Predicting Accumulation of Intermediate Compounds in Nitrification and Autotrophic Denitrification Processes: A Chemical Approach

Table 2

Reactions involved during ammonia oxidation and autotrophic denitrification processes, number of e^- transferred and ∆G (kJ) for each reaction.

Process		Reaction	e^-	∆G (kJ)
Partial nitrification
	(i)	+ 3/2 O2 → + 2 H^+ + H2O	6
	(ii)	2 + 2 O2 → N2O + 2 H^+ + 3 H2O	8
Autotrophic denitrification
	(iii)	5 HS^- + 2 + 7 H^+ → 5 S + N2 + 6 H2O	10
	(iv)	5 HS^- + 8 + 3 H^+ → 5 + 4 N2 + 4 H2O	40
	(v)	HS^- + + H^+→ S + + H2O	2
	(vi)	HS^- + 4 → + H^+ + 4	8
	(vii)	5 S + 6 + 2 H2O → 5 + 4 H^+ + 3 N2	30
	(viii)	S + 3 + H2O → + 2 H^+ + 3	6

R is the ideal gas constant (8.31·10⁻³ kJ/mol·K); T is the operational temperature (K); concentrations are given as molar (M).