Partial Nitritation of Swine Wastewater in View of Its Coupling with the Anammox Process

Partial nitritation (PN) of swine wastewater was investigated in a sequencing batch reactor (SBR) using a high‐performance nitrifying sludge. Characteristics of the wastewater used were low content of biodegradable organic matter and a high alkalinity‐to‐ammonium ratio. The target oxidation of ammonium nitrogen (NH 4 + –N) to nitrite nitrogen (NO 2 − –N) was 57% (1.32 g NO 2 − –N g – 1 NH 4 + –N), which corresponds with the reaction ratio of the anaerobic ammonium oxidation (anammox). This target was successfully achieved at 32°C by controlling the inflow rate and the corresponding nitrogen loading rate (NLR). An average NLR of 1.47 g NH 4 + –N L −1 d −1 was applied to the partial nitritation sequencing batch reactor during a period of 70 d. The nitrite production rate obtained was 0.91 g NO 2 − –N L −1 d −1 . No nitrate was produced. The PN effluent contained 1.38 g NO 2 − –N g −1 NH 4 + –N, which was within 5% of the target ratio. Under steady composition of the wastewater, the pH was shown to be a good indicator of the PN process performance. Furthermore, in a second sequencing batch reactor, the anaerobic ammonium oxidation process was effectively applied to the PN effluent, attaining a nitrogen conversion rate of 0.36 g N L −1 d −1 (14.3 mg N g −1 volatile suspended solids h −1 ).