A
PLACE TO START
Think about it -
Technical subjects are viewed through scientific measurements, For example:
- Volume in cubic mm, cm, m, etc
- Velocity in mm/sec, miles/hr, etc
- Elements in atomic weights
Each technical field has its
set of analytical tools that are used to quantify conditions, kinetics, etc.
The set of analytical tools
for the wastewater treatment field is sizeable:
- Determinations of metals
- Determinations of specific inorganic ions
- Determinations of specific organic compounds
- Respiration techniques. etc.
The environmental field has for many years used 5-day biochemical
oxygen demand as an approximation tool related to ultimate biochemical
oxygen demand. Unfortunately,
Regulatory Agencies elected to use the approximation tool as a legal
parameter, treat it as a finite analytical procedure, and made it is a legal
parameter in NPDES requirements. Thus,
BOD5 is measured daily, reported to regulatory agencies, and
regulatory action can result when a specific value is exceeded.
This status is unfortunate because:
- The BOD5 result is not finite
and specificity is only in the eye of Regulatory Agencies.
The status of BOD5, before being raised to Sainthood by
the Clean Streams Regulations of 1972, was one of “How is my process
doing?” Not
“How much work is my process dong?”
There is a big difference.
- The BOD5 relationship
to the finite ultimate biochemical oxygen demand measurement
is highly variable.
- Wastewater treatment facility performance
is being measured by a non-finite parameter that is not useful
in actual interpretation of process performance.
- Time and money is being devoted to a
measurement that has limited value, except in regulatory reporting.
- A more finite parameter has to be used to
understand process performance. Currently,
process kinetics are expressed in terms of biodegradable soluble COD
(which is seldom if ever measured). If the only process information available to the
Engineer is BOD5, where does he get soluble biodegradable COD
values? He guesses at
them.
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