Effects of surface skewness on local shear stresses, biofilm activity, and microbial communities for wastewater treatment

This study's objective was to assess attachment surface skewness (asymmetric surface height variation) effects on biofilm development. 3D printed molds were used to create surfaces with 300 mu m features to provide opposite skewness but identical roughness values. Surfaces with negative skewness had consistently greater nitrite oxidation and biomass growth than other surfaces during biofilm development when studied in annular bioreactor systems. CFD modelling predicted local shear stress differences that could explain experimental results. 16 s rRNA gene amplicon sequencing revealed population differences, including relatively high Acinetobacter and Terrimonas fractions on the negative skew surfaces, and PCoA analyses indicated the flat surface populations diverged from the skew surfaces by the study's end. The results suggest skewness is particularly important in systems where biofilms have not overgrown surface features, as in system startup, thin biofilms, and shorter time frame studies, which includes much previous microbial attachment research.

Automated summary

The study showed that surface skewness has significant impacts on biofilm development, with surfaces with negative skewness promoting nitrite oxidation and biomass growth. Analysis of 16s rRNA gene sequencing revealed differences in bacterial populations, and PCoA analysis indicated divergence between populations on skew and flat surfaces.