Improvement of anaerobic treatment of tannery beamhouse wastewater by an integrated sulphide elimination process

Abstract

Sulphide, and especially the undissociated form, hydrogen sulphide, is inhibitory to anaerobic wastewater treatment processes. Tannery beamhouse wastewater contains high concentrations of organic material which make an anaerobic treatment favourable, but it also contains high concentrations of sulphide which cause difficulties for anaerobic treatment. The success of an anaerobic treatment will depend on reliable elimination of the sulphide. In batch tests stripping was the most effective process for sulphide removal compared to precipitation. The chemical-physical COD removal caused by the stripping was negligible, while precipitation caused a COD-removal of 26%. Also, anaerobic degradation velocity was higher if sulphide was removed by stripping. In fixed bed reactors operated continuously, stripping was shown to be a reliable method for eliminating hydrogen sulphide toxicity. Hydrogen sulphide caused an inhibition of 0.2% per mg 1−1 for methanogenic bacteria. Acidogenic bacteria were not inhibited by hydrogen sulphide. The gas-liquid equilibrium was shown to deviate from theoretical values taken from literature.