Immobilization of activated sludge for the degradation of phenol

Activated sludge obtained from a phenol treatment plant was immobilized by entrapment in Ca-alginate, chemical or radiation polymerised polyacrylamide, agarose and hen egg white. All these techniques resulted in immobilized sludge preparations retaining their phenol degrading ability. Comparatively Ca- alginate entrapped sludge retained maximum activity. The immobilized sludge could be reused over 12 batches without loss in phenol degrading ability. Immobilization of the sludge provided protection to the micro flora and could efficiently degrade phenol concentrations over 1000 ppm better than the free sludge.