Ku. Richter et G. Kruner, ELIMINATION OF NITROGEN IN 2 FLOODED AND STATICALLY PACKED-BED BIOFILTERS WITH AEROBIC AND ANAEROBIC MICROSITES, Water research, 28(3), 1994, pp. 709-716
Nitrogen removal efficiency was studied in a biofilter system consisti
ng of two flooded, statically packed bed biofilters (reactors A and B)
with aerobic and anaerobic microsites. During the experimental period
the reactors were integrated into a quasi-closed recirculated fish cu
lture system. In two experiments the degradation efficiency of dissolv
ed oxidized nitrogen compounds (NOx-N = N-2(-)-N+NO3--N) was measured
with and without oxygen supply. The oxygenation system consisted of si
licone membranes integrated into the filter-bed and supplied with tech
nical oxygen. The carbon source during the experimental period was met
hanol. The efficiency of NOx-N removal for reactor A (without oxygenat
ion) was 55%. With oxygenation, degradation efficiency of reactor A in
creased to a maximum of 86%. The maximum NOx-N degradation efficiency
of both biofilters (reactors A and B) reached 97% when connected in se
ries. Shifting of the bacterial populations as well as a linkage of th
e nitrogen transformations in the aerated and unaerated microsites are
discussed as possible reasons for the higher nitrogen removal rates.