Summary
In drinking water disinfection, the presence of natural organic matter (NOM) in water leads to the formation of chlororganic disinfection by-products which are of substantial toxicological relevance. NOM also contains substances which may be exploited by bacteria, thereby contributing to the reinfection of the drinking water system.
In the light of these considerations, a combined research project was intended to clarify the influence of advanced oxidation processes upon NOM. The object of this subproject was the determination of the impact of oxidation using advanced oxidation processes (AOP), in comparison with conventional ozonisation technology. Key elements for analysis were therefore as follows:
- the degradation of trace materials, specifically diuron and ethylenediaminetetraacetic acids (EDTA);
- the impact of oxidation processes upon the behaviour of water during its service life, specifically the tendency towards reinfection and the formation of disinfection by-products.
To this end, laboratory trials and small-scale industrial test series have been conducted in cooperation with water utility companies. In these trials, the peroxone ozonisation process has been compared with the ozone/UV process and the hydrogen peroxide/UV process.
Results:
- The performance of the peroxone process for the degradation of EDTA and diuron was equivalent to that of ozonisation, with equal energy consumption. Lower levels of degradation were achieved by the ozone/UV process and the hydrogen peroxide/UV process.
- The most substantial reduction of precursors for disinfection by-products is achieved by ozonisation.
- Potential for reinfection after the application of AOPs has been lower than that observed after ozonisation.
