Odor Control System

Editorial Emphasis

"Your treatment plant stinks again! What are you going
to do about it?" 

Whether this complaint comes directly from an offended
neighbor, or is routed through a council member or utility board, we know where
the buck stops: the WWTP manager.

Odor complaints have become an all too familiar subject to
WWTP managers. They are not only expected to manage their plants effectively
and efficiently, meeting both regulatory specs and budget requirements –
they are also expected to be good neighbors and keep odor under control. This
article describes the successful odor control efforts of the South Dearborn
Regional Sewer District located in Lawrenceburg, Ind.

 The district
provides regional wastewater treatment services for three cities and an
international distillery. The 6 mgd 
treatment plant is located in an area of high population growth, and is
surrounded by many retail operations and other commercial developments. In
addition, a heavily traveled state highway runs by the treatment plant.

As the community grew, odor complaints became a sensitive
issue, and the district sewer board was committed to solving the odor problem.
The results of the district's initial attempts to treat or mask odors
from their primary clarifiers were sometimes unsatisfactory, and it became
apparent that neighbors' perceptions did not change as long as odors were
occasionally present.

As South Dearborn Sewer District Superintendent Dennis
Feichtner found, "The district would manage odors well for 62 days in a
week and then have an unexpected 'odor event.' Then the telephone
calls would start again."

The district evaluated alternative approaches and decided to
purchase covers that would work with a ventilation and scrubber system to
positively capture, remove and treat odorous gas. With the assistance of the
district's consultants, GRW Engineers Inc., decisions were quickly made
regarding a blower and scrubber to remove and treat the gas. The
district's remaining task was to choose a cover system that captured and
contained odorous gas while providing features that best met their operational

After evaluating several cover systems, the district chose
covers fabricated and installed by Geomembrane Technologies Inc. (GTI), with
customized features to meet their operational needs, while fitting within the
constraints of existing infrastructure.

Each clarifier is covered by a high performance coated
fabric tensioned over a series of aluminum support arches placed along the
length of the clarifier tank openings. This industrial fabric is a proven
performer in a wastewater environment and features high strength, durability,
and UV protection.

Aluminum walkways divide the fabric covers into manageable
sections which are easily detached on three sides and rolled up along the
support arches to expose the tank interior for inspection or maintenance.
Hatches in the walkways are located at key points to provide access for a
single operator to take samples, inspect equipment, tip scum troughs, etc. This
easy access to the tank interior is a key feature for the district's
plant operators.

They also point out that the need for complete tank access
is not always part of a planned maintenance activity. Sometimes access is
required quickly because of mechanical problems, and the ability to easily
retract the covers without the aid of lifting equipment is a time-saving
advantage in an emergency.

A customized cover design also made the GTI system an
attractive choice for the district. Constraints imposed by the physical
configuration of mechanical and electrical systems associated with the existing
clarifiers were addressed by GTI. The cover design was modified to fit within
these constraints, rather than requiring the district to incur the additional
cost of changing their existing systems.

The district superintendent and plant operators took an
active role in planning and installing the entire odor control system. With
this assistance, the covers were installed in less than a week without taking
the clarifiers out of service. District staff installed a blower and
underground piping system between the covers and scrubber, and successfully
brought the complete system online. The district is now able to capture and
treat odors from its headworks, primary clarifiers and belt press building.

The odor control system has been operational for about one
year, and Feichtner is pleased with the project's success.

"Odors have disappeared from our plant," he
reports. "The subject of odor complaints used to arise so frequently that
it was a standard agenda item at board meetings. With our new odor control
system, odor complaints are no longer an agenda item in district sewer board
meetings. Now we receive positive comments from the public."


About the author

Brent Howe is a product line manager with Geomembrane
Technologies Inc. For further information, phone 506-452-7304.