On August 5, 2015, while many people were enjoying boating and fishing on the scenic Animas River in New Mexico, the river was contaminated with 3 million gallons of yellow mining wastewater
(link to USA Today
article). It was accidentally released from an abandoned mine in Colorado by an Environmental Protection Agency (EPA) cleaning team, which took full responsibility. The wastewater
(link to wastewater community) contained high concentrations of arsenic, lead, cadmium and mercury. You can read about heavy metal toxicity in a previous blog post
. There may be other toxic heavy metals
(link to metal analysis community) as well.
Heavy metals in wastewater do not degrade and are persistent in our environment for a long time, and they must be measured and controlled. Here are some helpful resources about heavy metal analysis.
Webinars on ICP-MS and Heavy Metal Analysis
I wanted to let you know that on Oct. 1, 2015, Brian Walker, the analytical team leader at Sembcorp Utilities (UK) Limited
, (link to company’s website) will discuss the analysis of mercury and other heavy metals in wastewater using Inductively Coupled Plasma Mass Spectrometry
(ICP-MS) (link to product page). The webinar, titled Analysis of Trade Waste Effluent by ICP-MS
(link to registration page), is open for registration now. There’s also a webinar series
(link to registration site) on September 10 and 15 on ICP-MS method development and applications that promises to be informative.
How Wastewater Discharges Are Regulated
Wastewater discharge in the U.S. is strictly regulated under the Clean Water Act
(CWA) (link to EPA summary). The law only allows wastewater from municipal and industrial wastewater treatment systems to be discharged into navigable water with permits. Treated wastewater can be directly discharged to surface water (direct discharge) or first go through the Public Owned Treatment Works (POTW), often called wastewater treatment plant, before being discharged to surface water (indirect discharge). The direct discharge permits are regulated under the EPA’s National Pollutant Discharge Elimination System (NPDES)
. The EPA authorizes the majority of the states in the U.S. to administer the wastewater discharge permits under NPDES. Indirect discharge is regulated under the National Pretreatment Program
. For permits under both programs, strict industry effluent guidelines
(link to EPA effluent guidelines page) must be followed.
The direct discharge of wastewater from industrial sources relies on industrial wastewater treatment facilities to remove pollutants from produced wastewater. However, since the indirectly discharged wastewater is transported to POTW, it must be pretreated to remove large amounts of industry-specific contaminants before reaching POTW. This is to protect the POTW wastewater treatment facility from possible interference by industry-specific pollutants, or contaminant pass-through, as the common POTW is not designed to remove these contaminants.
The National Pretreatment Program uses pretreatment standards and limits
to regulate industrial users. The limits for toxic pollutants, including 12 heavy metals, are listed in the effluent guidelines and standards at 40 CFR 401.15.
Analytical Methods for Wastewater Testing
Different categories of CWA analytical methods
include approved methods as well as other EPA methods that are in draft or to be approved. The approved methods are categorized as: general-purpose, industry-specific, and Whole Effluent Toxicity (WET). General-purpose methods
, also called 304(h) or part 136 methods, are the methods used for measuring pollutants in matrices including wastewater, such as EPA method 200.5
, and 200.9
for general metal analysis and other methods for specific metals like mercury, platinum, and rhodium. Industry-specific methods
are used for specific industry and listed in Part 136 Table IF and IG, and in part 401 to 503. There are no elemental analysis methods in this category. WET methods
use organisms to test survival and reproduction changes upon application of the whole wastewater samples.
Mercury Analysis in Wastewater
Mercury is one of the most important contaminants analyzed in wastewater. Multiple methods have been developed for mercury analysis, but the methods used for the NPDES program must be approved under 40 CFR 136, as reviewed in the memo, Analytical Methods for Mercury in National Pollutant Discharge Elimination System (NPDES) Permits.
Although both EPA Methods 245.7 and 1631E use the same technology to measure mercury, the sensitivity of these two methods are ten-fold different. The difference between the two methods lies in the different digestion and separation methods
(link to presentation that compares the two methods). However, EPA Method 200.8 is also approved for mercury analysis as an alternate test procedure (ATP) method i...
What Ever Happened to the Animas River?
The contaminated river had been used for drinking water, irrigation and recreation, but was closed for public use. The Animas river was reopened for recreation on Friday August 14
after the contamination level was tested to be lower than what it would raise a health concern for recreational water. Additional Resources These are U.S. EPA methods and used mainly by U.S. testing labs. If you are testing contaminants in wastewater, I would like to hear your thoughts.