The water was continuously aerated using compressed air root
blowers to maintain the dissolved oxygen (DO) of N6mgL−1
in both
the BFT and RAS tanks. One root blower (135 W) was used for the
three tanks in the RAS tanks. Considering the high suspended-solid con-
centration, the high oxygen consumption that was required by the
adding of the carbon sources, and the strong mixing intensity required
in the BFT tanks, two root blowers were used in the three BFT tanks.
The pH in both systems was maintained at a range of 7.0–7.5 using
NaHCO3. A water temperature-control device was used to maintain the
temperature of both systems between 24 and 26 °C. Furthermore,
waterwas added daily to account for evaporation loss and biofloc remov-
al, and a simulated natural photoperiod (12 L:12D) was applied. The ni-
trification function in biofilters was already established in the RAS and
the biofloc was already developed in the BFT tanks (mixed liquor
suspended solids (MLSS) N150 mg L−1
) before the tilapia were put in.