Molecular characterization of the microbial community in onsite treatment units

J. Tomaras, J. W. Sahl, J. R. Spear, R. L. Siegrist

Research output: Contribution to conferencePaperpeer-review

1 Scopus citations


Little is currently known about the microbiological processes and interactions occurring within an onsite wastewater system (OWS). Traditional methods for detecting microorganisms in wastewater have been restricted to culturing techniques. During the last decade, however, molecular techniques have enabled researchers to examine microbial diversity using culture-independent techniques. A program of research at the Colorado School of Mines focused on quantifying and interpreting microbial diversity was employed for examining OWS. The goal of this work was to identify and characterize the microbial community inhabiting septic tank effluent. Samples were collected from a traditional septic tank as well from two septic tanks outfitted with aerobic bacterial generator treatment units (ABG). Microbial community characterization was performed via 16S rRNA gene sequence analysis and revealed little difference in composition between systems. The wastewater environments were primarily dominated by two Phyla, Proteobacteria and Bacteroidetes and the genus Arcobacter (Campylobacteraceae family). Other Phyla represented in low numbers included Firmicute. The Phyla diversity found in wastewater was similar to what has been reported for the human intestine, but is a sharp contrast to diverse environments (e.g. soils). Previously published research indicates that the 1014 total bacteria present in the human intestine are primarily dominated by members of Firmicutes and Bacteroidetes, but also include less abundant Phyla such as Actinobacteria and Proteobacteria. Preliminary results suggest that a significant community change occurs between the gut and the onsite system. From an ecological engineering point of view, understanding this community shift could allow improved system design as well as permit innovative developments.

Original languageEnglish (US)
StatePublished - 2007
Externally publishedYes
Event11th National Symposium on Individual and Small Community Sewage Systems - Warwick, RI, United States
Duration: Oct 20 2007Oct 24 2007


Conference11th National Symposium on Individual and Small Community Sewage Systems
Country/TerritoryUnited States
CityWarwick, RI


  • 16SrRNA
  • Microbes
  • Septic tank effluent

ASJC Scopus subject areas

  • Bioengineering
  • Agronomy and Crop Science
  • Waste Management and Disposal


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