Abstract

Due to the high content of pollutants in their output streams tanneries have a negative environmental impact. A high content of organic matter (BOD 5and COD) sulphide and chrome bearing effluents and a high quantity of organic solid waste characterise the output streams of a tannery. In developing countries —where chrome tanning is the prevailing technology and effluent and waste treatment is only rarely practised—tanneries represent a great environmental problem.

As part of the European Community INCO-DC project “EILT” (Reduction of Environmental Impacts of Leather Tanneries) an extensive input/output analysis was carried out at the Chilean tannery GACEL S.A.

On the one hand the actual resource consumption and generation of solid waste and effluents could be quantified. Per ton of wet salted hide (tWSH)•—the base of this work -about 500 kg of chemicals and 62m3 of fresh water are consumed. From this ton of input material 187 kg of grain leather and 89kg of split leather are produced, about 109 kg of split are sold in the wet blue stage. 734 kg of solid waste (chromium containing and non-chromium containing) are generated and about 57 r3n of effluent are discharged.

This input/output analysis was the basis of pollution prevention opportunities which have been devel oped. Stress was put on “simple and economic” opportunities which can be implemented in the prevailing difficult economic situation.

These suggestions deal with the extensive fresh water consumption (reuse of rinsing waters; counter current rinsing; changing of paddle technology to drum technology in the beamhouse) and the treatment of the highly contaminated effluent streams (implementation of a screen to reduce the high B5OD and COD value, start-up of the existing sulphide treatment plant). In regard to solid waste, biological treatment of the non-chromium containing fraction was suggested. This measure would reduce the quantity of solid waste by about 75%.

However, implementation of the suggestions made by the INCO-DC working group will still take time and will depend on the impact of legal restrictions and an active interest in reducing environmental impact