The ozone and biological activated carbon (Ozone/BAC) process is known for being able to provide a wide range of drinking water treatment benefits including destruction of organic contaminants such as taste and odour compounds, algal toxins, pesticides and herbicides. However, its ability to remove disinfection by-product (DBP) precursors is often found to be dependent on water characteristics. This paper presents results from our recent Ozone/BAC pilot plant investigation. The main objective of this work was to assess the efficacy of this process in reducing DBP precursors for one of the most challenging raw water sources in Australia. The pilot plant was operated in the intermediate ozonation mode, with its feed water drawn from the settled water of a full-scale treatment plant operating in the enhanced coagulation mode. The Ozone/BAC process was found to be capable of providing significant removal of DBP precursors and hence reductions in trihalomethane (THM) formation. The removal efficiency was however found to be highly dependent on the empty bed contact time (EBCT) used, with longer EBCTs yielding significantly better removal. Our results highlight the importance of conducting pre-design testing to prove the suitability of this process for DBP precursor removal for a specific water to be treated.
Chemeca2008. Chemeca2008: Towards a Sustainable Australasia (Newcastle, N.S.W. 28 September - 1 October, 2008) p. 221-231