ENHANCED REMOVAL OF HALOGENATED ORGANICS FROM INDUSTRIAL GROUNDWATER BY SEQUENTIAL UV/H2O2 TREATMENT AND CARBON ADSORPTION

The removal enhancement by a combination of UV/H2O2 degradation and GAC adsorption was investigated for the remediation of industrial groundwater heavily polluted by several halogenated organics. The UV/H2O2 process alone was able to remove all pollutants (90-97% in 30 min) but for the 1,2-dichloroethane, the most abundant one (initial concentration 25000 =ug/L), the residual concentration (760 ug/L) was much higher than that set by the current legislation (3 ug/L). The employment of UV/H2O2+GAC allowed to reach the target residual concentration. Interestingly, it was found that GAC adsorption capacity was greater than expected. This was ascribed to the decomposition of residual H2O2 on the GAC giving rise to the formation of hydroxyl radicals that removed the residual organics. Therefore, the second step of the process consisted of a combination of heterogeneous oxidation and adsorption. This is of relevance for lowering the operation cost of the groundwater remediation process