Development Of Partial-Anammox Integreted Process And Its Nitrogen Removal Performance From The Simulated Sewage

Exploration of mainstream anammox process is research hotspot and challenges in the filed of municipal wastewater treatment all over the world.The influent characteristics of low ammonia and high C/N ratio are limited to achieve stably partial nitrification/anammox(PN/A).Therefore,the establishment of mainstream anammox process by means of other novel approaches has important practical significance.In this study,biofilm reactor was applied to start-up anammox and achieved within 40 d with treatment of low-strength ammonia and nitrite and feed of convenience activate sludge,the layered structure and contents of biocarrier in favor to create a suitable anammox growth microenvironment under anaerobic conditions.The multi-layer sequencing results showed that the relative abundance of An AOB increased with the depth of biological carrier.Subsequently,the impact of key operating parameters on the Anammox process was explored.Subsequently,the influence of key operating parameters on Anammox process was investigates.The nitrogen removal efficiency(NRE)of An SBBR-anammox system can reach to 95.3% through parameter optimization,and Candidatus Kuenenia was the dominant genus of An AOB.Furthermore,the tolerance performance of An SBBR-anammox system to C/N ratios was studied.It was found that NRE was affected slightly when C/N ratio was lower than 2,while NRE deteriorated rapidly when C/N ratio was higher than 3.In order to recover anammox,the An SBBR-anammox system only in 15 days when C/N ratio backed to 0.Microbial community analysis showed that the abundance of Anammox functional genera and genes(hzs and hdh)decreased significantly with the increase of C/N ratios.EPS secreted by biofilm benefited from the low C/N ratio environment,especially the proteins in TB-EPS played an important regulatory role in the activity recovery of Anammox.In order to simulate the real municipal sewage,the oxygenlimited SBBR-anammox system inoculated with anammox biofilm was used to treat the influent of 150 mg/L COD and 50 mg/L ammonia,and the nitrogen removal performance under seasonal temperature changes was investigated.The results indicated that the NRE of the system was above 70 % when the water temperature was above 18 °C,while decreased to about 40 % and high effluent of nitrate when it was below 15 °C.SBBR-anammox system could still enrich An AOB at low temperature.The effect of hydroxylamine addition on nitrogen removal under low temperature was further studied.It was found that the addition of a small amount of hydroxylamine(1–2 mg/L)could effectively promote partial nitrification and improve the performance of Anammox.The results of 3D-EEM analysis showed that the increase of EPS protein secretion at low temperature may be a resistance to adverse water temperature conditions,in which soluble microbial byproducts and tryptophan protein substances are the key.The dominant genus of An AOB changed from Candidatus Brocadia to Candidatus Kuenenia.The nitrogen removal was contributed of synergistic acitivity by different functional microorganisms(An AOB,AOB,NOB,DHB)under aeration environment.The results provide the necessary preliminary basis for the mainstreamanammox process of municipal sewage to establish based on heterotrophic/autotrophic coupling partial Anammox.