The concentration of ozone in the feed mixture was determined
prior to the experiments and 10.0–100.0 mg/L ozone dosages were
applied. The ozonated effluent was stored and kept at least 24 h in
the middle tank, where residual ozone from effluent was purged by
bubbling nitrogen in order to make sure that no dissolved ozone
was presented. The pH of ozonated effluent was also controlled
in the range of 6.5–7.5, and nutrients (CaCl2, MgSO4, FeCl3, and
phosphate buffer solution) were added into the middle tank to sustain
the growth of microorganisms in the subsequent BAF column
before ozonated effluent was pumped.