Pre-coating of stainless-steel mesh support material with wastewater treatment plant sludges in a dynamic membrane filtration process

Abstract

This study focuses on wastewater treatment plant sludges to be deposited on large aperture meshes. In a column reactor that is filled with treatment plant sludges, a series of batch experiments were performed with varying sizes of stainless-steel mesh modules (75 to 300 μm) as a support media to form a dynamic membrane. Primary, secondary, and polyelectrolyte-added sludges were used both individually and in combination to investigate the performance (filterability, permeate quality, and dynamic layer formation ability) of the varying pore-size meshes at high fluxes. The results were superior when primary and secondary sludges were combined in the creation of a dynamic cake layer, as opposed to individual sludge usage. Mesh sizes were shown to have no effect on performance, providing turbidity of <10 NTU for a short duration (10 min) of filtration. Cake formation rates were calculated as 23.0 NTU/min, 19.48 NTU/min, 7.62 NTU/min, and 6.94 NTU /min for 100, 150, 200, and 300 μm support meshes, respectively. For the first time in literature, effluent water turbidity decreases to <5 NTU for 300 μm support mesh at high fluxes. Scanning electron microscope images showed that fibers that may originate from the primary sludge could enhance the formation of stable cake layer. This study is important for creating high-performing dynamic membrane filtration on large aperture meshes, which can be used as a cost-effective and reliable filter for wastewater treatment.