Hybrid ozonation-microfiltration system for the treatment of surface water using ceramic membrane

The aim of this work was the investigation of performance efficiency of a hybrid system, integrating two processes, i.e. membrane filtration and ozone oxidation, as a potential method for the contaminated surface water quality improvement and the mitigation of membrane fouling. Ozone-oxygen gas mixture at various flow rates (and corresponding ozone concentrations) was introduced into the experimental vessel by gas spargers, located at the bottom of vessel and producing fine gas bubbles. Ozone-oxygen gas flow rates ranged from 0.3 L/min to less than 0.05 L/min, while ozone amounts in the gas mixture added to the system varied from 6.6 mg to less than 1.1 mg O3/min of experiment, respectively. Ozonation and ceramic membrane microfiltration were performed simultaneously. Treated water samples were collected and analyzed for major quality parameters, i.e. turbidity, pH, UV254 absorbance and Total Organic Carbon (TOC) content. The permeates were also analyzed with the HPLC technique for the estimation of molecular weights of resulting humic acids oxidation products. The hybrid process of membrane microfiltration-ozonation resulted in substantial reduction of membrane fouling rate for all the examined concentrations and flow rates of ozone, while the quality of permeate varied, depending on the ozone concentration used. With the optimum ozone dosage the quality of permeate for single microfiltration and hybrid processes were similar, while the addition of ozone to the system resulted in a substantial fouling reduction.