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

Table 1

Summary of performed experiments of nitrification and autotrophic denitrification processes [9, 12] for the evaluation of the production of N₂O, S⁰ and as intermediate compounds (subscript “i” indicates “influent” and subscript “e” indicates “effluent”).

Nitrification	pH	Temperature	-	-	-	-	DO tested		N2O-N production
		()	(mg/L)	(mg/L)	(mg/L)	(mg/L)	(mg/L)		(g N2O-N/g VSS·d)
Stage 1	7.5	23	500	124	170	170	0.5		10.6
Stage 2	7.5	23	500	124	170	170	1.0		18.7
Stage 3	7.5	23	500	124	170	170	2.0		13.8
Stage 4	7.5	23	500	124	170	170	5.0		12.4
Stage 5	7.5	23	500	122	90	236	0.5		2.3
Stage 6	7.5	23	500	122	90	236	1.0		9.8
Stage 7	7.5	23	500	122	90	236	2.0		7.5
Stage 8	7.5	23	500	122	90	236	5.0		6.6
Stage 9	7.5	23	500	9	3	451	0.5		1.2
Stage 10	7.5	23	500	9	3	451	1.0		4.0
Stage 11	7.5	23	500	9	3	451	2.0		1.8
Stage 12	7.5	23	500	9	3	451	5.0		0.0
Autotrophic denitrification	pH	Temperature							specific production	specific production
		()	(mg/L)	(mg/L)	(mg/L)	(mg/L)	(mg/L)	(mg/L)	(mg S^0/g VSS⋅d)	(mg -N/g VSS⋅d)
Stage 1	7.8	30	450	200	- -	- -	- -	- -	- -	- -
Stage 2	8.0	30	450	250	0.9	110	294	205	6.5	18.3
Stage 3	8.6	30	450	300	0.7	12	291	128	30.8	2.1
Stage 4	9.3	30	450	200	1.0	22	362	24	32.3	3.6
Stage 5	7.5	30	450	100	- -	- -	- -	- -	- -	- -
Stage 6	8.2	30	450	150	0.9	94	306	266	-13.0	15.7
Stage 7	8.4	30	450	300	1.0	13	309	160	24.0	2.1
Stage 8	7.7	30	450	350	0.9	77	239	375	-3.2	12.9
Stage 9	7.7	30	450	450	0.9	79	154	474	-3.3	13.2

Stable values were not achieved