Dissimilatory iron reduction and odor indicator abatement by biofilm communities in swine manure microcosms

Hugo A. Castillo-Gonzalez, Mary Ann Bruns

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21 Scopus citations

Abstract

Animal waste odors arising from products of anaerobic microbial metabolism create community relations problems for livestock producers. We investigated a novel approach to swine waste odor reduction: the addition of FeCl3, a commonly used coagulant in municipal wastewater treatment, to stimulate degradation of odorous compounds by dissimilatory iron-reducing bacteria (DIRB). Two hypotheses were tested: (i) FeCl3 is an effective source of redox-active ferric iron (Fe3+) for dissimilatory reduction by bacteria indigenous to swine manure, and (ii) dissimilatory iron reduction results in significant degradation of odorous compounds within 7 days. Our results demonstrated that Fe3+ from FeCl3 was reduced biologically as well as chemically in laboratory microcosms prepared with prefiltered swine manure slurry and limestone gravel, which provided pH buffering and a substrate for microbial biofilm development. Addition of a 1-g liter-1 equivalent concentration of Fe3+ from FeCl 3, but not from presynthesized ferrihydrite, caused initial, rapid solids flocculation, chemical Fe3+ reduction, and Eh increase, followed by a 2-day lag period. Between 2 and 6 days of incubation, increases in Fe2+ concentrations were accompanied by significant reductions in concentrations of volatile fatty acids used as odor indicators. Increases in Fe2+ concentrations between 2 and 6 days did not occur in FeCl3-treated microcosms that were sterilized by gamma irradiation or amended with NaN3, a respiratory inhibitor. DNA sequences obtained from rRNA gene amplicons of bacterial communities in FeCl 3-treated microcosms were closely related to Desulfitobacterium spp., which are known representatives of DIRB. Use of iron respiration to abate wastewater odors warrants further investigation.

Original languageEnglish (US)
Pages (from-to)4972-4978
Number of pages7
JournalApplied and environmental microbiology
Volume71
Issue number9
DOIs
StatePublished - Sep 2005

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

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