Spacer vibration for fouling control of submerged flat sheet membranes

In this study, a novel turbulence promoter based on vibrating spacers was investigated to control fouling in a submerged flat sheet membrane filtration system. The impacts of spacer types (1-D, 2-D, and 3-D), parallel distance of spacers to the membrane, vibration frequency and amplitude, and intermittent vibration interval on membrane fouling potential were examined. The results showed that vibration of 3-D spacers (sinusoidal geometry) could achieve up to 48% and 25% more fouling reduction than 1-D (flat plate) and 2-D (flat plate with grooves) spacers respectively when the spacers were located at a distance of 0.1 mm to the membrane. Increasing vibration frequency of the 3-D spacer from 1 to 2.5 Hz and increasing amplitude from 0.8 to 2 cm improved membrane fouling control efficiency by 33% and 34% respectively. The improved membrane performance was attributed to combined effects of the enhanced turbulence kinetic energy associated with back-transport of foulants and shear rate on the membrane surface as illustrated by the three-dimensional computational fluid dynamics (3-D CFD) simulations. An experimental and power consumption comparison of spacer vibration and gas sparging for fouling control was also performed. This study highlights the feasibility of vibration spacers in enhancing submerged flat sheet membrane performance.