 Lab Matters is a series of technical articles from Environmental Express that are intended to aid in the comprehension of the common analyses in the environmental laboratory. They will all have the same basic format that you see here; an introduction section that will give some basics about the parameter and test method, and approved method listing for a listing of analytical methods to choose from, a method summary that gives a brief outline of what the method does, and a section with important things to know. Finally, each Lab Matters guide will contain a simplified step by step method on how to perform the analysis. This will help you get the sequence of your analysis right as well as give guidance on products you can use to simplify the process.
Click here to download the full Lab Matters Introduction
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Friday, 03 May 2013 11:23 |
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Introduction - BOD, like COD, is not one definable particle. You cannot count BOD molecules. BOD is the amount of oxygen consumed by decomposition of the sample during the incubation period. The intent is to measure what affect the sample will have on oxygen available to living organisms in the waters into which the waste is discharged. If the BOD of a waste is high enough, the microbial population will quickly deoxygenate the water and render it unsuitable for other forms of marine life. This can cause dead zones in a river or other body of water. There is
an additional subset of BOD that is required in certain areas. This is referred to as carbonaceous BOD or CBOD. This measures along the same basic principle as BOD, except that an inhibitor is added to exclude the oxygen consumption by nitrogen fixing bacteria. Sometimes BOD will be referred to as BOD5 or five day BOD. |
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Tuesday, 30 April 2013 15:31 |
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Introduction – Water has the ability to dissolve a large variety of materials.
Approved Methods – – There are three different approved methods; all of which follow a similar analysis
procedure. The notable differences are slight variations in requirements for the supplies used.
• SM2540 C – 1997
• ASTM D5907-03
• USGS I-1750-85
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Friday, 25 January 2013 08:39 |
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Introduction – The presence of certain bacteria are often a good indicator of water quality. Members of the coliform group serve as an indicator of pollutant vectors in the water system, specifically gaps in sanitary treatments. Coliform bacteria are quite common in the environment and most of them, by themselves, are not threats to the public health. The EPA recently revised the total coliform rule to eliminate public notification requirements based only on the presence of total coliforms. It is the detection of coliform bacteria associated with fecal material that is a true cause for concern.
Approved Methods – There are two different approved methodologies to test for bacteria. These are most probable number (MPN) and membrane filtration (MF). The MPN procedure can be further broken down into traditional multiple tube methods, which generally rely on physical indicators of gas production and chemical indicators of acid production by the growing bacteria and multiple well methods, which are also referred to as defined enzyme substrate tests. The approved methods are broken down as follows:
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Thursday, 29 November 2012 14:58 |
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Introduction – Phosphorous is a very important element when it comes to life on earth. In most fresh water systems it is the limiting nutrient for overall growth. Many wastewater treatment plants actually add phosphorous into their process stream to optimize the biological treatment. For this reason, phosphorous is regulated as a pollutant not because it is detrimental to life but because it can cause overgrowth of certain plant life that will upset the balance in an aquatic habitat. This is a case where too much of a good thing can be harmful.
Approved Methods – There are several different methods that can be used for colorimetric phosphorous determination, but they are all just variations of the same procedure. Persulfate digestion followed by colorimetric analysis tends to be the most commonly used method and is the basis of most of the following discussion.
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Wednesday, 28 November 2012 14:32 |
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Introduction – Oil and Grease (O&G) is the most method defined of all method defined parameters. For reasons
that we will explore later, a better name for this particular test would be HEM (Hexane Extractable Material). While
it is somewhat easy to say “oil and grease” and have a good idea of what is meant, it is quite difficult to come up
with a good scientific definition and even harder to design a selective test. Depending on the specific origin of
the material they can foul up water treatment processes, impart unpleasant odors or tastes to the water, or look
unpalatable.
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