Accuracy of Rapid Tests Used for Analysis of Advanced Onsite Wastewater Treatment System Effluent
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
- Bounds, T., Denn, G., & Bounds, N. T. (2004). Maintaining and troubleshooting advanced onsite systems: git’er done! 13th Technical Education Conference and Exposition, National Onsite Wastewater Recycling Association. Albuquerque.Google Scholar
- Fellers, T., Davidson, M., & Spring, K. (2015). Human vision and color perception. Molecular Expressions. Available at: http://micro.magnet.fsu.edu/primer/lightandcolor/humanvisionintro.html
- Heger, S. (2015). What’s your dissolved oxygen? . Onsite installer, Available at: http://www.onsiteinstaller.com/online_exclusives/2015/08/whats_your_dissolved_oxygen?utm_source=newsletter&utm_medium=email&utm_content=What%E2%80%99s%20Your%20Dissolved%20Oxygen%3F%20MORE&utm_campaign=150909_Installer
- Isbell, F., Mercer, D., & Iqbal, M. (2006). Reliability of water quality test strips for field measurement of nutrients essential for developing mosquito larvae. Am. J. Undergrad Res, 5(2), 1–8.Google Scholar
- Murphy, L., Cahn, M., & Smith, R. (2014). Accuracy of test strips for assessing nitrate concentration in soil and water. Salinas Valley Agriculture. Available at: http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=13140
- NSF International/US EPA. (2003). ETV protocol for verification of residential wastewater treatment—SeptiTech Model 400. Available at: http://archive.epa.gov/nrmrl/archive-etv/web/pdf/09_vs_septi.pdf.
- Ohio Environmental Protection Agency. (2010). Summary report of sample results obtained under the Household Sewage Treatment Systems General National Pollutant Discharge Elimination System Permit Program (Revised). Available at: https://www.odh.ohio.gov/~/media/ODH/ASSETS/Files/eh/STS/NPDES-2010-SampleRept.pdf.
- Post, F., Bryant, B., Batchily, K., Huete, R., Levine, J., Mays, D., & Escadafal, R. (1993). Correlations between field and laboratory measurements of soil color. Soil color, 35–49.Google Scholar
- Rhode Island Department of Environmental Management (RIDEM). (2013). Alternative or experimental onsite wastewater treatment system (OWTS) technologies. Available at: http://www.dem.ri.gov/programs/benviron/water/permits/isds/pdfs/ialist.pdf
- Russell, J. (1944). The colorimetric estimation of small amounts of ammonia by phenol: hypochlorite reaction. J. Biol. Chem, 156, 457–467.Google Scholar
- SeptiTech, Inc. (2009). Operation and maintenance manual septitech wastewater pretreatment system residential processor units M400/M550/M750. Lewiston: SeptiTech, Inc. ME. Available at: https://www.vdh.virginia.gov/EnvironmentalHealth/Onsite/documents/2009/Septitech,%20Inc/Section%204%20-%20SeptiTech%20OM%20Manual%20Residential%20Systems.pdf.Google Scholar
- Sweazy, J. (2009). The right kind of test. Water quality products, Available at: http://www.wqpmag.com/sites/default/files/rightkindoftest.pdf.
- United States Environmental Protection Agency (USEPA). (2007). Dissolved oxygen and biochemical oxygen demand. Available at: http://water.epa.gov/type/rsl/monitoring/vms52.cfm
- Webb, S. (2008). Colorimeter removes guesswork when testing pool water. Available at: http://aquamagazine.com/service/colorimeter-removes-guesswork-when-testing-pool-water.html