There
is generally increasing public concern and intolerance of
odor and other air emissions from wastewater facilities.
Management of air emissions has become a significant activity
as most wastewater treatment facilities in Alabama and throughout
the United States want to be good neighbors. There are several
types of odor treatment technologies that can be effectively
used to treat foul air emissions from wastewater pump stations
and WWTPs. This presentation addresses and compares three
common odor treatment technologies: chemical scrubbing, biofiltration
and air ionization. The presentation will also highlight
features of the biofilter system being installed at the Messerly
Water Pollution Control Facility in Augusta, Georgia this
year. The purpose of the presentation is to present practical
case studies of several odor control studies and design projects
that evaluated capital and annual costs, odor treatment effectiveness,
flexibility and other evaluation criteria to select the preferred
odor treatment technology. Multi-stage chemical scrubbers
are used commonly for odor treatment because the process
is proven and effective in removing a wide-range of odorants,
especially ammonia and hydrogen sulfide. The chemical scrubber
operation is flexible and allows a higher degree of treatment
with increased chemical dose. However, chemical scrubbers
have relatively high O & M cost and many WWTP operators
do not like the handling of hazardous chemicals that may
be required. Biofilters are one of the most common odor treatment
technologies used at wastewater pump stations and WWTPs.
They are typically selected because of the lower capital
and O & M Costs,
operational simplicity and overall effectiveness. Biofilters
can either have an open bed arrangement or enclosed in a vessel.
Both inorganic and organic media have been effectively used.
However, biofilters require more space than chemical or
biological scrubbers. Air ionization is a relatively new odor
treatment technology at pump stations or WWTPs in the United
States. However, it has been successfully used in Europe to treat
foul air generated from sewers, pump stations, headworks, primary
clarifiers, solids storage tanks and solids thickening and dewatering
areas at over 75 WWTPs. An ion generator placed in the HVAC ductwork
generates millions of positively and negatively charged oxygen
molecules, or ions that fill the ventilated room space. These
ions form oxygen rich clusters that interact with the foul air
in the room and kill bacteria and neutralize the odor. Pilot
testing of air ionization is recommended.
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