Integration of ozone, UV/HO and GAC in a multi-barrier treatment for secondary effluent polishing: Reuse parameters and micropollutants removal.

Current studies tend to combine different advanced treatment technologies to reduce costs and increase efficiency. The objective of this work was to assess the combination of ozonation and UV/HO with activated carbon adsorption for the removal of effluent quality parameters and micropollutants from secondary effluent samples. The experiments were carried out using the following configurations: O + GAC + O (1); O + GAC + UV/HO (2); UV/HO + GAC + O (3); UV/HO + GAC + UV/HO (4). Configurations 1, 3 and 4 were the most efficient for organic matter removal, while configuration 1 had the lowest cost on laboratory scale. An additional ultra-filtration membrane unit (UF) was tested at the end of configuration 1, which was optimized in terms of ozone doses for the removal of three organophosphate micropollutants in ultrapure water (TNBP, TCIPP and TPHP at 10 μgL). The best cost-effective configuration of this treatment train was the one using 1 mg L of ozone before and after GAC, which achieved around 100% of micropollutants abatement. The role of each treatment to the final micropollutant removal was also discussed, being the first ozone treatment responsible for about 15% removal of the mixture of contaminants, while GAC was responsible for an additional 80% removal. The complete treatment train reached almost 100% of contaminants removal (under detection limit of the method), as well as added security to the system. The achieved results were also compared to international reuse legislations, proving that the combination of O and GAC was an interesting option to achieve enough quality for some reuse purposes.