ABSTRACT
Bench-scale (batch) studies have been conducted, using a 60Co-γ irradiation system, to simulate the high-energy electron beam flow-through process, for the removal of natural organic matter in groundwater. The results indicate that 60Co-γ irradiation, or the high-energy electron beam process, would effectively remove natural organic matter, also referred to as disinfection by-product precursors, from natural waters as a first step in drinking water treatment. This conclusion is based on a significant reduction in dissolved organic carbon concentration in the treated samples when compared to the untreated control. The ultraviolet/visible (UV/vis) spectra from 200 to 500 nm showed a significant reduction in absorption in the region below 400 nm with increased treatment, indicating that the nature of the organic matter in the samples had also changed considerably. The addition of a relatively high concentration of chlorine to samples after treatment resulted in a marked reduction in total trihalomethane (THM) concentration when compared to those in the chlorinated, no-dose control. The THMs were determined after a 144-h reaction time. The reduction in THM formation, in the irradiated samples, indicated that free chlorine could be used in the normal disinfection concentration range, 1 mg l−1, without fear of exceeding disinfection by-product maximum contamination levels (MCLs) mandated under the Safe Drinking Water Act.
