ALKALI DEGRADATION OF PCB CONGENERS IN SEWAGE-SLUDGE

Alkaline saponification of sewage sludge may lead to the degradation o f PCBs with five or more chloro-substituents, HCB and DDE. Refluxing s ewage sludge with 2N KOH in methanol for 6 h did not cause degradation at 50 degrees C, reduced the concentration of hepta-to deca-CBs with approx. 50% at 70 degrees C, and even more at 90 degrees C. Refluxing with 4N KOH in methanol for 6 h efficiently eliminated hepta-to deca-C Bs, reduced hexa-CBs with around 50% and penta-CBs with around 30%. HC B was degraded faster than PCBs, whereas DDE was similar to penta-CBs.