Benton Utilities Wastewater Treatment Dept.

The Benton Utilities Wastewater Treatment Plant is the location where wastewater is treated and released into the environment after water quality standards are met as set forth by the Arkansas Department of Environmental Quality (ADEQ) and the Environmental Protection Agency (EPA). The wastewater treated at our facility consistently exceeds these standards.

The manager of the Benton Utilities Wastewater Treatment Plant is responsible for executing the daily activities in this Plant and coordinating these with the Benton Utilities General Manager.  In addition to the manager, there is a foreman, a chemist, and eight other operators employed at the plant. The crew works hard to accomplish the duties they are assigned to keep this plant operational 24 hours a day. While the plant is staffed and continually operational 24/7; it is closed to the public after regular office hours.

What is wastewater treatment?

It's the process of removing cantaminants from used water to make it safe for discharge or reuse, protecting public health and the environments.  

How do treatment plants protect our water?

Wastewater treatment plants:  Remove solids, everything from rags and plastics to sand and smaller particles found in wastewater;

Reduce organic and inorganic matter and pollutants--naturally occurring helpful bacteria and other microorganisms consume organic matter in wastewater and are then separated from the water; and,

Restore oxygen--the treatment process ensures that the water put back into our streams has enough oxygen to support life.

Where does wastewater come from?

Angela Freeman, Chemist, completes testing daily to keep us in compliance with the EPA & ADEQ

Homes--human and household wastes from toilets, sinks, baths, dishwashers, garbage grinders, clothes washers and drains.

Industry, Schools, and Business--chemical and other wastes from factories, food-service operations, school activities, hospitals, shopping centers, etc.

On the average, each person in the U.S. contributes 100 gallons of wastewater every day. If you include industrial and commercial water uses, the per person usage of water is as high as 150 gallons per day.

Wastewater treatment basically takes place in three stages:

1. Primary treatment, which removes 40-60% of the solids.
2. Secondary treatment, which removes about 90% of the pollutants and completes the process for the liquid portion of the separated wastewater.
3. Sludge (bio-solids) treatment and disposal.

Preliminary Wastewater Issues

STEP 1 - Sanitary sewers carry wastewater from homes and businesses to the raw wastewater pumping station at the treatment plant. The wastewater flows by gravity most of the time in the sanitary sewer pipes. Routine cleaning and closed circuit television inspection of Benton's sanitary sewer lines helps keep the sewer collection system in good shape.

STEP 2 - Fine Screens let water pass, but not trash (such as rags, diapers, etc.). There are four screens located at the plant. The trash from these screens is collected and properly compacted by bar screens and disposed of at the landfill. The screened wastewater is pumped to the two aeration basins.

Primary Treatment

STEP 1 - The Aeration Basin supplies adequate amounts of air to the mixture of primary wastewater with the help of natural occurring bacteria and the other microorganisms that consume the organic matter. The growth of the helpful bacteria and microorganisms is speeded up by vigorously mixing air (aeration) with the concentrated microorganisms in the activated sludge and the wastewater. Adequate oxygen is supplied to support the biological process at a very active level. The ratio of food to micro-organisms is continually monitored and adjusted to meet daily variations in the wastewater.

STEP 2 - Three Secondary Clarifiers allow the bio-solids of biological mass (the microorganisms) to settle from the water by gravity. 90-95% of this mixture, called "activated sludge," is returned to the aeration basins to help maintain the needed amount of microorganisms. The remaining 5-10 % is pumped to the aerobic digester.

STEP 3 - Three Digesters provide the final step for the bio-solids before removal from the system. They are very slow turning clarifiers. Bio-solids are then removed from the system being pumped through a filtered belt press and either being process using a Fulton Dryer or sent to the landfill.

The bio-solids removed from the filtered belt press are then transferred to the dryer which then makes these bio-solids usable by turning them into a class A bio-solid which can be used anywhere according to EPA Regulations or disposed of at the local landfill.

STEP 4 - The final effluent (liquid portion from Step 2) travels through the Ultra Violet Disinfection System.  Itt is a physical process that instantaneously sterilizes microorganisms as they pass by ultraviolet lamps submerged in the effluent. The process adds nothing to the water but UV light, and therefore, has no impact on the chemical composition or the dissolved oxygen content of the water. In that respect, it ensures compliance with ever-tightening wastewater effluent discharge regulations.

All effluent returned to natural bodies of water must meet National Pollutant Discharge Elimination System (NPDES) criteria. The final effluent is monitored daily. In-house laboratory staff perform sampling and analysis for process control and NPDES compliance.

The bio-solids are utilized in an environmentally acceptable manner as a beneficial soil conditioner. The bio-solids applied to all sites are monitored for nutrients, metals, other compounds and pathogens.

Specialty Equipment Utilized by this Department

Mack Tanker Truck – This 4,700-gallon truck is primarily utilized to clean out wet wells, manholes, and clarifiers throughout the treatment plant.  It is also used to pump out lift stations when a pump fails throughout the city.  The city has over 90 lift stations that Benton Utilities directly controls. 

Bypass pump – A 6” portable bypass pump is operated at lift stations and line breaks for both the wastewater collection system and treatment plant. The pump is designed to pump both solids and liquids.

Equalization Basin

The 57-million-gallon Equalization Basin is designed to contain diverted flow from the Wastewater Treatment Plant.  The basin has a storage capacity of eight days’ worth of inflow. This allows the treatment plant to manage the wastewater flow to allow for better treatment control. The equalization basin has a generator onsite for backup   power should it lose commercial power.

Benton Utilities was mandated by the Arkansas Department of Energy and Environment, Department of Environmental Quality (DEQ) in April 2005 by a Consent Order (CAO LIS No 05-158; April 2005 – August 2025) mandating the City of Benton to build an equalization basin due to high inflow and infiltration at the Wastewater Treatment Plant. The basin is sized to control the peak flows that occur during wet periods of the year. These inflows can increase as much as three times the design flow capacity of the Wastewater Treatment Plant which is currently 8.3 million gallons per day. The basin was completed and put in service in October 2007. In August 2025, all requirements were met in accordance with the Order and Agreement section of the consent order, and it was formally closed.

Benton Utilities has reduced the amount of inflow and infiltration into the collection system by continuing a pipe bursting program which replaces damaged and aged sewer pipe with new and upsized piping.

Back-up Generators – The treatment plant has four generators used to maintain operational controls of the facilities equipment in the event of the loss of commercial utility power.

In the event of such an outage these generators automatically convert to from commercial to generator power.

Conclusion

Benton Utilities continues to efficiently treat the city’s wastewater.  This is an ongoing and never-ending process.  We as an organization will strive to continually provide better treatment to better serve the wastewater needs of the City of Benton.