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M Alkalinity |
Methyl orange alkalinity.
(See total alkalinity.) |
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Macroreticular |
A term applied to ion
exchange resins that have a rigid polymer porous network in which there
exists a true pore structure even after drying. The pores are larger than
atomic distances and are not a part of the gel structure. |
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Magnesium |
One of the elements in the
earth's crust, the compounds of which when dissolved in water make the
water hard. The presence of magnesium in water is a factor contributing to
the formation of scale and insoluble soap curds. |
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Manganese |
An element sometimes found
dissolved in ground water, usually with dissolved iron but in lower
concentration; causes black stains and other problems similar to iron. It
can be removed by a water softener or it can be precipitated by chlorine
at a pH of 9.5 or above. |
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Manganese Greensand |
Greensand which has been
processed to incorporate in its pores and on its surface the higher oxides
of manganese. The product has a mild oxidizing power, and is often used in
the oxidation and precipitation of iron, manganese and/or hydrogen
sulfide, and their removal from water (see greensand, manganese zeolite). |
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Manganese Zeolite |
Synthetic gel zeolite which
has been processed in the same manner as manganese greensand, and used for
similar purposes. |
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Maximum Contaminant
Level (Mcl) |
The highest level of a
contaminant that EPA allows in drinking water. MCLs ensure that drinking
water does not pose either a short-term or long-term health risk. EPA sets
MCLs at levels that are economically and technologically feasible. Some
states set MCLs which are more strict than EPA's. |
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Maximum Contaminant Level
Goal (Mclg) |
The level of a contaminant
at which there would be no risk to human health. This goal is not always
economically or technologically feasible, and the goal is not legally
enforceable. |
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Mbas |
Abbreviation for "Methylene
Blue active Substance". |
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Mcl |
Abbreviation for
"Maximum Contaminant Level"; the maximum allowable concentration
of a contaminant in water as established in the U.S. EPA Drinking Water
Regulations. |
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Mechanical Filter |
A filter primarily designed
for the removal of suspended solid particles, as opposed to filters with
additional capabilities. |
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Media |
The plural form of
"medium". |
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Medium |
A material used in a filter
bed to form a barrier to the passage of certain suspended solids or
dissolved molecules. |
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Methylene Blue Active
Substances |
Chemical compounds which
react with methylene blue to form a blue compound which can be used to
estimate the concentration by measurement of the depth of color.
Substances measured include ABS and LAS types of detergents, thus the term
is commonly used as an expression of detergent concentration. (See
detergent.) |
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Mg/L |
The abbreviation for
milligrams per liter. |
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Micrometer |
Formally known as micron. A
linear measure equal to one millionth of a meter or .00003937 inch. The
symbol for the micrometer is "um". |
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Micron |
See micrometer. |
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Micron Rating |
The term applied to a
filter medium to indicate the particle size above which all suspended
solids will be removed throughout the rated capacity. As used in industry
standards, this is an "absolute" not "nominal" rating. |
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Microorganisms |
Tiny living organisms that
can be seen only with the aid of a microscope. Some microorganisms can
cause acute health problems when consumed in drinking water. Also known as
microbes. |
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Mil |
One thousandth of an inch. |
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Milli |
The prefix used with units
of measure to indicate one thousandth of the unit. Example: a milliliter
is one thousandth of a liter. |
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Milligram Per Liter
(Mg/L) |
A unit concentration of
matter used in reporting the results of water and waste water analyses. In
dilute water solutions, it is practically equal to the part per million,
but varies from the ppm in concentrated solutions such as brine. As most
analyses are performed on measured volumes of water, the mg/l is a more
accurate expression of the concentration, and is the preferred unit of
measure. |
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Millimicron |
(archaic) See
"nanometer". |
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Mineral |
A term applied to inorganic
substances such as rocks and similar matter found in the earth strata, as
opposed to organic substances such as plant and animal matter. Minerals
normally have definite chemical composition and crystal structure. The
term is also applied to matter derived from minerals, such as the
inorganic ions found in water. The term has been applied to ion
exchangers, stemming from the early use of natural zeolite. The term is
inappropriate to the modern organic ion exchange resins. |
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Mineral Acidity |
Acidity due to the presence
of inorganic acids such hydrochloric, sulfuric and nitric acids, as
opposed to acidity due to carbonic acid or organic acids. |
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Mole |
6.02 x 1023 atoms of an
element or 6.02 x 1023 molecules of a chemical compound. The weight of one
mole of an element is equal to its atomic weight in grams; the weight of
one mole of a compound is equal to its molecular weight in grams. |
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Molecule |
The simplest combination of
atoms that will form a specific chemical compound; the smallest particle
of a substance which will still retain the essential composition and
properties of that substance, and which can be broken down only into atoms
and simpler substances. |
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Monitoring |
Testing that water systems
must perform to detect and measure contaminants. A water system that does
not follow EPA's monitoring methodology or schedule is in violation, and
may be subject to legal action. |
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Most Probable Number (Mpn) |
The term used to indicate
the number of microorganisms which, according to statistical theory, would
be most likely to produce the results observed in certain bacteriological
tests; usually expressed as a number per 100 ml of water. |
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Mpn |
The abbreviation for
"most probable number". |
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