Degradation of Benzothiazole by Ozonation and Adsorptive Ozonation

Benzothiazole derivatives are widely used as industrial chemicals; mainly as fungicides in the leather and wood processing industries, herbicides, components in automobile antifreeze, corrosion inhibitor in cooling systems, and in particular as vulcanization accelerators in the rubber industry1. Benzothiazole enters the environment from a variety of sources such as the leaching of rubber products, but particularly by routes associated with the manufacture and use of mercaptobenzothiazole (MBT) and MBT-based rubber additives2. Benzothiazoles can also be found in the environment as natural products, since these are included in molecular structure of vitamin B1. Their occurrence was observed not only in industrial and municipal wastewater but also in soil, estuarine sediments and surface water1. Several benzothiazole derivatives exhibit high toxicity. MBT shows the highest toxic effects on activated sludge; it is a carcinogenic compound and can cause allergic reactions, dermatitis, and initiate genetic damage in mammalian cells. According to Knapp et al.3, 7 mg L–1 BT causes 50 % and 54 mg L–1 BT causes 100 % inhibition of ammonia oxidation, while nitrate utilization is not affected4. Contaminants are removed from the environment without being destroyed or transformed in conventional physical treatment at high operating costs, while toxic residues are accumulated5. Application of biological process is inadequate when the wastewater contains highly toxic refractory compounds6. Commonly used urban WWT processes, including the removal processes of macronutrients are insufficient to remove specific synthetic substances. It is therefore necessary to search for combined chemical-biological or physicochemical-biological processes that can remove these substances efficiently and effectively. Among others, chemical oxidation with subsequent detoxification on biological sand filter or using granular activated carbon could be considered a perspective solution. Processes, which are widely studied and partially applied in practice include those using ozone, as well. Ozone is characterized by a high oxidation potential. Its basic disadvantages are, however, high operating costs. It is therefore necessary to explore methods to achieve more efficient ozone use. One possibility of increasing the efficiency of ozone utilisation is by means of the ozonation process parameters (pH, temperature, power generator, etc.). The combined process of ozone with other reactants/processes (UV, H2O2, catalytic ozonation, adsorptive ozonation) characterized by radical reaction mechanism, higher reaction rates and thus also higher efficient use of ozone appear more efficient. Degradation of Benzothiazole by Ozonation and Adsorptive Ozonation