Combined catalytic ozonation and membrane system for trihalomethane control

• Catalytic ozonation promotes membrane permeate flux recovery.
• Increasing ozone and catalyst dosage enhances permeate flux recovery.
• The percentage removal of TOC and UV254 increased as the catalyst dosage increased.
• The gas flowrate and catalyst dose positively influence the reduction of SDS THMs.

Water containing humic acid causes membrane fouling and the formation of disinfectant by-products, such as trihalomethanes (THMs), after chlorination. In this research, heterogeneous catalytic ozonation was used with a ceramic membrane system to investigate its effect on the prevention of membrane fouling and the formation of THMs. Ozone and nitrogen gases were injected into the membrane system with or without TiO2, which was used as the catalyst. The effects of operating conditions such as gas flow rate, catalyst dosage, and ozone dosage were investigated. The results show that permeate fluxes recovered up to 78% and 93% when ozonation alone and catalytic ozonation were applied in the hybrid system, respectively. The recovery rate of permeate flux increased with increasing ozone gas flow rate. The THM concentrations in the chlorinated permeate water significantly decreased when TiO2 and ozone gas were injected into the hybrid system. An increase of TiO2 dosage in catalytic ozonation resulted in a decrease of THM formation in the chlorinated permeate water. This study shows that the proposed hybrid system can be effective for permeate flux recovery and THM formation control.

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