Development of conventional ammonia free deliming agents in leather manufacturing in regarding the environmental pollution control

Environmental pollution is a major concern for leather industry. During leather processing, a large amount of waste is generated and their disposal into water bodies without proper treatment has a detrimental effects on environment. Tannery effluent is composed of several kinds of liquid waste: soak, lime, delime & bate, pickle & chrome. Deliming is one of the important steps in leather processing which is mainly based on ammonium salts. In conventional deliming process, a significant amount of ammonia is released which leads to further demand for critical wastewater treatment. Ammonia gas is highly soluble in water and responsible to create adverse environment for aquatic life. In this research work some weak organic acids like tartaric acid, propanoic acid, lactic acid, salicylic acid and para-hydroxy benzoic acid were used as deliming agent to decrease the pH of the reaction mixture as well as to reduce pollution load in tannery waste water. Deliming efficiency of used weak acids, physico-chemical properties of tannery effluent and physical properties of leather such as tensile strength, tear strength, lastometer test, water vapor permeability, flexing endurance and color fastness were comparable with the conventional delimed leather. The experimental results showed that the significant amount of pollution load as well as the costing of finished leather processed by developed deliming agent was significantly reduced although the quality of leather remain similar or better than conventional method.