EL Paso, TX
Frontera Pump Station
CH2MHill designed the 8ft diameter ECO2 System, which has the capacity to add up to 5,000 lbs/day of oxygen to the 3.5 mile long Frontera Dual Force Main.
With the goal of reducing odors at and around its wastewater treatment plant adjacent to Interstate Hwy I-10 and new development, El Paso Water Utilities hired CH2MHill to study, design and manage the construction of odor improvements at the Northwest WWTP.
The study included a comparison of five traditional odor control chemicals and ozonization with SuperOxygenation and concluded, based on lowest life-cycle cost, that EPWU pre-purchase and install an ECO2 SuperOxygenation System at the Frontera Pump Station, upstream of the plant.
The ECO2 System was expected to perform better than the previously used calcium nitrate at approximately 40% of the cost.
El Paso Water Utilities operates the Northwest WWTP at the northwest side of the City of El Paso, TX. The NWWWTP has a capacity of 17.5 MGD and currently treats 9-10MGD ADF.
Odor emissions at the plant are directly related to wastewater entering the front end of the plant from the collection system, mainly the Frontera Pump Station.
Frontera Pump Station
The Frontera Pump Station lies about 3.5 miles upstream of the NWWWTP and conveys over 90% of the flow to the plant (5-8.5 MGD).
3.5 Mile long Dual Force Main
The dual force main leading from Frontera PS to the plant is 3.5 miles long and consists of 30’’-, 36’’-, and 42’’ diameter sections. The overall HRT exceeds 12 hours at times, resulting in extremely high sulfide concentrations of up to 20mg/L in the liquid phase.
Start-Up and Performance Testing
Due to the lack of a flowmeter the System had to be programmed manually during the first two weeks of operation. Based on estimated flows and H2S concentrations at the plant the oxygen feed rate was optimized to achieve the following results:
- Reduced Odor Emissions at NWWWTP headworks & plant
- Reduced Concentrations of dissolved sulfides at headworks
- Reduced chemical consumption at existing chemical scrubber
ECO2 System Installation
Typically, ECO2 SuperOxygenation Systems are installed on force mains, taking advantage of the “free” pressure to dissolve high levels of oxygen into the side stream. The operation is automated based on flow meter signals that allow the ECO2 PLC to flow-pace the oxygen feed, effectively preventing H2S formation.
The El Paso Installation posed some challenges along the way for the design team. The station does not employ flow meters and low pressures limit the amount of oxygen that can be added. Additionally, flows from two smaller force mains feed into the force main, which cannot be controlled with one system.
H2S Concentration at Dischange of Frontera Dual Force Main
At 40% of the cost, the ECO2 System lowers the avg. H2S level from 12ppm with calcium nitrate feed to 1ppm with oxygen.
Become a leader in water treatment.
ECO2 SuperOxygenation systems for water and wastewater treatment are designed and produced by Eco-Oxygen Technologies, LLC headquartered in Indianapolis, Indiana. The technology is the pioneering effort of Dr. Richard Speece, Centennial Professor Emeritus of Civil and Environmental Engineering at Vanderbilt University.
The ECO2 oxygenation method is a simple process based upon the scientific principle of Henry’s Law. No chemicals and no moving parts other than standard industrial water pumps are used. The result is a robust, reliable, economically competitive and environmentally friendly technology.
In municipal applications, ECO2 technology eliminates hydrogen sulfide odor and corrosion by dissolving pure oxygen in wastewater at high concentrations (50-75 mg/l) which prevents the formation of hydrogen sulfide and the associated “rotten-egg” odor. This approach saves money on alternative chemicals, provides pretreatment and does not increase total dissolved solids. ECO2 engineers are presently focused on wastewater projects in Maine, Indiana, California, Kentucky and Texas.