Evaluation of N2O Production from Anaerobic Ammonium Oxidation (Anammox) at Different Influent Ammonia to Nitrite Ratios

Nitrogen discharged to aquatic system can effect in eutrophication. The improper treatment design to remove nitrogen could also cause negative effect to atmospheric environment by emission of nitrous oxide (N2O). The conventional biological denitrification process under the condition of a low influent COD/N ratio or electron donor to electron acceptor ratio, N2O could be detected. However, recently, autotrophic denitrificaiton process named ANAMMOX has been applied for nitrogen removal from wastewater containing high NH4+ but low carbon content, for example the anaerobically treated swine wastewater in which carbon content was only half of that recommended for conventional biological nitrogen removal process. Anammox bacteria were able to use ammonia as electron donor and nitrite as electron acceptor under anaerobic condition. This study investigated the N2O production by Anammox process operated in SBR reactors with HRT of 4 days by varying influent ammonia to nitrite ratios or electron donor to electron acceptor ratios at 0.75:1, and 1:1. The results showed that the substrate consumption mole ratios (ΔNO2-N/ΔNH4-N) at the influent ratio of 0.75:1 and 1:1were 2.2:1 and 1.7:1, respectively. Moreover the average N2O of 1.05 ppm was detected even at the higher influent ratio of 1:1.