Composition and Dynamics of the Activated Sludge Microbiome during Seasonal Nitrification Failure

Abstract

Wastewater treatment plants in temperate climate zones frequently undergo seasonal nitrification failure in the winter month yet maintain removal efficiency for other contaminants. We tested the hypothesis that nitrification failure can be correlated to shifts in the nitrifying microbial community. We monitored three parallel, full-scale sequencing batch reactors over the course of a year with respect to reactor performance, microbial community composition via 16S rRNA gene amplicon sequencing, and functional gene abundance using qPCR. All reactors demonstrated similar changes to their core microbiome, and only subtle variations among seasonal and transient taxa. We observed a decrease in species richness during the winter, with a slow recovery of the activated sludge community during spring. Despite the change in nitrification performance, ammonia monooxygenase gene abundances remained constant throughout the year, as did the relative sequence abundance of Nitrosomonadacae. This suggests that nitrification failure at colder temperatures might result from different reaction kinetics of nitrifying taxa, or that other organisms with strong seasonal shifts in population abundance, e.g. an uncultured lineage of Saprospiraceae, affect plant performance in the winter. This research is a comprehensive analysis of the seasonal microbial community dynamics in triplicate full-scale sequencing batch reactors and ultimately strengthens our basic understanding of the microbial ecology of activated sludge communities by revealing seasonal succession patterns of individual taxa that correlate with nutrient removal efficiency.

Investigating Industrial Effluent Impact on Municipal Wastewater Treatment Plant in Vaal, South Africa

“…A similar pattern was also noted during each of the other seasons (Table 1). However, no significant difference in temperatures was observed for the different sites (ANOVA, p = 0.879), consistent with the findings that temperature of wastewater generally mirrors the local prevailing ambient conditions [14,24,25]. According to Mahgoub et al [26], a rise in the WWTP influent temperature above 35 • C is associated with negative effects on biological activity during the treatment process, that may reduce the waste treatment efficiency.…”

Influence of short- and long-term exposure on the biodegradation capacity of activated sludge microbial communities in ready biodegradability tests

“…6). This observation is consistent with the literature, as a lower diversity in winter has already been reported, 33 without clear influence on the community activity. This is the case in the present investigation, in which the divergence of diversity and composition of the inocula did not have any effect on the degradation pattern of the test substances, in the standard RBT ( Fig.…”

Critical evaluation of short, long, and hybrid assembly for contextual analysis of antibiotic resistance genes in complex environmental metagenomes

“…However, such hybrid assembly approaches have not been critically evaluated in the context of complex environmental samples. Environmental samples are especially challenging for metagenome assembly due to the presence of tens of thousands of microbial species (e.g., Johnston et al 33 ), including many closely-related strains 34 and low abundance species with similar depth profiles that are difficult to distinguish 35 , 36 .…”