Nitrogen removal strategy for real swine wastewater by combining partial nitrification-denitrification process with anammox

Abstract

Anammox process offers reduced operational cost and energy requirement compared to nitrification-denitrification methods due to lower biomass generation and no need for external carbon sources and aeration. High ammonia concetration and low biodegradable anaerobic digester of swaine wastewater provided an advantage for the growth of anammox microorangism. An anoxic/oxic (A/O) SBR and an anammox SBR were implemented parallelly to treat the same swine wastewater with partial nitrification/denitrification and partial nitrification/anammox process, respectively, and to compare their nitrogen removal efficiency. The nitrogen removal rates (NRRs) of the A/O SBR and anammox SBR were 0.054 and 0.26 kg-N/m³/day, respectively. The lower NRR of the A/O SBR could be attributed to insufficient biodegradable organic carbon sources in the denitrification process. The kinetic parameters obtained from the two SBRs were applied to estimate the time required for using the A/O process and partial nitrification/anammox process to treat the same amount of ammonia with the same reaction volume. Results showed that the A/O process required 3.3 times the reaction time of the partial nitrification/anammox process, suggesting that the partial nitrification/anammox process is a more efficient and economic nitrogen removal process for swine wastewater treatment. The next generation sequencing results revealed that Candidatus Brocadia, ranging from 10 to 23%, was the predominant anammox bacteria in the anammox SBR. More than 78.2 % of nitrite in the anammox SBR was removed through the anammox reaction.

Keywords: Anaerobic digester; Anammox; Candidatus brocadia; Next generation sequencing; Quantitative polymerase chain reaction; Sequencing batch reactors.