Tannery wastewater is one of the most pollution sources. It can cause environmental problems related to its high organic matter, suspended solids and chromium. Chromium (III) salts are the most widely used chemicals for tanning processes, causing the tannery wastewater to be highly pollutant with chromium. The main objective of this study is to investigate the pre-treatment of an actual Egyptian tannery wastewater using two systems; the first electrolytic system and the second physico-chemical system. The performances of electrolytic system at current of 10, 20, 30 and 40 A were discussed. Poor removal efficiencies of chemical oxygen demand (COD), total suspended solids (TSS), chromium (III), ammonia (NH4+ and sulfide (S2−) were obtained. In the second physico-chemical system, calcium hydroxide was used as a coagulant material for chromium precipitation and plain sedimentation was applied for reducing of COD, biochemical oxygen demand (BOD5) and TSS. The results demonstrate 98.8% removal of chromium, 31% removal of COD, 25.8% removal of BOD5 and 51.2% removal of TSS.

chromium (III), electrolytic, physico-chemical, pre-treatment, sedimentation, tannery wastewater
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© IWA Publishing 2009
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