User-Based Photometer Analysis of Effluent from Advanced Nitrogen-Removal Onsite Wastewater Treatment Systems
Advanced nitrogen-removal onsite wastewater treatment systems (OWTS) are used to reduce total nitrogen (N) levels in domestic wastewater. Maintaining system performance requires regular monitoring and in situ rapid tests can provide an inexpensive option for assessing treatment performance. We used a portable photometer to measure ammonium and nitrate concentrations in final effluent from 46 advanced N-removal OWTS, sampling each site at least three times in 2017. To assess photometer accuracy, we compared measurements made using the photometer with those determined by standard laboratory methods using linear regression analysis and a two-tailed t test to compare regression parameters to those for a perfect linear relationship (slope = 1, intercept = 0). Our results show that photometer-based analysis reliably estimates inorganic N (ammonium and nitrate) concentration in field and laboratory settings. Photometer-based analysis of the sum of inorganic N species also consistently approximated the total N concentration in the final effluent from the systems. A cost-benefit analysis indicated that the photometer is a more cost-effective option than having samples analyzed by commercial environmental testing laboratories after analysis of 8 to 33 samples. A portable photometer can be used to provide reliable, cost-effective measurements of ammonium and nitrate concentrations, and estimates of total N levels in advanced N-removal OWTS effluent. This method can be a viable tool for triaging system performance in the field, helping to identify systems that are not functioning properly and may need to be adjusted or repaired by an operation and maintenance service provider in order to meet treatment standards.
KeywordsOnsite wastewater treatment system Wastewater Rapid test Photometer Nitrogen Regression analysis
We thank our regulatory partners at the Rhode Island Department of Environmental Management and the town of Charlestown, RI, for assisting us with technical aspects of the project, as well as procuring study sites. We also thank the Charlestown homeowners who allowed us to study their advanced N-removal OWTS. Special thanks go to Matt Dowling, Alicia Boucher, and Jonathan Ludovico for their technical and field support, and to Andrew Ross for assistance with the development of a cost-benefit analysis.
Although the information in this paper has been funded wholly or in part by the U.S. Environmental Protection Agency, it has not undergone the agency’s publications review process and therefore may not necessarily reflect the views of the agency; no official endorsement should be inferred.
This work was funded by the USDA National Institute of Food and Agriculture and Hatch Multi-State NE 1545 Project (accession number 1007770) and by a grant (00A000128-0) awarded by the U. S. Environmental Protection Agency to Jose Amador and George Loomis at the University of Rhode Island.
Compliance with Ethical Standards
The viewpoints expressed here do not necessarily represent those of the town of Charlestown, the Rhode Island Department of Environmental Management, or the U. S. Environmental Protection Agency, nor does mention of trade names, commercial products, or causes constitute endorsement or recommendation for use.
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