To 2.18, 2.09, 2.99 respectively, whereas in the

To accomplish the above, varying
quantities of immobilized NBC on wood powder were incubated in 1L seawater
having 15 g/ L salinity. Initially TAN was maintained at 10 mg/ L. Nitrification
was monitored in terms of per day TAN removal and NO2– N
production. On day 1, the TAN removal rates in the systems  inoculated with 0.1, 0.2, 0.3, 0.4, 0.5, 0.6,
0.7, 0.8, 0.9, 1 g wood powder immobilized with nitrifying bacterial
consortium  were 1.05, 3.98, 4.11, 4.2, 4.2,
4.3, 4.4, 4.62, 4.39, 4.98 mg/ L  respectively, whereas in the control it was
0.8 mg/ L. The NO2– N production in the same systems was
0.03, 0.98, 1.83, 2.08, 2.34, 2.01, 2.38, 2.18, 2.09, 2.99 respectively,
whereas in the control it was 0.098 mg/ L (Table.
3). TAN removal per day and quantity of immobilized NBC showed a
positive correlation (0.895).

Evaluation
of nitrifying potency of immobilized nitrifying bacterial consortia in a system
with low stocking density.

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now

            TAN removal was obvious from point of addition of NBC to the system nine
days after its initiation (Fig.3). After
two days, the entire TAN (4.99 mg/ L) was removed in the test tanks where average
lowering of 2.75 mg/ L/ day of TAN was observed. In the corresponding control a
lowering of 0.76 mg/ L/ day, three fold lower than the test tanks, was seen.  On the second day, the NO2–
N production in the test tank was 2.26 mg/ L and an increased out put of 3.9 mg/
L/ day on the third day. On subsequent days it declined, and by the time NO3-
– N production had commenced (on the 4th day onwards) with a corresponding
decrease of NO2– N (Fig. 4).
A negative correlation was observed between TAN and NO3- N in the
tests (r -0.59) indicating effective nitrification, whereas in the control
tanks elevated levels of NH4+ – N and NO2– N could be recorded.
TAN removal and drop in alkalinity (Fig.5)
in the test tanks were positively correlated (r = 0.838).

Evaluation
of nitrification potency of immobilized NBC in systems with high stocking
density.

            In the system with high stocking density, the entire
(9.98 mg/ L) quantity of total ammonia nitrogen in the test tanks could be removed
within five days (Fig.6). Average
lowering of 2.002 mg/ L/ day TAN was observed in the test tanks, whereas in the
corresponding control tanks it was 0.58 mg/ L/ day. In the tests NO2-
–N registered maximum value on the 14th day (3.35 mg/ L), which
declined corresponding to the decline of TAN concentration (Fig. 7). Mean
NO3- – N level increased from 0.1 to 6.39 mg/ L in
the test tanks, and remained at 0.005 to 1.89 mg/ L in the control
systems. NO3- – N levels were significantly higher (P