During the initial stage, the acetate (25.3 mg L1) and propionate (15.2 mg L1) reached maximum
concentrations in the W2 microcosm (seen in Fig. S5 in SI), which was consistent with the highest sulfate removal rates
observed in the W2 microcosm (Table 1). Then, the VFAs concentrations in each microcosm decreased gradually with
time, and it was not detected in the middle and terminal stages.