Empirical modeling of bromate formation during drinking water treatment using hybrid ozonation membrane filtration

The effect of the nature of the membrane surface, the presence of hydroxyl radical scavengers, and temperature, on bromate formation in a hybrid ozonation membrane filtration reactor was studied. The presence of tertiary butyl alcohol, a hydroxyl radical scavenger, suppressed the indirect bromate formation pathway and less bromate was formed. Bromate formation was less with the Mn oxide coated membrane than when using the uncoated TiO2 membrane. As the temperature was increased, bromate formation was enhanced, which was attributed to faster reaction rates. An empirical model was developed to predict bromate formation in a hybrid ozone-ceramic membrane filtration system. The model takes into account the effects of important experimental variables including initial bromide concentration, inlet ozone injection mass rate, pH, temperature, and reaction time. The coefficients in the model were determined using multiple linear regression with logarithmic transformations. The model indicated that bromate formation was favored at high bromide concentration, ozone dose, pH, and temperature. Good correlation was achieved between the model predictions and the experimental data.

► Bromate formation was suppressed with a Mn oxide coated membrane.
► OH radicals were formed on the membrane surface even at low pH.
► Bromate formation can be reduced by increasing the molecular weight cutoff and/or the permeate flux.
► Bromate formation was predicted in a hybrid ozone–membrane system using a new empirical model.
► The model showed that bromate formation was favored at high Br−, ozone dose, pH, and temperature.