We report the first published use of flood/drain laboratoryscale
gravel biofilters to remove nitrogen from saline aquaculture
effluent. The findings demonstrate that when water is recirculated
(treatments 2 and 3) flood/drain biofilters improve TKN,
organic nitrogen and ammonia removal but not nitrate or
nitrite removal when compared with conventional permanently
submerged biofilters. Conversely, in permanently submerged
biofilters the concentration of nitrate and nitrite in the outlet
water was lower than flood/drain biofilters. These results
indicate a higher nitrification efficiency in the flood/drain
biofilters and higher denitrification efficiency in the submerged
biofilters, regardless of the duration of the refilling/displacing
period.