Abstract
Water is becoming a strategic raw material and thus, protection of water resources belongs to priorities. Toxic substances need to be removed prior to the biological treatment stage in a WWTP. Biologically resistant substances flow through the biological treatment stage in a WWTP directly to water recipients, and can travel as far as to the underground water and drinking water sources. Taking into account the large volumes of these substances, their removal from ground water and water sources would be extremely costly. It is economical therefore to remove these already at their source or in a WWTP using separation or degradation processes. This paper deals with the possibility to use ozonisation for pretreatment of wastewater prior to the WWTP biological stage. Benzothiazole removal efficiency exceeding 95 % within 60 min. of ozonation was reached when combining ozonation with zeolite addition. Partially oxidised COD portion was significant in the first 15 minutes, followed by subsequent growth of mineralised COD portion.