Role of carbohydrases in minimizing use of harmful substances: leather as a case study

Leather processing is an important industrial activity. Globally about 2.0 billon sqmt of leather is produced annually. Conventional cleansing operations carried out prior to tanning generate large amounts of waste. Among them dehairing and fibre opening process (reliming) generate large amount of effluent containing hazardous substances and alkaline sludge, resulting in high negative impact on the environment. In this study, both these pre-tanning process steps have been combined using a cocktail of carbohydrases along with optimum quantity of chemicals to minimize the environmental concerns. Carbohydrate and proteoglycan removal were chosen as the parameters of study for efficacy of unhairing and fibre opening. The morphology features of skins were analysed using scanning electron microscopy and histology. Pollution load of the enzyme aided process effluent was determined and compared with conventional process. Findings of the study indicate complete elimination of reliming process step is possible when both unhairing and fibre opening is carried out simultaneously using carbohydrases as an adjunct. Reduction in use of harmful sulphide and lime up to 40% apart from substantial saving in time and water input is the major outcome of the present work.