Effect of Free Ammonia, Free Nitrous Acid, and Alkalinity on the Partial Nitrification of Pretreated Pig Slurry, Using an Alternating Oxic/Anoxic SBR

Table 1

Characterization of the different operational stages of the SBR reactor.

Parameter	Unit	Stage
		I		II		III
		Influent	Effluent	Influent	Effluent	Influent	Effluent
Operation time	d	0–75		76–190		191–270
ALRs	g -N/L⋅d	0.06		0.09		0.15
Total alkalinity/-N	g/g		—		—		—
pH
	mg/L
-N	mg/L
-N	mg/L	<1.0		<1.0		<1.0
-N	mg/L	<1.0		<1.0		<1.0
-N/-N	g/g	—		—		—	<0.1 ± <0.1
NIT	%
NAR	%					1 ± <0.1
	%
	%
	g/g

bicarbonate (NaHCO₃) was added to the influent to keep it at total alkalinity/-N ratio of 4.1 g/g. the stable period (days 76 to 160).