Basic Units of Measurement and Conversions - Basic Mathematics for Water and Wastewater Operators - page 72

C onversion f aCtors for a ir p ollution M easureMents
The USEPA Part 503 regulation establishes requirements for sewage biosolids-only
incinerators. The rule covers the biosolids feed, the furnace itself, the operation of
the furnace and the exhaust gases from the stack. It is the exhaust gases, potential
air pollutants, that are of interest to us here. Simply put, wastewater plant managers
and operators and responsible persons in charge of the proper operation biosolids
incinerators must be aware of not only regulatory compliance requirements but also
air pollution control parameters and associated air pollution measurements.
Air pollutant emissions are commonly stated in metric system whole numbers. If
possible, the reported units should be the same as those that are actually being mea-
sured. For example, weight should be recorded in grams, and volume of air should
be recorded in cubic meters. When the analytical system is calibrated in one unit,
the emissions should be reported in the same units of the calibration standard. For
example, if a gas chromatograph is calibrated with a 1-ppm standard of toluene in
air, then the emissions monitored by the system should also be reported in ppm.
Finally, if the emission standard is defined in a specific unit, the monitoring system
should be selected to monitor in that unit. Tables 2.9 and 2.10 illustrate the conver-
sions of various volumes to attain 1 part per million (ppm) and conversions for parts
per million in proportion and percent.
The preferred reporting units for the following types of emissions are

Nonmethane organic and volatile organic compound emissions ppm, ppb

Semi-volatile organic compound emissions µg/m 3 , mg/m 3

Particulate matter (TSP/PM-10) emissions µg/m 3

Metal compound emissions ng/m 3

Conversion from ppm to µg/m 3
Often, the environmental practitioner must be able to convert from ppm to µg/m 3 .
Following is an example of how one would perform that conversion using sulfur
dioxide (SO 2 ) as the monitored constituent.

TABLE 2.9
Conversion for Various Volumes to Attain One Part
Per Million

Amount of Active Ingredient Unit of Volume Parts per Million

2.71 pounds Acre-foot 1 ppm

1.235 grams Acre-foot 1 ppm

1.24 kilograms Acre-foot 1 ppm

0.0283 grams Cubic foot 1 ppm

1 milligram Liter 1 ppm

8.34 pounds Million gallons 1 ppm

1 gram Cubic meter 1 ppm

0.0038 grams Gallon 1 ppm

3.8 grams Thousand gallons 1 ppm