The City of Milford, CT has an extensive sewerage system that has been plagued by odor complaints for many years. High levels of hydrogen sulfide (H2S) have caused severe damage to the sewer system, a key pump station and the wastewater treatment plant itself. The main cause of the problem was isolated to 13,200ft long, dual force mains, carrying an average of 3MGD from the Gulf Pond PS into the East/West Interceptor and ultimately, another mile to the West Ave. PS. Measurements of atmospheric H2S in a manhole downstream of the force main discharge were as high as 900ppm.
All of the manholes on the East West Interceptor were badly deteriorated and the ductile iron sewer had developed perforations along the spring line of the pipe and had to be replaced. Effects of H2S at the WWTP were not as severe as at the West Ave. PS, but still noticeable, including metal corrosion and persistent odors.
Innovative and highly effective, SuperOxygenation technology is an eco friendly alternative to traditional chemical treatments for water and wastewater. Focusing on odor and corrosion prevention, ECO2 has helped cities across the country solve their needs in both municipal and industrial applications.
AECOM used a two pronged approach to eliminate the generation of hydrogen sulfide. The first part consisted of flow optimization to reduce the hydraulic retention time in the force main. Flow meters, motorized valves and a PLC were installed to control the usage of the two force mains.
The second part consisted of introducing a sidestream flow saturated with pure oxygen to satisfy the oxygen demand in the force main. By maintaining a positive D.O. level in the force main, sulfide formation is prevented and H2S odor and corrosion eliminated.
An ECO2 SuperOxygenation System was installed in 2012 at the Gulf Pond Pump Station in Milford, CT. The SuperOxygenation System is designed to dissolve 1,000 lbs/day of pure oxygen into a 1,000gpm wastewater sidestream. The sidestream is pulled from the discharge header of the force main pumps, is run through the ECO2 Speece Cone, where it is oxygenated, and then discharged back into the force main. The ECO2 System takes advantage of the “free” pressure from the force main and raises the D.O.
ECO2 SuperOxygenation System consisting of: 4ft dia. Speece Cone, PLC & O2 Flow Controls (pump not shown) to the saturation level without further pressurizing the system, minimizing O&M costs.
Testing done during startup of the system indicated 95% to 98% oxygen transfer efficiency. Only dissolved oxygen is blended back into the force main, no bubbles or “micro- bubbles” are introduced into the line to avoid air locking pipes or pumps. All openings on the ECO2 System are a minimum of 4’’ in diameter, capable of passing dirty wastewater without clogging. The system is controlled by a PLC and an oxygen flow control panel that administer the right amount of oxygen based on real time flow data.
The system operates automatically with basically no need for maintenance. The only moving part that requires standard maintenance is the side stream pump.
Gulf Pond Force Main
|Diameter||20 and 24||in.|
ECO2 System Design
|D.O at Discharge||83||mg/l|
|O2 Transfer Efficiency||95 - 98||%|
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.