T. E. Maxson Wastewater Treatment Facility
Our first stop on our Memphis Field Trip will be
at the EARTH Complex/T.E. Maxson Wastewater Treatment Plant located at
2685 Steam Plant
Rd. Memphis, TN 38109. The EARTH Complex (Environmental and Resource Technology
Complex) provides the city of Memphis with an environmentally friendly
system for solid waste and sludge disposal combined with a research and
wildlife habitat. This system produces an ecosystem which is mutually beneficial
to both humans and wildlife. Our contact person for the tour is Peter Alfonzo,
Plant Manager.
During the tour, we will spend approximately 30 minutes inside the conference room of the plant. Mr. Alfonzo (or a representative) will discuss the history of wastewater treatment in the city. He will then show an aerial view of the EARTH Complex (shown right) and discuss the current operation of the plant and the entire complex. After the brief overview, we will tour the wastewater treatment plant and then the rest of the complex. The entire tour will last approximately 2 hours. During the summary of this tour, I will refer to the map to the right and will reference it by referring to a number which is related to a particular location. For example: there is a Wildlife Reserve (6) on the property of the EARTH Complex.
Below is a description of the T. E. Maxson Wastewater treatment plant. Follow this link for an overview of the EARTH Complex in general.
A relatively small but key portion of the EARTH
Complex is the T. E. Maxson Wastewater Treatment Facility (1). Historically,
wastewater produced by the citizens and businesses of Memphis was dumped
untreated into the rivers, creeks and ditches in and around the city. The
first attempt to treat a portion of this wastewater was made in 1975 with
the opening of the T. E. Maxson Treatment Facility. This plant now serves
a population of over 300,000 people in the southern half of the City and
County. The plant pictured below will also be used for reference and is
labeled just as the aerial map above is except with letters instead of
numbers. Please refer to the diagram as necessary during the discussion
of the wastewater treatment plant.
Wastewater
is transported to the plant through hundreds of miles of sewers, mostly
by gravity. The sewage enters the plant through one interceptor sewer which
is about 40 feet below ground. The first step in the treatment of this
sewage is the removal of large objects that might damage downstream pumps
and equipment. Bar screens (A) are designed for this purpose. In addition,
grit tanks (C) are designed to remove the heaviest particles (such as sand)
from the wastewater. Grit and debris from the bar screens are placed into
trucks and hauled away to a local landfill (N).
Water then flows by gravity toward the next step in treatment,
the primary clarifiers (D - also pictured right). These clarifiers utilize
gravity along with long detention 
time
to remove Biochemical Oxygen Demand (BOD) and
Total
Suspended Solids (TSS) in wastewater that readily settle to the bottom
of the tank. This material is now called primary sludge. This sludge is
pumped to the primary sludge dewatering facility (J) which is the first
step of the sludge disposal process.
The effluent from the primary clarifiers flows by gravity to the (ABF)
Activated Biological Filter Towers (E - also pictured left). There are
four ABF towers which represent the first stage of the biological treatment
process. Thousands of pounds of microorganisms (recycled from the secondary
clarifiers) are added to the primary clarified effluent and pumped to the
top of these towers. The liquid is sprayed over the surface of each tower
and it trickles through 21 feet of wooden slats. Each slat is covered
by live microorganisms which include numerous varieties of bacteria as
well as rotifers, ciliates, flagellae and many other life forms. Aerobic
conditions dominate this process because the natural draft going through
the towers helps to speed the treatment process and minimize foul odors.
Once the mixture of sewage and microorganisms reach the
bottom of the ABF towers it flows by gravity to a screw pump station (pictured
right). These pumps lift 
the liquid up to a level which will allow it to flow by gravity through
the remainder of the process.
During the next step in the treatment process, the sewage/microorganism
mixture is held in tanks for several hours (F). These tanks, called contact
tanks, contain huge blowers which constantly force air into the liquid.
This air creates an ideal aerobic environment for the completion of the
biological degradation of the organic portion of the sewage. Finally, the 
liquid flows to the secondary clarifiers (G - also pictured left) where
microorganisms settle to the bottom and clear effluent overflows the clarifiers
on the surface. The effluent is then discharged directly into the Mississippi
River (I). By this time over 95% of the original BOD and TSS has been removed
from the waste stream.
A portion of the microorganisms that settle to the bottom
of the clarifier is pumped back to the ABF tower for reuse. The 
rest is pumped as waste activated sludge (WAS) to a series of five sludge
storage lagoons (K - also pictured right). It is held in these lagoons
for over a year. During this time, the sludge thickens and reduces in volume.
During the same amount of time, over 99.99% of the disease causing organisms
die and nature converts 50% of the sludge solids into harmless gases through
a slow anaerobic degradation process. One of these gases, methane, is pumped
to nearby TVA methane power station. Simultaneously, the primary sludge
(from above) is being dewatered by belt filter presses (J - also pictured
left), then stabilized by the addition of lime (L). Finally, both primary
and waste activated sludge is applied to the sludge disposal and landfill
areas (2) or to farmland (5), both on the EARTH Complex site.
| Overview of the EARTH Complex.
Next site on the trip. |
 |
 Questions/Comments? |
T. E. Maxson Wastewater Treatment Facility, City of Memphis, Division of Public Works in Cooperation with City Beautiful (1990).
Graphics:
Aerial Map, T. E. Maxson Wastewater Treatment Facility, City
of Memphis, Division of Public Works (May 15, 2003).
Wastewater Treatment Plant Schematic, T. E. Maxson Wastewater Treatment Facility, City of Memphis, Division of Public Works (May 15, 2003).
Photos:
Thomas, Donna (May 2003).
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