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<p>Fast-growing amount of waste activated sludge (WAS) has awoken concerns on its environmental hazards and called forth appropriate treatment procedures. This study investigated low-strength ultrasound (25 kHz) effects on sludge for durations from 30 to 120 s. Results demonstrated that sludge oxidative status maximized to 54.34 × 10<sup>−6</sup>&#xa0;mol/L at 60&#xa0;s, whereas soluble chemical oxygen demand increased to 5438&#xa0;mg/L till 120 s, respectively. Three-dimensional excitation-emission matrix with quantitative analysis on dissolved organic matters of extracellular polymeric substances (EPS) revealed that fluorescence intensities of fulvic acid, soluble microbial metabolites (SoMM), and humic acid of soluble EPS increased at 60 s, and the counterparts of tyrosine and SoMM in loosely- and tight-bound EPS were enhanced from 60 to 120 s, which indicated the decrease of counterparts in WAS, therefore helping sludge dewaterability and reduction. Low-strength ultrasound increased sludge community diversities and shifted communities’ structures, and dominant genera, including <i>Methylotenera</i>, <i>Ferruginibacter</i>, Candidatus_<i>Competibacter</i>, <i>Saprospiraceae</i>, <i>Caldilineaceae</i>, and <i>Dokdonella</i>, were shared in common, whilst <i>Kapabacteriales</i>, <i>Nitrospira</i>, <i>Haliangium</i>, and <i>Macellibacteroides</i>, <i>Bacteroides</i>, <i>Arcobacter</i>, <i>Paludibacter</i>, <i>Trichococcus</i> varied due to sludge source differences. Functional prediction indicated no significant changes of dominant metabolic pathways or enzymes after ultrasonic treatment, meanwhile pathways and KOs correlating with organic matter metabolisms (e.g., ko00010, ko01200, and K00059) were enhanced. Phenotype prediction showed that ultrasound reduced relative abundances of “biofilm formation”, “oxidative stress tolerant”, “facultative anaerobic”, and “anaerobic”, however increased that of “aerobic”, and dominant genera contributing to phenotypic variations comprised <i>Methylotenera</i>, <i>Caldilineaceae</i>, <i>Dokdonella</i>, Candidatus_<i>Competibacter</i>, and <i>Saprospiraceae</i>, <i>Macellibacteroides</i>, <i>Trichococcus</i>, and <i>Paludibacter</i>.</p>

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Effects of Low-Strength Ultrasonic Treatment on Waste Activated Sludge Lysis and Shifts of Microbial Community Traits

  • 期刊论文

  • 发表日期：

    2025年12月11日

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  • Shugeng Feng,
  • Xinyun Zhang,
  • Wanlin Zeng,
  • Yaxuan Yang,
  • Tianhua Zhang,
  • Cuihong Zhou

摘要

Fast-growing amount of waste activated sludge (WAS) has awoken concerns on its environmental hazards and called forth appropriate treatment procedures. This study investigated low-strength ultrasound (25 kHz) effects on sludge for durations from 30 to 120 s. Results demonstrated that sludge oxidative status maximized to 54.34 × 10−6 mol/L at 60 s, whereas soluble chemical oxygen demand increased to 5438 mg/L till 120 s, respectively. Three-dimensional excitation-emission matrix with quantitative analysis on dissolved organic matters of extracellular polymeric substances (EPS) revealed that fluorescence intensities of fulvic acid, soluble microbial metabolites (SoMM), and humic acid of soluble EPS increased at 60 s, and the counterparts of tyrosine and SoMM in loosely- and tight-bound EPS were enhanced from 60 to 120 s, which indicated the decrease of counterparts in WAS, therefore helping sludge dewaterability and reduction. Low-strength ultrasound increased sludge community diversities and shifted communities’ structures, and dominant genera, including Methylotenera, Ferruginibacter, Candidatus_Competibacter, Saprospiraceae, Caldilineaceae, and Dokdonella, were shared in common, whilst Kapabacteriales, Nitrospira, Haliangium, and Macellibacteroides, Bacteroides, Arcobacter, Paludibacter, Trichococcus varied due to sludge source differences. Functional prediction indicated no significant changes of dominant metabolic pathways or enzymes after ultrasonic treatment, meanwhile pathways and KOs correlating with organic matter metabolisms (e.g., ko00010, ko01200, and K00059) were enhanced. Phenotype prediction showed that ultrasound reduced relative abundances of “biofilm formation”, “oxidative stress tolerant”, “facultative anaerobic”, and “anaerobic”, however increased that of “aerobic”, and dominant genera contributing to phenotypic variations comprised Methylotenera, Caldilineaceae, Dokdonella, Candidatus_Competibacter, and Saprospiraceae, Macellibacteroides, Trichococcus, and Paludibacter.