Abstract

This study evaluates the use of water in processing hides into leather. It investigates the environmental impact on water resources of tanneries in Rio Grande do Sul State, evaluating the water demand and concentrations of certain chemicals in the wastewater discharged from the beamhouse, tanning and retanning processes of this industry.

A questionnaire was formulated which was intended to identify water management problems in tanneries, and the possible alternatives available to tanneries aiming at their improvement. A simple and objective application called IRGO (insufficient, regular, good and optimal) was developed. The IRGO was applied to 10 tanneries. After completing the questionnaire, the tanneries could check how removed they are from an ideal tannery and ascertain which actions must be taken to improve their performance.

The results showed that there is a large demand for water in the process and little water is re-used.

The most conventional liming process employs sulphide, lime and amine and recycling is already applied to this operation in the state. The steps of washing, deliming and the float itself use large quantities of water, although the majority of the tanneries do not use ammonia in deliming. The tanning procedure most used employs chrome III without recycling. In relation to retanning, studies need to be carried out aiming to increase the efficiency of the absorption of chemicals. The wastewater treatment plants are satisfactory due to the requirements of the environmental organizations.