Membrane Filtration. A method of quantitative or qualitative analysis of bacterial or
particulate matter in a water sample by filtration through a membrane capable of
Meter. A unit of length; 100 centimeters; 1,000 millimeters; a device for measuring the
flow of fluid.
Microorganism. A minute plant or animal in water or earth that is visible only through a
Milligrams Per Liter. A unit of the concentration of water or wastewater constituent. It
is 0.001 g of the constituent in 1,000 ml of water. It has replaced the parts per million
unit, to which it is approximately equivalent, in reporting the results of water and
Mineral. (1) Any of a class of substances occurring in nature, usually comprising
inorganic substances (such as quartz and feldspar) of definite chemical composition
and usually of definite crystal structure, but sometimes also including rocks formed by
these substances as well as certain natural products of organic origin, such as asphalt
and coal. (2) Any substance that is neither animal or vegetable.
Mixer, Flash. A device for quickly dispersing chemicals uniformly throughout a liquid.
Mole. Molecular weight of a substance expressed in grams.
Most Probable Number (MPN). The best estimate, according to statistical theory, of the
number of coliform (intestinal) organisms present in 100 ml of a water sample.
Mud Balls. The end results of the cementing together of sand grains in a filter bed by
gelatinous material, such as a coagulant. They may vary in size from a pea to 1 to 2
inches in diameter.
Nitrogen Cycle. The unending cycle in nature through which the nitrogen passed from
plant and animal proteins, to organic nitrogeneous material, to ammonia, to nitrites, to
nitrates, and then to plant and animal proteins again.
Noncommunity Water System. A public water system that is not a community water
Nonpotable Water. Water that has not been examined, properly treated and approved
by appropriate authorities as being safe for domestic consumption. All waters are
considered nonpotable until declared potable.
Operating Log. Daily detailed records of operation.