Indicator Organisms in Wastewater Treatment Wetlands

Jepson Sutton

SWES 574

10-31-02

Indicator Organisms

• The detection of pathogenic organisms is a time-consuming, labor-intensive task, requiring highly trained technicians

• For this reason, scientist have identified certain organisms that, when detected, are a definitive indication of fecal contamination.

Indicator Organisms

• Indicator organisms are considered normal flora (always present) in the digestive system of all warm-blooded animals, including humans.

• The detection of indicator organisms suggests that enteric pathogenic microorganisms may also be present due to the fecal contamination.

Characteristics of an effective Indicator

• It is normal flora of warm-blooded animals • It is present when pathogens are present,

and undetected in uncontaminated samples • The indicator should be found in greater

concentrations than pathogens. • It should have a similar resistance to

environmental stress and water treatment processes as the pathogen.

Characteristics of an effective Indicator

• It must require a host for replication. (eliminates replication in the environment)

• Rapid, easy, and inexpensive detection methods

• Nonpathogenic

Types of indicator organisms

• Total coliforms – First group of indicators developed– Problematic because of the ability of some species to

replicate in the environment

• Fecal coliforms – Subgroup of Total coliforms– Restricted to fecal origins

• Fecal Streptococci – Primarily an indication of animal fecal pollution– FC/FS ratio

Types of indicator organisms

• Anaerobic bacteria – Clostridium: spore forming bacteria /

environmental resistance– Bacteroides: limited environmental resistance

• Bacteriophage – Viruses that require certain bacterial hosts for

replication– Indication of both bacterial and viral

contamination.