2.4.4. Effect of hydrodynamic shear force on bacterial adhesion
To estimate the effect of the hydrodynamic shear force on the bacterial adhesion, the pre-formed biofilm on themembrane surfacewas exposed to the different stirring rates, and the detached bacteria were measured. After biofilm pre-formation using the same protocol as described in Section 2.4.1 at 1.50 MPa of the TMP and 100 rpm of the stirring rate, we continuously supplied 5-fold diluted FABmediuminto the cell at 1.50 MPa of the TMP and at various stirring rates from 100 to 300 rpm. The bacterial concentration in the condensatewaterwasmeasured by a pour platemethod to evaluate the bacteria detached fromthe membrane surface due to the shear force caused by stirring. Briefly, 1 mL of condensate water was added to 27 mL of warm FAB medium containing 1.5 g/L agar. The mixed solution was poured onto plastic plates, cooled at room temperature, and solidified. The prepared plates were incubated for 24 h at 30 °C, and the bacterial colonies on the plates were then counted.