Hybrid membrane processes for the treatment of surface water and mitigation of membrane fouling

Abstract

Membrane-based processes are well recognized treatment methods for waters and wastewaters of different origin. However, the biggest drawback connected with membranes’ filtration is their severe fouling, which deteriorates the process effectiveness. Combining membrane filtration with another water/wastewater treatment method in a hybrid process is a promising way of improving the overall membrane operation. In this study an approach of combining ceramic membrane filtration with chemical oxidation processes, i.e. ozonation and ozonation combined with hydrogen peroxide, is presented. A flat sheet ceramic microfiltration membrane of a submerged type has been used in the experimental unit. Ozone–oxygen gas mixture was introduced to the system by appropriate ceramic gas spargers and two flow rates of the gas mixture were tested: 0.1L/min and 0.2L/min with corresponding ozone dosages of 2.5 and 5.0mg O3/min of ozone addition, respectively. The water treated in this experimental system was a simulated (contaminated) surface water with Total Organic Carbon (TOC) content of 8 (±0.3) mg/L and turbidity of 20 (±0.5) NTU. The collected permeates were evaluated for selected pollution parameters, such as turbidity, TOC, UV254 absorbance and SUVA values. HPLC analysis has been performed for the calculation of molecular weights of products in the permeates obtained during hybrid processes. The fouling of membrane was evaluated by the calculation of Fouling Index (FI) and monitoring changes in the Trans Membrane Pressure during membrane operation. The obtained results indicated that the membrane fouling was mitigated during the hybrid processes, increasing the overall efficiency of membrane microfiltration for the treatment of contaminated surface water.