Enhanced Sludge Dewaterability and Pathogen Inactivation by Synergistic Effects of Zero-Valent Iron and Ozonation

Jiangwei Yu, Keke Xiao, Jiakuan Yang*, Wenbo Yu, Kangyue Pei, Yuwei Zhu, Junxiong Wang, Sha Liang, Jingping Hu, Huijie Hou, Bingchuan Liu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

40 Scopus citations

Abstract

In this study, the efficiency of the combined zerovalent iron (ZVI) and ozone (O3) treatment at a pH of 2 (acid-ZVI-O3) for simultaneous improvement of sludge dewaterability and pathogen inactivation was investigated. The results showed that the ozone treatment alone deteriorated sludge dewaterability, while the introduction of acid-ZVI into the ozone treatment could significantly enhance the sludge dewaterability. At the optimal conditions with 30 mg O3 g-1 of total solid (TS) and 63 mg ZVI g-1 of TS at a pH of 2, the capillary suction time of conditioned sludge was 1.63 s L g-1 TS, which was much smaller than those of raw sludge (10.45 s L g-1 TS), the single ozonation treated sludge (16.07 s L g-1 TS), and the acid-ZVI-treated sludge (6.98 s L g-1 TS). The acid-ZVI-O3 treatment promoted the generation of hydroxyl radicals and showed synergistic effects in removing key hydrophilic substances which would deteriorate sludge dewaterability, i.e., humic acid-like compounds and soluble microbial byproduct-like substances in the tightly bound extracellular polymeric substances (TB-EPSs). Ferric iron was generated therein and worked as a coagulant to agglomerate sludge particles. The enhanced sludge dewaterability was further confirmed by a laboratory-scale diaphragm filter press. Moreover, the acid-ZVI-O3 treatment showed an effective inactivation of pathogens, which was below the limit specified for class A biosolids, according to the US EPA standard. As such, enhanced sludge dewaterability and pathogen inactivation can be simultaneously achieved with the acid-ZVI-O3 treatment.

Original languageEnglish
Pages (from-to)324-331
Number of pages8
JournalACS Sustainable Chemistry and Engineering
Volume7
Issue number1
DOIs
StatePublished - 7 Jan 2019
Externally publishedYes

Keywords

  • Acid-ZVI-O conditioning
  • Hydroxyl radicals
  • Pathogen inactivation
  • Sludge dewaterability
  • Waste activated sludge

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