Sludge reduction by ozone: Insights and modeling of the dose-response effects

C Fall, B. C. Silva-Hernández, C. M. Hooijmans, C. M. Lopez-Vazquez, M. Esparza-Soto, M. Lucero-Chávez, M. C.M. van Loosdrecht

Research output: Contribution to journalArticleScientificpeer-review

22 Citations (Scopus)

Abstract

Applying ozone to the return flow in an activated sludge (AS) process is a way for reducing the residual solids production. To be able to extend the activated sludge models to the ozone-AS process, adequate prediction of the tri-atoms effects on the particulate COD fractions is needed. In this study, the biomass inactivation, COD mineralization, and solids dissolution were quantified in batch tests and dose-response models were developed as a function of the reacted ozone doses (ROD). Three kinds of model-sludge were used. S1 was a lab-cultivated synthetic sludge with two components (heterotrophs XH and XP). S2 was a digestate of S1 almost made by the endogenous residues, XP. S3 was from a municipal activated sludge plant. The specific ozone uptake rate (SO3UR, mgO3/gCOD.h) was determined as a tool for characterizing the reactivity of the sludges. SO3UR increased with the XH fraction and decreased with more XP. Biomass inactivation was exponential (e−β.ROD) as a function of the ROD doses. The percentage of solids reduction was predictable through a linear model (CMiner + Ysol ROD), with a fixed part due to mineralization (CMiner) and a variable part from the solubilization process. The parameters of the models, i.e. the inactivation and the dissolution yields (β, 0.008–0.029 (mgO3/mgCODini)−1 vs Ysol, 0.5–2.8 mg CODsol/mgO3) varied in magnitude, depending on the intensity of the scavenging reactions and potentially the compactness of the flocs for each sludge.

Original languageEnglish
Pages (from-to)103-112
Number of pages10
JournalJournal of Environmental Management
Volume206
DOIs
Publication statusPublished - 15 Jan 2018

Keywords

  • Activated sludge
  • COD fractions
  • Dose-response
  • Modeling
  • Ozonation
  • Sludge minimization

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