Understanding Mechanisms of Synergy between Acidification and Ultrasound Treatments for Activated Sludge Dewatering: From Bench to Pilot-Scale Investigation

Mei Qiang Cai, Jian Qiang Hu, George Wells, Youngwoo Seo, Richard Spinney, Shih Hsin Ho, Dionysios D. Dionysiou, Jie Su, Ruiyang Xiao*, Zongsu Wei

*Corresponding author for this work

Research output: Contribution to journalArticle

48 Scopus citations

Abstract

Enhancing activated sludge dewaterability is of scientific and engineering importance in the face of accelerated urbanization and stringent environmental regulations. In this study, we investigated the integration of acidification and ultrasound (A/US) treatment for improving sludge dewaterability at both bench- and pilot-scales. Our results showed that the A/US process exhibited significantly improved sludge dewatering performance, characterized by capillary suction time, cake moisture, and water/solid content of sludge cake. Synergistic dewatering mechanisms were elucidated with a suite of macro and spectroscopic evidence. Characterization of treated sludge revealed that US-induced thermal, mechanical shearing force, and radical oxidation effects disrupts floc cells and accelerates the decomposition of extracellular polymeric substances (EPS), releasing bound water into the bulk phase. In addition to enhancing hydrolysis of EPS, the acidic pH environment caused the protonation of functional groups on EPS, facilitating the reflocculation of US decomposed sludge for improved filterability. Our bench-scale and pilot-scale investigations provide a mechanistic basis for better understanding of the A/US process, and enable development of a viable and economical dewatering technology.

Original languageEnglish (US)
Pages (from-to)4313-4323
Number of pages11
JournalEnvironmental Science and Technology
Volume52
Issue number7
DOIs
StatePublished - Apr 3 2018

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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