Pilot-scale composting and biodegradability of bovine hair

Abstract

The aim of this study was to develop process factors favourable for composting as an environmental-friendly and sustainable management for solid tannery hair waste. The experimental process conditions developed to sustain thermophilic microbial flora, responsible for degrading highly resistant organic materials, were: temperature 49 C, moisture 55% RH, pH 7 and a carbon to nitrogen ratio of 35: 1. The biodegradation and structural modification of the substrate was assessed using scanning electron microscope. The results show that under these experimental conditions hair was highly degraded. The biodegradation was observed to be selective starting with the most vulnerable components, ie (1) cell membrane (2) endocuticle (3) medulla, and (4) the cytoplasmic material and fibrillar components of the cortex, with the cuticle being most resistant. The degradation mechanism was identified as both biochemical and mechanical. The gradual decrease in carbon and nitrogen ratio indicated progressive stabilisation of the compost.