Respiration rate ofthe water column, which is used as an indicator
of biological activity of the microorganisms (Metcalf and Eddy,
1991), was no different between MO and RB tanks, suggesting that
both organic sources had been used as substrate. Despite this, the
higher dose offertilizer increasedVSS, but only in the water oftanks
fertilized with rice bran. Therefore, although the water respiration
rate in MO-treated tanks increased with the higher fertilization