We have evaluated the possibilities of waste water denitrification usi
ng volatile fatty acids (VFA) as the sole carbon and electron source i
n an activated sludge culture continuously fed with a mixture of aceta
te, propionate, butyrate and valerate. All the VFA were biodegraded in
denitrification conditions by a mixed adapted bacterial population wi
th 5 predominant different bacterial strains (Ochrobactrum anthropi, M
oraxella lacunata, Pseudomonas testosteroni, Paracoccus denitrificans,
and Pasteurella gr. EF4). The denitrification (20 mg N-NO(x) g-1 MES
h-1) and carbon consumption rates (60 mg C g-1 MES h-1) obtained in ba
tch conditions were the same for acetate, butyrate, valerate used alon
e or for a mixture of the 4. Propionate was almost not metabolized (3
mg N-NO(x) g-1 MES h-1 and 8 mg C g-1 MES h-1).