Improvement of Unhairing Operations in Tanning Process in Sudanese Tanneries

The negative environmental impact of the leather processing has been regarded as an inevitable consequence of that activity. In addition to high water consumption, soaking and liming with conventional unhairing method is one the most polluting part of the entire process of leather manufacture. The hair-save process proposed in this research utilizes conventional chemicals normally used in the unhairing process, but the hair fibre is firstly partially immunized by an alkali (lime) to be subsequently removed by the action of sulphide and ultimately recovered by filtration. The proposed process conducted in two trials in which 1.5% and 2.0% sodium sulphide of the hide’s total weight were used, the process conducted had a significant reduction of the pollution load in comparison with the conventional unhairing in terms of BOD, COD and sulphide load. Results showed decrease in BOD, COD and sulphide levels by 12%, 70.9%, 71.7% in the first trial and 4.4%, 22.5%, 27.3% in the second trail respectively. The reuse of the recovered hair fibre in hair-save process is possible under certain conditions.