PRETREATMENT REQUIREMENTS FOR LEATHER TANNING INDUSTRY WASTEWATERS

In this study, experiments are conducted on leather tanning industry w astewaters to evaluate efficiencies of alternative schemes of physical -chemical treatment with regard to pretreatment standards. Carbonation and protein removal are employed in addition to sulfide oxidation, ch romium precipitation, plain sedimentation and chemical precipitation. Two samples are used from two different tanneries processing cattlehid e. Results indicate that carbonation and protein removal have little e ffect on COD. TKN removal in protein precipitation is about 20 %. Plai n sedimentation is found to be as efficient as chemical precipitation for all parameters except chromium. However, as the results are evalua ted with regard to pretreatment standards chemical precipitation is su ggested to be the method of choice to meet the chromium as well as sus pended solids and sulfide standards.