Down the Drain: Wastewater Treatment

The water we use every day in Marshall travels 15 miles to get to us. We flush the toilet … open the drain in the sink … and it’s gone.

But what happens to that water? It ends up at the City of Marshall Wastewater Treatment Plant. 

The sanitary sewer collection and outfall system is more than 230 miles of pipes, ranging in size from six inches in diameter to 33 inches in diameter. 

The average household discharges close to 4,000 gallons of sewage each month. Treatment plant operators ensure that every step in the process is done according to state and federal rules and environmental regulations.

The City of Marshall is making big investments in infrastructure throughout this plant, updating processes and replacing aging equipment at a cost in excess of $50 million over the next six years. The Wastewater Treatment process is outlined below in six steps.

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water down the drain
WWTP Plant
wastewater treatment steps

Step 1: Wastewater passes through a mechanical bar screen, grit chambers and clarifiers that remove large debris, sand, and heavy solids. These materials are separated for further processing, and the remaining water moves on for additional treatment.

Step 2: The water flows over rock or plastic media where beneficial microorganisms attach and form a biological layer. These microorganisms begin breaking down organic pollutants.

Step 3: The partially treated wastewater is then mixed with microorganisms from earlier stages, and air is added. This creates oxygen-rich conditions that allow microorganisms to further reduce organic material and nutrients.

Step 4: Wastewater enters settling tanks where the biological material sinks to the bottom. Clear, treated water flows out of the tank for final treatment. 

Step 5: A portion of the settled biological material is returned to the aeration process to maintain effective treatment in Step 5. Excess material is removed and sent for further processing and disposal.

Step 6: In this final step, the treated wastewater is disinfected using ultraviolet light and then safely released into the Sabine River system. 

Wastewater Treatment Plant

wastewater treatment plant - aerial