Investigating the effect of pretreatment on bioleaching of heavy metal contaminated sludge using sulfur oxidizing bacteria

Abstract

In this study, a technologically and economically biological method called bioleaching was conducted using four bacteria Micrococcus luteus, Ralstonia pickettii, Bordetella trematum, and Lysinibacillus to degrade heavy metals from sewage sludge. The effects of pretreatments on the efficiency of bioleaching process were examined. These pretreatments were fresh sludge, dried sludge, and sterilized sludge. The highest Cr leaching efficiency in sterilized sludge, dried sludge and fresh sludge is 68.44%, 76.26%, 90.83% as compared with initial concentration respectively. Besides, the highest Zn bioleaching efficiency in sterilized sludge, dried sludge and fresh sludge is 44.32%, 88.06%, 95.92% as compared with initial concentration respectively. In which, the most effective metals solubilization was achieved with fresh sludge due to the good adaptability to natural condition. Key words: Sulfur Oxidizing Bacteria (SOB), Bioleaching, Pretreatment