Removal of high concentration ammonia from wastewater by a combination of partial nitrification and anammox treatment

Abstract

Attached growth reactors were developed separately for solids retention time (SRT)-controlled partial nitrification and for anaerobic ammonia oxidation (Anammox) treatment, and a new nitrogen removal process is proposed for wastewater containing highly concentrated ammonia. For partial nitrification, an attached growth medium of polyurethane foam was used. Partial nitrification was achieved stably under a SRT of 4 days, and the abundance ratio of NO-N to the sum of NH-N, NO-N and NO-N was approximately 0.8 after 10 days. Under a SRT of 4 days, the amoA gene concentrations of ammonia-oxidizing bacteria increased from 1×10⁸ to 7×10⁸ copies/l, whereas the 16S ribosomal RNA (16S rRNA) gene concentrations of nitrite-oxidizing bacteria did not increase. These results indicate that SRT-controlled operation is a promising technology for achieving partial nitrification. For the Anammox treatment, an attached growth medium of non-woven fabric was used. Inorganic nitrogen removal of approximately 80–90% was observed at an inorganic nitrogen loading rate of over 10 kgN/(m³-medium·d) and an influent nitrogen concentration of 400 mgN/l. Our non-woven fabric reactor showed similar or superior Anammox performance to that reported previously. By using a combination of these two rectors, we can develop a method that combines partial nitrification and Anammox treatment for effective and stable nitrogen removal.

Keywords:

• partial nitrification
• polyurethane foam
• solids retention time
• anaerobic ammonia oxidation
• non-woven fabric