Comparison of conventional technologies and a Submerged Membrane Photocatalytic Reactor (SMPR) for removing trihalomethanes (THM) precursors in drinking water treatment plants

• Evaluation of several technologies for the reduction of THMs in drinking water
• Ozonation shows low removal THM percentages of 40–50%,
• Membrane photocatalysis with TiO2 and activated carbon provide about 86% removal of THM.
• The addition of synthetic HA increases the ratio of bromo derivatives to chloroform.
• Taguchi's parameter design and statics (ANOVA) was used to optimize the systems.

This work evaluates the feasibility of several technologies for the removal of trihalomethanes (THM) precursors, usually humic substances found in real surface water, which are transformed into these potential carcinogens (THMs) during the further disinfection by chlorination. The aim was to compare, an Activated Carbon Bed (ACB), an Ozonation Reactor (OR) and a Submerged Membrane Photocatalytic Reactor (SMPR) with TiO2/UV in terms of reduction efficiency of these THM precursors after chlorination. Taguchi's parameter design methodology was selected to study the most relevant factors that might influence the removal of THM precursors with each technology keeping the number of experiments at minimum. According to the study, OR showed low removal percentages of THM precursors (of 40–50%) while SMPR and ACB were more efficient technologies. SMPR achieved 86% removal of THM precursors when operating at the optimal conditions of TiO2 catalyst concentration of 0.5 g L− 1 (type PC500® from Cristal Global). ACB attained the 87% removal of THM precursors when Filtracarb® CC60 8 × 30 (steam activated mineral coal) was used with a hydraulic retention time of 15 min.