Synergistic effect of alternating current-based electric and acoustic fields on flux recovery in crossflow microfiltration of synthetic wastewater

[Display omitted] •A new electro-acoustofiltration device has been developed for simultaneous application of alternating current electric field and acoustic field for specific flux recovery.•Specific flux recovery in the presence of both fields is greater than numerical sum of fluxes (i.e., 1 + 1 > 2) due to AC electric field alone or acoustic field alone.•AC electric field and acoustic field have critical fields beyond which improvement in specific flux or fouling mitigation are minimal.•Specific flux recovery during simultaneous application of electric and acoustic fields depends on foulant type and composition, feedwater pH, and electric field and acoustic field parameters. The main objective of this study was to investigate the feasibility of synergistic recovery of flux (i.e., 1 + 1 > 2) and fouling mitigation, in the presence of simultaneous application of alternating current (AC)-based electric and acoustic fields during crossflow microfiltration of synthetic wastewaters. We, first, designed a novel crossflow microfiltration apparatus to investigate synergistic effect of AC electric and acoustic fields; secondly, conducted fouling studies on (a) synthetic wastewater alone and (b) synthetic wastewater containing 1.2 × 108 particles/L of silica particles (300 nm SiO2), Micrococcus luteus (500–1000 nm), or a mixture of SiO2 and M. luteus at 50 % each by count, respectively; thirdly, studied the effect of several parameters, including AC electric field strength, acoustic field frequency, foulant type and composition, and pH of synthetic wastewater on fouling; and finally, assessed the significance of synergistic effect of fields on flux recovery using 22 two-level factorial analysis. Results revealed that the application of combined fields recovered 21 % of clean water flux which is significantly higher than those obtained by electric field (4 %) or acoustic field (6 %) alone. The non-linear relationship between flux recovery and each test parameter suggested that the effectiveness of field-assisted membrane processes is determined by multiple competing or mutually enhancing mechanisms − such as electro- and acousto-kinetics, and adsorption and agglomeration of particles − which were proposed to explain the synergistic effect of fields on flux recovery. This study demonstrated the combined AC electric and acoustic fields can synergistically amplify the flux recovery in crossflow microfiltration of synthetic wastewaters.