3. Results and discussion
3.1. Effects of flow rate on specific growth rate
For non-MFC perfusion biofilm systems in steady state and carbon-energy
(C/E) nutrient-limiting conditions, an increase in supply
rate has been demonstrated to cause a proportional increase
in l, up to a critical flow rate (CFR), where maximum specific
growth rate (lmax) is achieved (Gilbert et al., 1989). Results
(Fig. 1) indicate that MFC systems can also exhibit such behaviour.
Steady states are demonstrated by constant power output, e.g.
42.29 ± 0.06 lW over 8 h under setting 3, indicative of a stable
metabolic activity (see Inset graph, Fig. 1). Separated effluent samplings
(see A–C in Inset graph, Fig. 1) exhibited near-identical
OD540nm (0.563 ± 0.002, 0.561 ± 0.003 and 0.560 ± 0.002, respectively;
1=4 PBS dilution in all cases). Viable counts then confirmed