Page 12 - Nov-Dec18

TDEC
Wastewater Optimization Program
Communities frequently begin
energy-efficiency projects with lighting
or mechanical system upgrades in public
buildings, or by looking at the fuel
efficiency of their vehicles. However,
one of the largest energy-consuming
operations in most cities is often a
missed opportunity: drinking water and
wastewater treatment systems. Nationally,
three to four percent of all electricity
produced is used for treating wastewater
and distributing drinking water.
Typically, these systems account
for 35 percent of a city’s municipal
energy budget. Of that, 60 percent of
a wastewater treatment plant’s energy
consumption is for aeration. For
decades, wastewater operators were
taught to aerate 24/7/365 to ensure
compliance. Energy conservation was
not a priority, since most staff never saw Moore, Professor of Civil Engineering
their energy bills.
To address energy conservation
and other operational practices, the
Tennessee Department of Environment
and Conservation (TDEC) Division of
Water Resources and Office of Policy
and Sustainable Practices created the
Tennessee Water and Wastewater Energy
Efficiency Partnership in 2011 with EPA
Region 4, the University of Tennessee
Municipal Technical Advisory Service
(MTAS), the Tennessee Valley Authority
(TVA), and the University of Memphis.
The goal of the Partnership was to
provide a more focused process and
resources to help utilities understand
the impact of energy use and to identify
opportunities for energy conservation
through optimization.
From 2011 to 2015, the Partnership
provided no-cost technical assistance to
water and wastewater systems to identify
operational strategies, which, once
implemented, resulted in reduction in
energy usage, energy cost savings, and
often a reduction in nutrient discharge.
Fewer nutrients lead to cleaner streams
and rivers. In 2016, the U.S. Department
of Energy provided a State Energy
Program Competitive Award to the
TDEC Office of Energy Programs to
continue the efforts of the Partnership
while helping the State of Alabama
12 TPW November/December 2018
After studying
plant operations
at Covington
WWTP, the team
recommended
turning off their
mixers (pictured)
part of the day.
implement a similar program.
Since 2011, the Partnership has
assessed 41 water and wastewater
systems across Tennessee and conducted
14 workshops to train operators
how to better run their facilities. The
Partnership has also worked directly
with operators to implement no-to-low-
cost recommendations, such as on/off
aeration cycles, which can greatly reduce treatment plants (WWTPs) invited
a facility’s total energy use.
The assessments relied on the Bio-
Tiger model developed by Dr. Larry
at the University of Memphis. His
model was packaged into a user-friendly
spreadsheet that allows operators to
compare different operational scenarios
and may be found on TDEC’s website
along with a training video and user
manual.
The Partnership is an excellent example the operating time of the aerator in the
of governmental entities, utilities and
public higher education institutions
working together to better our
communities and environment. Water
and wastewater systems participating
in the Partnership identified potential
By Ashley Cabrera
measures which would result in
significant annual energy savings of over
17,000,000 kilowatt-hours (kWh) and
cost savings of $2 million. Approximately
40 percent of those identified measures
have been implemented. The Partnership
continues to work with systems to
increase implementation of optimization
measures. On average, implementation
of the Partnership’s recommendations
reduces a system’s annual energy costs
by nearly 20 percent and, in some cases,
reduced total nutrient discharge by 40
percent.
The Carthage Wastewater Treatment
Plant was one of many wastewater
to participate in the partnership. This
WWTP has a design capacity of 625,000
gallons per day (gpd), and currently
treats about 330,000 gpd of municipal
wastewater. The plant has an annular
aeration basin with a final clarifier in
the center. Bio-solids generated during
treatment are further treated in two
aerobic digesters, operated in series.
The team recommended reducing