Since the tidal combined wastewater is corrosive due to
the high salt content, the inner surface of the experimental
equipment was coated with corrosion preventive material.
The overall experimental equipment framework shown in
Fig. 2 was built of steel sheet by welding. The active
filler, which used the waste oyster shells from the nearby
seashore, had a depth of 2.6 m. The operation and optimization,
the parameters were: hydraulic retention time 3.6
hr; back flush water volume 30 m3/hr; gas:water ratio 5:1.