Changes in the surface properties and stability of biocolloids of a sludge system upon extraction of heavy metals

摘要

The influence of chemical and biological extraction of heavy metals on the stability of natural sludge sol, as well as on the wetting and electrosurface properties of its particles, is studied. The biological extraction of metals is found to result in hydrophobization of sludge colloids and reduce their negative charge. Heavy metal extraction destabilizes the sludge sol, the level of destabilization being maximum upon bioleaching. The presence of exopolysaccharides considerably stabilizes the sludge system; however, it weakly affects the system's stability after extraction of heavy metals.