Ammonia-reduced Deliming using Glycolic Acid and EDTA and its Effect on Tannery Effluent and Quality of Leather

Abstract

In leather processing, deliming is traditionally carried out usingammonium salt which generates a large amount of ammonia intannery waste water. This may result in water pollution as well astoxic effect on aquatic organisms. This research work is anattempt to develop an alternative deliming agent to minimizethe pollution load o tannery waste water. The current researchwas performed using mixture of 90 wt. % of glycolic acid and 10wt. % of ethylenediaminetetraaceticacid (EDTA), which evolvesno ammonia and relatively inexpensive. Deliming value, buffercapacity, calcium solubility and penetration in limed pelts of thedeveloped deliming agent were determined to assess itseffectiveness. Sulphide content, Ammonia Nitrogen (NH3-N)Content, Biochemical Oxygen Demand (BOD) and ChemicalOxygen Demand (COD) values of the resulting discharge waterwere analyzed and examined in contrast with traditionallydelimed discharge water. The developed deliming agent wasapplied on leather and its properties, such as tensile strength,elongation at break, tear strength, softness, chromium uptake,and morphological characteristics were compared toconventionally delimed leather as well as the standards.