The impact of cell metabolic activity on biofilm formation and flux decline during cross-flow filtration of ultrafiltration membranes

One significant challenge to membrane filtration technologies is membrane fouling causing pressure drop, flux decline and eventually significant cost of membrane replacement. The objective of this research was to determine the impact of metabolic activity as measured in adenosine triphosphate (ATP) concentration of the pure culture of biofoulants on the membrane biofilm metabolic activity, biofilm formation rate, and operational flux decline. Our results showed that after 10–12 h of filtration, the biofilm ATP levels reach an equilibrium concentration (avg. 8 amol/cell) and do not appear to be related to biofoulant ATP levels from cells harvested in the late exponential growth phase regardless of initial ATP level. However, the bacterial growth phase affected the ATP activity of cells and membrane biofilms formed from biofoulants in the lag and stationary phases of growth contained similar levels of activity, and the exponential phase cells resulted in significant higher activity. Flux decline does not appear to be related to metabolic activity of the biofoulant or biofilm following 24 h of filtration but notably, there was much less flux decline when the biofoulant cells were inactive.

► Physiological state of biofoulant impacted biofoulant activity.
► Biofoulant activity level did not correlate to biofilm activity level.
► Biofilm activity level was not a good indicator of flux decline.
► Stationary phase samples had more and unique EPS.
► Inactive cells resulted in the least amount of flux decline.