Contaminant removal by wastewater treatment plants in the Stillaguamish River Basin, Washington

Fact Sheet 2015-3023
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Human activities in most areas of the developed world typically release nutrients, pharmaceuticals, personal care products, pesticides, and other contaminants into the environment, many of which reach freshwater ecosystems. In urbanized areas, wastewater treatment plants (WWTPs) are critical facilities for collecting and reducing the amounts of wastewater contaminants (WWCs) that ultimately discharge to rivers, coastal areas, and groundwater. Most WWTPs use multiple methods to remove contaminants from wastewater. These include physical methods to remove solid materials (primary treatment), biological and chemical methods to remove most organic matter (secondary treatment), advanced methods to reduce the concentrations of various contaminants such as nitrogen, phosphorus and (or) synthetic organic compounds (tertiary treatment), and disinfection prior to discharge (Metcalf and Eddy, Inc., 1979). This study examined the extent to which 114 organic WWCs were removed by each of three WWTPs, prior to discharge to freshwater and marine ecosystems, in a rapidly developing area in northwestern Washington State. Removal percentages for each WWC were estimated by comparing the concentrations measured in the WWTP influents with those measured in the effluents. The investigation was carried out in the 700-mi2Stillaguamish River Basin, the fifth largest watershed that discharges to Puget Sound (fig. 1).

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Contaminant removal by wastewater treatment plants in the Stillaguamish River Basin, Washington
Series title Fact Sheet
Series number 2015-3023
DOI 10.3133/fs20153023
Year Published 2015
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Washington Water Science Center
Description 4 p.
Country United States
State Washington
Other Geospatial Stillaguamish River Basin
Datum North American Datum of 1983
Projection Transverse Mercator projection, UTM Zone 10
Online Only (Y/N) Y
Additional Online Files (Y/N) N
Google Analytic Metrics Metrics page
Additional publication details