Page 470 - Air Pollution Control Engineering

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442 Gregory T. Kleinheinz and Phillip C Wright

Table 11
Parameters That Are Monitored during Various Biofiltration Applications
Relative Relative Critical Information
Parameter Importance a Cost a Provided
Concentrations/removal 3 4 or 5 Critical information to assess the “performa-
of target compounds nce” of the system. However, for complex
in the airstream. odor applications complex monitoring
may not be as valuable as the smell test at
the site. This is more critical for applic-
ations where total emissions are part of a
permitting or discharge process. Often the
most costly and requires the most capital
equipment of the monitoring parameters.
Microbial counts 2 3 Since the biofilter is a living system, this is
often a cost-effective method to assess the
overall health of the system. Large increa-
ses in numbers can be problematic as it
may result in clogging of the system.
Large decreases in counts may indicate an
accumulation of toxic intermediates, cha-
nges in the airstream, or a lack of nutrients
or moisture. Counts are generally greater
6
than 1.0 × 10 Colony Forming Units
(CFU) per gram of solid support.
Moisture content of the 1 2 Inexpensive parameter to monitor and
solid support critical to good chemical partitioning and
microbial growth. It is usually desirable to
have the moisture content stable and as
close to the moisture-holding capacity of
the solid support as possible.
Nutrients (N and P) 1 3 Critical to the proper growth of microorgan-
isms in the biofilter. Proper nutrient level
have been shown to be a critical factor in
efficient biofilter operation. Usually samp-
les are collected and sent to a laboratory
that does these analyses, thus making it
a relatively easy parameter to monitor.
pH of solid support 1 2 pH of the solid support is very important to
monitor due to potential acidic intermedi-
ates which are produced by biological
oxidations. Most biofilters operate in a
pH range of 6–8.
Porosity/integrity of the 4 or 1 b 2 The porosity of the solid support is important
solid support to determine to calculate the actual
residence time in the system. It is critical
to monitor this parameter for natural solid
support materials as they will degrade over
time. By catching the degradati on of this
material early it may help the operator
avoid system failures and unexpected
down time.