12
K. Ramani et al.
create anoxic environment required for the anammox process. Canon process has
been performed on laboratory scale. The volumetric loading rate of the canon process
(1.5 kg N m
−3 day
−1 in a gas—lift reactor) is lower than anammox process [47].
However, the economics of the canon process might be advantageous because of
the use of only one reactor. Canon process has not been tested on full scale, but
it is known to occur in nitrification system and convert ammonium to nitrate and
dinitrogen gas [48–50].
NH 4
+
+ 1.5O 2 → NO 2
−
+ 2H
+
+ H 2 O
G
◦◦
− 275 KJ mol
−1
(1)
NH 4
+
+ NO 2
−
→ N 2 + 2H 2 O
G
◦◦
− 357 KJ mol
−1
(2)
2.3.4 NO x Process
The addition of nitrogen oxides to the wastewater offers the new opportunity in
the wastewater treatment by stimulating and controlling the denitrification activity
of the nitrosomonas-like microorganisms. Addition of nitrogen oxide simulate the
nitrosomonas-like microorganisms to nitrify and denitrify simultaneously under oxic
condition with dinitrogen as the main product (Fig. 1). Equations (1)–(3) shows the
nitrogen conversion in a subsequent nitrification and denitrification process without
NO x supply and Eqs. (6)–(8) shows the conversion of nitrogen which is influenced
by NO x supply. The [H] indicate reducing equivalents.
NO x (NO/NO 2 ) acts as an inducers by inducing denitrification activity of the
ammonia oxidizers. It is added in a trace amounts to the wastewater (NH 4
+ /NO 2
ratio about 1000/1–5000/1) [51]. As a result 50% of the [H] (reducing equivalents)
are transferred to nitrite (terminal electron acceptor) (Eq. 6) instead of oxygen, which
results in the reduction in the oxygen consumption of the process. (Eqs. 6 and 8).
Nitrification
3NH 4
+
+ 6O 2 → 3NO 3
−
+ 6H
+
+ 3H 2 O
( 3 )
Denitrification
3NO 3
−
+ 3H
+
+ 15[H] → 1.5N 2 + 9H 2 O
( 4 )
Sum
3NH 4
+
+ 6O 2 + 15[H] → 1.5N 2 + 12H 2 O + 3H
+
(5)
K. Ramani et al.
create anoxic environment required for the anammox process. Canon process has
been performed on laboratory scale. The volumetric loading rate of the canon process
(1.5 kg N m
−3 day
−1 in a gas—lift reactor) is lower than anammox process [47].
However, the economics of the canon process might be advantageous because of
the use of only one reactor. Canon process has not been tested on full scale, but
it is known to occur in nitrification system and convert ammonium to nitrate and
dinitrogen gas [48–50].
NH 4
+
+ 1.5O 2 → NO 2
−
+ 2H
+
+ H 2 O
G
◦◦
− 275 KJ mol
−1
(1)
NH 4
+
+ NO 2
−
→ N 2 + 2H 2 O
G
◦◦
− 357 KJ mol
−1
(2)
2.3.4 NO x Process
The addition of nitrogen oxides to the wastewater offers the new opportunity in
the wastewater treatment by stimulating and controlling the denitrification activity
of the nitrosomonas-like microorganisms. Addition of nitrogen oxide simulate the
nitrosomonas-like microorganisms to nitrify and denitrify simultaneously under oxic
condition with dinitrogen as the main product (Fig. 1). Equations (1)–(3) shows the
nitrogen conversion in a subsequent nitrification and denitrification process without
NO x supply and Eqs. (6)–(8) shows the conversion of nitrogen which is influenced
by NO x supply. The [H] indicate reducing equivalents.
NO x (NO/NO 2 ) acts as an inducers by inducing denitrification activity of the
ammonia oxidizers. It is added in a trace amounts to the wastewater (NH 4
+ /NO 2
ratio about 1000/1–5000/1) [51]. As a result 50% of the [H] (reducing equivalents)
are transferred to nitrite (terminal electron acceptor) (Eq. 6) instead of oxygen, which
results in the reduction in the oxygen consumption of the process. (Eqs. 6 and 8).
Nitrification
3NH 4
+
+ 6O 2 → 3NO 3
−
+ 6H
+
+ 3H 2 O
( 3 )
Denitrification
3NO 3
−
+ 3H
+
+ 15[H] → 1.5N 2 + 9H 2 O
( 4 )
Sum
3NH 4
+
+ 6O 2 + 15[H] → 1.5N 2 + 12H 2 O + 3H
+
(5)