The experiments were performed in two 4.5 L sequencing batch reactors. Both had an internal diameter of 8 cm and a liquid filled height of 60 cm (=3 L working volume) and were maintained at a temperature of 24–26 C (optimal temperature for tilapia culture). The microbial biomass was intensively mixed by means of two fine bubbling diffusive airstones. The first was placed at the bottom of the reactor and the second was placed at half of the water height.
Each reactor was supplied with air by means of an 8W air pump (Rena Air 400, Rena, France). The reactors were initially subjected to consecutive cycles of 3 h comprising an anaerobic feeding phase of 60 min, followed by an aerated reaction phase of 1 h 52 min, a settling phase of 3 min and 5 min withdrawing the effluent (deKreuk and van Loosdrecht, 2004). From day 15, the feeding phase was aerated as well. After settling, 2.5 L of the supernatant was removed. Thus, the reactor selected for microbial biomass settling faster than 10 m h1 and had a water exchange ratio of 83% per cycle. Biofilms growing on the walls of the reactors were removed by means of manual aquarium cleaning magnets.
The experiments were performed in two 4.5 L sequencing batch reactors. Both had an internal diameter of 8 cm and a liquid filled height of 60 cm (=3 L working volume) and were maintained at a temperature of 24–26 C (optimal temperature for tilapia culture). The microbial biomass was intensively mixed by means of two fine bubbling diffusive airstones. The first was placed at the bottom of the reactor and the second was placed at half of the water height.
Each reactor was supplied with air by means of an 8W air pump (Rena Air 400, Rena, France). The reactors were initially subjected to consecutive cycles of 3 h comprising an anaerobic feeding phase of 60 min, followed by an aerated reaction phase of 1 h 52 min, a settling phase of 3 min and 5 min withdrawing the effluent (deKreuk and van Loosdrecht, 2004). From day 15, the feeding phase was aerated as well. After settling, 2.5 L of the supernatant was removed. Thus, the reactor selected for microbial biomass settling faster than 10 m h1 and had a water exchange ratio of 83% per cycle. Biofilms growing on the walls of the reactors were removed by means of manual aquarium cleaning magnets.
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