Date of Graduation


Document Type


Degree Name

Bachelor of Science in Civil Engineering

Degree Level



Civil Engineering


Soerens, Thomas S.


Williams, Rodney D.

Second Reader

Zhang, Wen


This study sought to investigate the different response of two indicator species tests: Hach® PathoScreen™ Field Test and IDEXX Colilert® using the Quanti-Tray/2000® enumeration method. Both tests were carried out according to the instructions enclosed in the packages using diluted water samples taken from the secondary clarifier at the West Side Waste Water Treatment Plant in Fayetteville, AR. The tests were carried out at various temperatures in an attempt to reflect conditions that could be encountered in the field, where electricity, equipment, and expertise may not be available. The PathoScreen™ test responded adequately at a relatively wide range of temperatures, from approximately 22°C to 35°C, whereas the Quanti-Tray/2000® method was much more sensitive, producing erratic responses. In addition to PathoScreen™ yielding more consistent responses, the field kit and materials necessary for that test are much cheaper than those for using the Quanti- Tray/2000® method. These results suggest that the Hach® PathoScreen™ test, a hydrogen sulfide (H2S) presence-absence (PA) test, is more reliable for use in the field.