Accuracy of Rapid Tests Used for Analysis of Advanced Onsite Wastewater Treatment System Effluent
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Rapid tests provide an inexpensive, desirable alternative to standard laboratory analyses for testing advanced onsite wastewater treatment system (OWTS) effluent in the field. Despite their potential utility, their accuracy for analysis of effluent from advanced OWTS has not been assessed. We evaluated the accuracy of an initial suite of rapid tests commonly used to analyze wastewater (test strips for ammonium, pH, nitrate, and alkalinity; pH pocket meter; titration kit for dissolved oxygen (DO)) by comparing values obtained in the field to values obtained using standard laboratory methods. We tested final effluent from three different advanced nitrogen removal OWTS technologies sampled monthly for 7 months at 42 different sites within the greater Narragansett Bay watershed in Rhode Island, USA. Significant differences between values obtained using field and standard methods were found only for nitrate and pH test strips when the data were analyzed using ANOVA on ranks. However, regression analysis indicated that all test strip-based rapid methods and the DO titration kit produced values that deviated significantly from correspondence with standard analyses. When effluent samples were analyzed in the laboratory (to minimize sources of variability) using the same rapid tests, significant differences between rapid tests and standard analysis disappeared for all the tests. Evaluation of a suite of alternative rapid tests for ammonium, nitrate, pH, and alkalinity indicated that test kits for NH4 + and multi-analysis test strips for pH provide accurate results in the field. Our results indicate that the accuracy of rapid tests needs to be evaluated under field conditions before they are used to assess effluent from advanced N-removing OWTS.
KeywordsOnsite wastewater treatment system Rapid test Accuracy Wastewater Regression analysis
This project was funded by an agreement (CE96184201) awarded by the U. S. Environmental Protection Agency to the New England Interstate Water Pollution Control Commission in partnership with the Narragansett Bay Estuary Program, to J. A. Amador and G. W. Loomis. We thank the homeowners participating in our study for their willingness to allow us access to their systems. We thank our regulatory partners on this project, the Rhode Island Department of Environmental Management OWTS staff, for their technical support and assistance in locating systems for our study.
Although the information in this document has been funded wholly or in part by the United States Environmental Protection agency under agreement CE96184201 to NEIWPCC, it has not undergone the agency’s publications review process and therefore, may not necessarily reflect the views of the agency, and no official endorsement should be inferred. The viewpoints expressed here do not necessarily represent those of the Narragansett Bay Estuary Program, NEIWPCC, or USEPA, nor does mention of trade names, commercial products, or causes constitute endorsement or recommendation for use. Results discussed in this document are preliminary and have not been reviewed by NEIWPCC or NBEP.
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