The experimental units consisted of circular fiberglass tanks,
with a useful volume of 850 L and a bottom surface area of 1.0 m2.
A central aeration ring 20 cm in diameter (aero-tubeTM) was used
to maintain the solids in suspension and the oxygen concentration
at appropriate levels. The water temperature (29.0–30.0 ◦C)
was maintained with 1000 W submersible heaters. The tanks were
kept in an isolated room and received only artificial lighting with