Study On The Removal Of Cr From Tannery Sludge By Sodium Hypochlorite

Leather tanning industry produce large amounts of tannery sludge, because it contains a lot of heavy metal Cr, sulfide and other substances, tannery sludge is as hazardous industrial solid waste. At present, the final disposal of tannery sludge are placed in landfills, burned in commercial incinerators, stack or used as building materials and compost, etc. Agricultural use is considered to be the most promising disposal. The main factors limiting agricultural sludge are the heavy metal, pathogen, parasite eggs and other substances. In this paper the author summarized the status of tannery sludge treatment and Proposed to put chromium leaching from tannery sludge by using of sodium hypochlorite.In this study, the tannery sludge from Guangxi Bin Yang factory were as experimental subjects, First we studied the single factor experiments and found that the main factors affecting experimental are the concentrations of sodium hypochlorite, liquid to solid ratio, reaction time, temperature, PH, lighting and so on. Secondly The Optimum technological conditions were studied by the orthogonal experiment. The results showed that100%of Cr(Ⅲ) in the tannery sludge was removed by treating with sodium hypochlorite at6%of the concentration of sodium hypochlorite, the liquid-solid ratio22g solution/g soil, temperature60℃, reaction time80min. In addition keeping out of the light and adding sodium hypochlorite step by step can reduce the loss caused by the decomposition of sodium hypochlorite, that will improve the leaching rate of Cr. Compared with the existing similar methods, this method does not need adjusting the pH value of the solution, the operation is more simple and convenient.