Metagenomic Insights into the Effects of Seasonal Temperature Variation on the Activities of Activated Sludge

Abstract

It is well acknowledged that the activities of activated sludge (AS) are influenced by seasonal temperature variation. However, the underlying mechanisms remain largely unknown. Here, the activities of activated sludge under three simulated temperature variation trends were compared in lab-scale. The TN, HN3-H, and COD removal activities of activated sludge were improved as temperature elevated from 20 °C to 35 °C. While, the TN, HN3-H, COD and total phosphorus removal activities of activated sludge were inhibited as temperature declined from 20 °C to 5 °C. Both the extracellular polymer substances (EPS) composition (e.g., total amount, PS, PN and DNA) and sludge index of activated sludge were altered by simulated seasonal temperature variation. The variation of microbial community structures and the functional potentials of activated sludge were further explored by metagenomics. Proteobacteria, Actinobacteria, Acidobacteria and Bacteroidetes were the dominant phyla for each activated sludge sample under different temperatures. However, the predominant genera of activated sludge were significantly modulated by simulated temperature variation. The functional genes encoding enzymes for nitrogen metabolism in microorganisms were analyzed. The enzyme genes related to ammonification had the highest abundance despite the changing temperature, especially for gene encoding glutamine synthetase. With the temperature raising from 20 °C to 35 °C. The abundance of amoCAB genes encoding ammonia monooxygenase (EC:1.14.99.39) increased by 305.8%. Meanwhile, all the enzyme genes associate with denitrification were reduced. As the temperature declined from 20 °C to 5 °C, the abundance of enzyme genes related to nitrogen metabolism were raised except for carbamate kinase (EC:2.7.2.2), glutamate dehydrogenase (EC:1.4.1.3), glutamine synthetase (EC:6.3.1.2). Metagenomic data indicate that succession of the dominant genera in microbial community structure is, to some extent, beneficial to maintain the functional stability of activated sludge under the temperature variation within a certain temperature range. This study provides novel insights into the effects of seasonal temperature variation on the activities of activated sludge.

Effects of Bisphenol A Stress on Activated Sludge in Sequential Batch Reactors and Functional Recovery

“…However, under BPA stress, the abundances of these dominant genera decreased significantly, while different concentrations of BPA showed different population niches. Consistent with the research results of Ai et al, the dominant bacterial genera in artificial sewage domesticated sludge were Labilithrix and Ferribacterium [54].…”

“…In a study on autotrophic denitrification sludge, Curvibacter was found to be beneficial to improving the nitrate removal rate of sludge [63]. Acinetobacter and Comamonas play key roles in the removal of ammonia nitrogen and phosphorus under aniline stress [54]. Sphingobium is the dominant bacterial genus for the treatment of pharmaceutical wastewater in membrane bioreactors [64].…”

Whole Genome Sequencing and Comparative Genomic Analyses of Lysinibacillus pakistanensis LZH-9, a Halotolerant Strain with Excellent COD Removal Capability

“…In these experiments, the amount of each bottle of culture solution was 150 mL and the tests were done in triplicate. The method of optimization was referring to previous reports [26,27], and the concentrations of COD were measured by using potassium dichromate method [28]. LZH-9 culture solution was inoculated to LB medium.…”

Ethylmalonyl-CoA pathway involved in polyhydroxyvalerate synthesis in Candidatus Contendobacter

“…Gene abundance evaluation and species annotation were eventually performed. The method details were described in the previous studies (Ai et al 2019…”