Modeling the pH-mediated extraction of ionizable organic contaminants to improve the quality of municipal sewage sludge destined for land application

Arjun K. Venkatesan, Rolf Halden

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

A model was developed to assess the impact of adding acids and bases to processed municipal sewage sludge (MSS) to mobilize contaminants, facilitating their removal from sludge by flushing prior to land application. Among 312 organic contaminants documented to occur in U.S. MSS, 71 or 23% were identified as ionizable organic contaminants (IOCs), contributing a disproportionately large fraction of 82% of the total mass of sludge-borne contaminants. Detected IOCs included 57 pharmaceuticals and personal care products, 12 perfluorinated compounds, one surfactant and one pesticide. Annually, about 2000 t of IOCs were estimated to be released to U.S. soils via land-application of MSS. A partitioning model developed to assess the impact of pH on hydrophobic sorption revealed that between 36 and 85% of the mass of individual classes of IOCs potentially could be desorbed from MSS via pH adjustment and flushing. Thus, modeling results suggest that a sequential pH treatment [acidic (~ pH 2) followed by basic (~pH 12) treatment] has the potential to reduce the burden of harmful IOCs in MSS applied on U.S. land by up to 40 ± 16 t annually. This approach may serve as a cost-effective treatment process that can be implemented easily in existing sludge treatment infrastructure in the U.S. and worldwide, serving to significantly improve the quality of MSS destined for land application.

Original languageEnglish (US)
Pages (from-to)736-741
Number of pages6
JournalScience of the Total Environment
Volume550
DOIs
StatePublished - Apr 15 2016

Keywords

  • Biosolids
  • Ionizable compounds
  • Partitioning model
  • Sewage sludge
  • Sludge treatment

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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