The main design parameters were: (1) There were two
bio-contact oxidation tanks. Each had a treatment scale of
2.5 × 103 m3/day and its shape was a rectangle with length
54 m, the width 24 m and the maximum depth 5 m. The
super-elevation was 0.5 meters. (2) The maximum depth
of back-flushing was 5.2 m. The organic pollutant loading
was 0.5 kg BOD5/(m3·day). The maximum aeration volume
was 196 Nm3/min and the aeration volume of each
bio-contact oxidation tank was 98 Nm3/min. The gas:water
ratio was 5:1.