2.4. Biofouling experiments
2.4.1. Biofouling protocol
The biofouling experiment was carried out by filtrating the feed water containing nutrients for bacteria through a polyamide RO membrane with pre-adhered bacteria. Before each experiment and prior to inserting the RO membrane into the cell, the membrane test units were autoclaved. The outline of the biofouling experiment is shown in Fig. 2. Firstly,Milli-Q water and 5-fold diluted FABmediumwere continuously supplied into the cell for 15 min to stabilize the membrane conditions. The bacterial suspension was then supplied for 15 min and stopped for 45 min to allow bacterial adhesion to the membrane surface.Thiswas followed by supply of 5-fold diluted FABmediumand permeation by applying TMP for biofouling.
We investigated the effect of controlling the applied TMP and stirring rate in the cell on biofouling. The TMP and the stirring rate in the biofouling step shown in Fig. 2 were changed from 0 to 1.50 MPa with a constant stirring rate of 300 rpm and from 100 to 300 rpm (from 16.7 to 50.1 cm/s as maximum cross-flow velocity on the membrane surface) with a constant TMP of 0.75 MPa, respectively.