The present investigation was carried out in the aim of developing a n
ew fixed-culture nitrification-denitrification scheme short-circuiting
the production of nitrate ion. The analysis of the behaviour of a sub
merged biofilter is reported for the development of a denitritation pr
ocess. The results obtained show that the denitritation reaction takes
place in the submerged biofilter according to apparently zero-order k
inetics with a maximum nitrite removal rate of 2.1 kg NO2--N m(-3) of
liquid phase . d(-1), corresponding to a maximum volumic loading of 1.
1 kg NO2--N m(-3) of reactor . d(-1). The critical volumic loading app
lied (above which the denitritation yield fell) was 0.8 kg NO2--N m(-3
) of reactor . d(-1). The carbon requirement in the form of acetate wa
s estimated for denitritation as 0.84 kg soluble TOC . kg(-1)NO(2)(-)-
N eliminated. Biological sludge was produced at a rate of 0.69 kg dry
solids . kg(-1)NO(2)(-)-N removed. Finally, it was shown that the deni
trifying microorganisms adapted very well to a sudden input of nitrate
into the denitritation biofilter.