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Mercury
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Phase II Reports >> Facilities Loadings
Facilities Loadings
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For more
information, contact David Eppstein by email at
deppstein@masco.harvard.edu,
or by calling 617-632-2860.
2.0 GLOSSARY OF TERMS
In this report, several terms are used that may not be familiar to many
readers. For example, sewer discharges from specific types of business activities are
regulated under Sewer Use Discharge Permits issued by the MWRA. Following MWRA practice,
the permitted sewer discharges are called "industrial" discharges in this
report.
As another example, many but not all MWRA Sewer Use Discharge Permits
require the permit holders to periodically collect and analytically test representative
discharge samples. In this report, discharge pollutant loadings calculated for the
discharges having sample analytical data are called "known" loadings.
In addition, as described later, the Subgroup calculated overall
mercury discharge concentration averages from available analytical test data for each of
the five groups of facilities studied. Calculated over half-year intervals, these average
concentrations are called "Group Concentration Averages (GCA’s)" in this
report.
These terms and several others are defined in the following Glossary of
Terms. The Glossary includes definitions of each of the five study groups, the statistical
term of outlier, three basic terms relating to sewage (concentration, flow, and sampling
location), and two summary loadings terms (total industrial loading and total system
loading).
GLOSSARY OF TERMS
Clinical Laboratories - Facilities that perform analytical testing
of tissue and fluid samples from animal or human sources for medical diagnostic purposes.
Concentration - The total mass of a suspended or dissolved
constituent in a unit volume of wastewater, typically expressed in units of either
milligrams per liter (mg/L) or micrograms per liter (µg/L). These units are sometimes
called parts per million (ppm) and parts per billion (ppb), respectively.
Discharge Loading - The total mass of a suspended or dissolved
constituent in a wastewater discharge over a fixed period, typically expressed in units of
pounds per day (lbs/day). It can be calculated by multiplying a measured concentration
value by an associated flow value and an appropriate units conversion factor.
Flow - A volume of liquid per unit time, typically expressed for
wastewater discharges in units of gallons per day (gpd).
Group Concentration Average (GCA) - In this study, the average
mercury concentration for a specified group of discharges calculated by averaging
individual discharge concentration averages.
Hospital Laundries - Facilities that directly serve a hospital in
the laundering of linens, gowns, and lab coats.
Known Discharge Loading - A discharge loading for an MWRA permitted
sampling location that has both concentration test data and a measured or estimated flow.
Medical Waste Incinerators - In this study, facilities that burn
hospital waste or medical/infectious waste and use a wet scrubber for reducing air
pollutant emissions.
Other Facilities - In this study, facilities that perform any
hospital-like function. Such facilities included college laboratories, steam suppliers,
pharmaceutical manufacturers, and testing laboratories.
Outlier - An unusually high or low value in a data set, typically
identified by comparison to a statistical limit.
Research Laboratories - In this study, facilities that conduct
medical or biotechnology research.
Sampling Location - An industrial waste sewer discharge point,
defined in a MWRA Sewer Use Discharge Permit, at which representative waste samples are
collected for analysis.
Total Industrial Loading - The total mass of a suspended or
dissolved constituent discharged in all MWRA permitted sewer discharges over a fixed
period, typically expressed in units of pounds per day (lbs/day). It can be calculated by
determining the sum of individual Known Discharge Loadings (see above for definition).
Total System Loading - The total mass of a suspended or dissolved
constituent contained in sewage that enters a sewer system or municipal treatment plant
over a fixed period, typically expressed in units of pounds per day (lbs/day). It can be
calculated by multiplying a measured treatment plant influent concentration value by an
associated flow value.
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