H. Uemoto et H. Saiki, Nitrogen removal reactor using packed gel envelopes containing Nitrosomonas europaea and Paracoccus denitrificans, BIOTECH BIO, 67(1), 2000, pp. 80-86
Packed gel envelopes were constructed as simple, compact reactors for remov
ing nitrogen from wastewater. Each packed gel envelope consisted of two pla
te gels with a spacer in between. Nitrosomonas europaea and Paracoccus deni
trificans were co-immobilized in the plate gels, and ethanol, serving as an
electron donor for denitrification, was injected into the internal spaces
of the envelopes. The external surfaces of the envelopes were in contact wi
th ammonia-containing wastewater; the N. europaea present in the gels oxidi
zed the ammonia to nitrite aerobically. On the other hand, the internal sur
faces of the envelopes were in contact with the ethanol solution, which P.
denitrificans used to reduce the nitrite to nitrogen gas anaerobically. In
this way, the reactor using the packed gel envelopes removed ammonia from w
astewater in a single step. When artificial wastewater containing 200 mg-N/
L was treated using the reactor using eight envelopes, the ammonia was remo
ved by the reactor without accumulating nitrite or ethanol. This simple sys
tem exhibited high rates of nitrification (ammonia to nitrite; 1.9 kg-N/day
for 1m(3) of reader volume) and nitrogen removal (ammonia to nitrogen gas;
1.6 kg-N/day). It is presumed that these high rates were achieved as a con
sequence of cooperation between the N, europaea and P. denitrificans presen
t in the gels and the efficient uptake and exhaust of gases leading to the
smooth conversion of ammonia to nitrogen gas. (C) 2000 John Wiley & Sons, I
nc.