Table 1.

The NH₃ and NO₂⁻ accumulation under different hydraulic retention time (HRT).

Reactor	HRT	Influent (mg/L)		Effluent (mg/L)
		NH3	NO2−	NH3	NO2−
CW II	2	0.4 ± 0.2	0.01 ± 0.01	0.1 ± 0.1	0.06 ± 0.02
	3	0.5 ± 0.2	0.01 ± 0.01	0.2 ± 0.1	0.86 ± 0.4
	4	0.4 ± 0.2	0.01 ± 0.01	0.1 ± 0.1	0.04 ± 0.02
CW I	2	0.4 ± 0.2	0.01 ± 0.01	0.3 ± 0.1	0.17 ± 0.02
	3	0.5 ± 0.2	0.01 ± 0.01	1.0 ± 0.3	1.99 ± 0.5
	4	0.4 ± 0.2	0.01 ± 0.01	0.8 ± 0.3	0.69 ± 0.3