Low C/N Promotes Stable Partial Nitrification by Creating Spatial and Nutrient Niches for Microbial Community in Treating High-Strength Ammonium Landfill Leachate
36 Pages Posted: 20 Oct 2022
Abstract
Partial nitrification is the crucial step for treating high-strength ammonium landfill leachate with low C/N ratio, as it can be associated with anammox and denitrification processes to removal nitrogen totally with less carbon addition. However, high ammonia loading often causes the instability of partial nitrification process. Less carbon addition can promote the stability of partial nitrification and increase the nitrite accumulation ratio (NAR). Nevertheless, the microbial mechanisms within remain further elusive. In this study, two laboratory-scale sequencing batch reactors were constructed and operated for 125 days, which were fed with ammonia synthetic wastewater with C/N of 0.6 (CN system) and C/N of 0.0 as the control (N system). CN system performed more stably and had the highest NAR of 100%. EPS generated from carbon source provided spatial and nutrient niches to tighten the cooperation of functional microorganisms, thus, enhanced the stability and efficiency of partial nitrification. Thauera was the dominant denitrifier in CN system. Nitrosomonas was one of the most important autotrophic ammonia oxidizing bacteria, while Paracoccus and Flavobacterium were the main heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria in CN system. The enrichment of HN-AD bacteria outcompeted nitrite oxidizing bacteria (NOB), therefore leaded to higher nitrite accumulation in CN system.
Keywords: sequencing batch reactor, Extracellular polymeric substances, Heterotrophic nitrification-aerobic denitrification, Partial nitrification, microbial community structure
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