Fig. 7. Two-stage decay process of the logarithm of soluble reactive phosphorus (SRP) at 25°C during (a) I_t O_t flow path configuration and (b) I_b O_t flow path configuration. I_b, inflow port at the bottom of the flume; I_t, inflow port at the top of the flume; O_t, outflow port at the top of the flume.