Preparation of Sulphide-lime Unhairing Ratios for Pollution Load Reduction in the Manufacture of Shoe Upper Leathers from Tropical Goat Skins

摘要

Preparation of sulphide-lime unhairing tannery process was carried out using nine ratios-coded as A_I - A_(III); B_I - B_(III) and C_I - C_(III) with varied concentrations of sodium sulphide and hydrated lime. Result obtained through subjective tests and gravimetric method show differences in degree of unhairing, swelling and plumping of the pelts. The pH of wastewater generated from each ratio and weight increase of limed pelts, was observed and recorded. Analysis of pollutants from the wastewater was determined by parameters such as BOD, COD, and Sulphide generated from the wastewater. Results obtained show various levels of parameters from the studied ratios indicated that A-group had poor unhairing and liming properties. The C-group gave excellent properties but with higher pollution load. However, B_(II) (2.5% Na_2S with 2.0% Ca(OH)_2) and B_(III) (2.8% Na_2S with 2.5% Ca(OH)_2) in 200% float generated lower pollution level as determined by the parameters from their individual wastewaters. This was compared with the conventional (CTL) and that of the industry. The average sample wastewater collected from the industry indicated higher pollutants than the studied and CTL ratios. The study reveals that maximum utilization of reagents is a necessary technique for reduction of pollutants in the wastewater from sulphide-lime unhairing process known to generate 65%-70% of pollutants from the beam-house.