Assessment of an Automated E. coli and Fecal Coliform Monitoring System by Comparison with Reference Methods Using the US-EPA ATP Protocol

Collaborative Efforts to Improve Environmental Monitoring (Session 2)
Oral Presentation

Prepared by R. Brown1, E. Marcotte2, D. Wilton2, C. Fricker3, L. O'Donnell1
1 - Queen's University, Dept. of Chemistry and School of Environmental Studies, 90 Bader Lane, Kingston, ON, K7L3N6, Canada
2 - TECTA-PDS Inc., 382 King St. West, Kingston, Ontario, K7K2Y2, Canada
3 - CFR Consulting, 118B Oxford Rd., Reading, Berkshire, RG17NG, United Kingdom


Contact Information: [email protected]; 613-533-2655

ABSTRACT

The US-EPA ATP protocol for wastewater and ambient water was used to develop a laboratory study to validate the E. coli (EC) and Fecal Coliform (FC) testing technology from TECTA-PDS by comparing with reference methods (US-EPA Method 1603, mTEC for EC; APHA Method 9222D, mFC, for FC). A well-established third-party laboratory was contracted to carry out the work. Final sewage samples were obtained from various locations in the continental USA and inoculated with filtered, primary sewage effluent to reach a target bacteria range (20-80 CFU/100 mL) suitable for the reference tests. Replicate 100 mL samples were analyzed in the TECTA system by adding to single-use test cartridges containing all required ingredients, while parallel samples were processed for the reference tests. Samples were confirmed using a multi-step procedure developed using the guidelines of the ATP protocol. Additional diluted samples were used to examine false negative rates. After some initial tests were run, minor modifications to the confirmation procedure were made to provide more straightforward results. The TECTA system provided rapid results with automated detection and reporting in 8 to 11 hours for all positive samples. A technician interpreted the reference tests after the prescribed 24 h period. The TECTA system provided quantitative results in agreement with the reference methods for both EC (51±35 vs 65±26 cfu/100 mL) and FC (53±37 vs 57±14 cfu/100 mL) parameters. The false positive rate (EC: 8.0%, FC: 0.0%) and false negative rate (EC: 0.0%, FC: 1.3%) were within an acceptable range. The ATP Protocol-based study method was effective for assessing the TECTA system performance.