PARAMETERS AFFECTING THE DEGRADATION OF BENZOTHIAZOLES AND BENZIMIDAZOLES IN ACTIVATED-SLUDGE SYSTEMS

It was found that benzothiazole, 2-oxybenzothiazole and 2-benzothiazol esulphonate were degraded in activated sludge systems. 2-Mercaptobenzo thiazole (MBT) was more resistant, although the first step in MBT degr adation seemed to be transformation to the sulphonate form. At higher MBT concentrations, it was transformed into a disulphide, which accumu lated in the sludge. MBT was also found to be mainly responsible for t he toxicity of rubber chemical waste-water towards activated sludges. It inhibited the degradation of the other heterocycles. Only at concen trations of around 20 ppm was MBT degraded. Mercaptobenzimidazole rank ed second in resistance to degradation.