Decentralized Treatment: System Features Fixed Film Media Filters, Drip Irrigation Disposal

The destruction caused by Hurricane Katrina in 2005 crippled the coastal counties of Mississippi. As a result, the Jackson County Utility Authority initiated the development of decentralized wastewater infrastructure in the hardest-hit cities of Big Point and Wade. They selected a fixed film media filter to provide advanced wastewater treatment, followed by drip irrigation to disperse the wastewater back into the environment.

Quanics Tanks 1306ww
Quanics Tanks 1306ww
The project involved installation of proprietary AeroCell System from Quanics Inc. for treatment and a Geoflow Drip Irrigation system for effluent disposal.

By Brian Borders

The destruction caused by Hurricane Katrina in 2005 has forever impacted the Gulf Coast. The devastation and subsequent rebuilding has led to a shift in ideology from just simply "building back" to "building better" to reduce the impact of a similar storm in the future.

The Jackson County Utility Authority, hard hit by the storm, recently began development of decentralized wastewater infrastructure in Big Point and Wade, Miss. Neel-Schaffer Engineering of Jackson, Miss., was selected as the design engineer for the projects. The firm selected a fixed film media filter as the technology of choice to provide advanced wastewater treatment, followed by drip irrigation to disperse the highly-treated wastewater back into the environment.

Wastewater from current and future developments will make its way to the two treatment and disposal plants through the use of a Septic Tank Effluent Pump (STEP) collection system and small diameter pressure sewers. These two treatment facilities combined will have the capability of treating up to 220,000 gallons per day. The systems are two of the largest decentralized fixed film media filters in the U.S.

Quanics Inc. of Crestwood, Ky., was selected to provide the fixed film media filters, drip irrigation equipment and engineering assistance. The company selected its proprietary AeroCell System for treatment and used Geoflow Drip Irrigation equipment for final dispersal. The AeroCell System is a pre-engineered synthetic media filter using open cell foam cubes housed inside individual fiberglass enclosures. Open cell foam has been proven over the past 19 years to effectively treat wastewater to secondary or better levels.

Further, it is a very absorptive, highly porous media and has a large surface area per unit volume, which allows effluent and air to flow freely through it at the same time. These features prevent the foam from becoming clogged over extended periods of time and allow loading rates of up to 10 times that of gravel, sand or peat moss media filters.

Higher loading rates allow the AeroCell systems to be placed in small modules, which occupy a smaller footprint compared to other advanced treatment systems. Effluent is sprayed over the foam and slowly percolates downward. As the effluent passes around and through the open cell foam media, it contacts large populations of aerobic organisms, and degradation of the wastewater strength occurs. Additional treatment occurs when the effluent is recirculated back through the system. Significant reductions in BOD, TSS, TN, and coliform bacteria can be expected through this process.

Effluent from the served structures will be pumped via STEP collection to a custom-built flow splitter that will divide the flow evenly between banks of recirculation tanks. The 40,000-gallon fiberglass tanks provided by Containment Solutions are buried below the AeroCell Treatment modules, further shrinking the system footprint.

Each recirculation tank is equipped with three separate duplex pump systems. Each pump system doses effluent to a dedicated bank of nine treatment modules. The treated effluent then flows via gravity to recirculation devices that split the flow at a 4:1 ratio (or 80 percent recirculation). Recirculation of the treated effluent is critical to achieving the desired reduction in wastewater constituents. A parcel of water on average will pass through the media filter four times before leaving this step of the treatment train.

The 20 percent discharged flows to a 40,000 gallon fiberglass dosing tank. Multiple pumps in the dosing tanks time-dose the effluent through two separate ultraviolet disinfection systems. The effluent then flows to large multi-zone drip irrigation fields for final dispersal below the ground.

Hemphill Construction of Florence, Miss., was selected as the general contractor for the project and began construction of the system in the fall of 2009. Quanics' Gulf Coast representative, J.H Wright and Associates of Daphne, Ala., provided design oversight and installation assistance throughout the course of the project.

Brian Borders, is President of Quanics Inc. He may be contacted at bborders@quanics.net.

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