Earth Complex Map
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 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 on the property of the EARTH Complex.
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 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 on the property of the EARTH Complex.
T. E. Maxson Wastewater Treatment Facility
A relatively small but key portion of the EARTH Complex is the T. E. Maxson Wastewater Treatment Facility. 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 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.
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 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.
Primary Clarifiers
Water then flows by gravity toward the next step in treatment, the primary clarifiers. 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 which is the first step of the sludge disposal
Activated Biological Filter
The effluent from the primary clarifiers flows by gravity to the (ABF) Activated Biological Filter Towers. 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.
Sewage Pump Station
Once the mixture of sewage and microorganisms reach the bottom of the ABF towers it flows by gravity to a screw pump station. These pumps lift the liquid up to a level which will allow it to flow by gravity through the remainder of the process.
Contact Tanks
During the next step in the treatment process, the sewage/microorganism mixture is held in tanks for several hours. 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 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. By this time over 95% of the original BOD and TSS has been removed from the waste stream.
Slug Storage Lagoons
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. 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 is being dewatered by belt filter presses, then stabilized by the addition of lime. Finally, both primary and waste activated sludge is applied to the sludge disposal and landfill areas or to farmland, both on the EARTH Complex site.