Algal Organic Matter Degradation by Chemical and Photo-Chemical Processes: a Comparative Study

Algal organic matter (AOM) in water reservoirs is a worldwide concern for drinking water treatment, once it is one of the main precursors for disinfection by-product formation. Oxidative processes have been widely applied in drinking water treatment to improve microalgae removal; however, there is little information about their performance for AOM degradation. In this context, this study aimed to evaluate the performance of hydrogen peroxide (H2O2), Fenton (H2O2/Fe(II)), and photo-Fenton (H2O2/Fe(II)/UV) processes for AOM removal. Low AOM removals (0.46 to 12.02%) were found using H2O2. The highest AOM removals for H2O2/Fe(II) (29.8%) and H2O2/Fe(II)/UV (67.0%) were obtained using 40 and 30 mg Fe center dot L-1 at 150 min, respectively. In general, high pH values decreased AOM removals for H2O2/Fe(II) and H2O2/Fe(II)/UV processes and increased them for H2O2 application. All oxidative processes had stabilized at 150 min, and further reaction time did not significantly increase the AOM removal. Trihalomethane formation potential (THMFP) was evaluated using the optimal conditions of each process. Reductions of THMFP were 42.0, 74.0, and 83.4% for H2O2\, H2O2/Fe(II), and -H2O2/Fe(II)/UV, respectively. This study showed the potential of oxidative processes to complement AOM removal by the traditional technologies applied in water treatment. Further studies are required to optimize the parameters involved in the process to improve the cost-effectiveness of the processes and applicability in water treatment.