TABLE 2.

Parameters for the kinetic model of the hydroxylamine disproportionation in the experiment shown in Fig. 5

Parameter	Description	Unit	Valuea
			Model A	Model B
k1	Rate constant of hydrazine formationb	mmol/g DW/h	0.25	0.29
k2	Rate constant of ammonificationb	mmol/g DW/h	0.30	0.31
k3A	Rate constant for hydrazine disproportionationb	mmol/g DW/h	0.024	n.a.d
k3B	Rate constant for reversed hydrazine formationb	mmol/g DW/h		0.080
K1,NH2OH	Half-saturation constant for hydroxylamine conversion with ammonium into hydrazineb	mM	0.0011	0.010
K2,N2H4	Half-saturation constant for hydrazine oxidation to N2b	mM	0.00063	0.00050
K2,NH2OH	Half-saturation constant for hydroxylamine reduction to ammoniumb	mM	0.14	0.20
K3A,N2H4	Half-saturation constant for hydrazineb	mM	0.044	n.a.
K3B,N2H4	Half-saturation constant for hydrazineb	mM	n.a.	0.0061
Cx	Biomass concnc	g DW/liter	7.8	7.8
C0,N2H4	Initial hydrazine concnc	mM	0.0001	0.0001
C0,NH4	Initial ammonium concnc	mM	2.0	2.0
C0,NH2OH	Initial hydroxylamine concnc	mM	4.1	4.1

^aModel A involved a separate hydrazine disproportionation reaction, whereas with model B, the hydrazine formation reaction was considered to be reversible. The two reaction schemes are presented in Fig. 4.

^bParameters were fitted to the measured nitrogen species concentrations.

^cInitial conditions were based on measured values.

^dn.a., not applicable.