Combating Fecal Coliform Growth with a Diluted Chlorine Bleach Solution

Presenter Information

Steven Muir, Minnesota State University, MankatoFollow
Shaun Bulfer, Minnesota State University, Mankato
Cassandra Orcutt, Minnesota State University, Mankato
Maria Tiegs, Minnesota State University, Mankato
Ashley M. Veldkamp, Minnesota State University, Mankato

Location

CSU 253/4/5

Start Date

4-4-2011 1:30 PM

End Date

4-4-2011 3:00 PM

Student's Major

Mechanical and Civil Engineering

Student's College

Science, Engineering and Technology

Mentor's Name

Stephen Druschel

Mentor's Department

Mechanical and Civil Engineering

Mentor's College

Science, Engineering and Technology

Description

Escherichia coli bacteria resides in the lower intestines of warm and cold blooded animals, in which high levels in a lake environment show contamination by fecal material of some kind. The presence of this bacterium on a beach can cause infection of humans, as well as affect the environment, leading to the reduction of oxygen levels in lakes. For the past fifteen years the city of Bloomington, MN, has been dealing with high levels of fecal coliform at Bush Lake Beach which has led to beach closures. Recently, the city combated this bacterium by spraying the waterfront with a diluted chlorine bleach solution and collecting data on its impact. The purpose of this project was to replicate this approach in a lab setting to better understand the effectiveness of this type of treatment. Experimental units consisting of gutters with sand taken from Bush Lake Beach were constructed and inoculated with coliform bacteria, and sand samples were taken at subsequent times as well as before and after bleach treatments at 200 ppm for 60 minutes. Samples were assessed using the Most Probable Number Method, and data was compared with previous data, ultimately determining effectiveness of the treatment. Many strains of E. coli and other fecal coliforms are typically non-pathogenic to humans, but it is important to defer any pathogenic strains from occurring. By showing in a controlled environment that bleaching E. coli is successful, other cities can confidently use this treatment method.