant components, in this sequence: (1) cell membrane, (2) endocuticle, (3 …
