The ECO₂ SuperOxygenation system is the technology of choice for supplementing D.O. in impaired waterways, meeting D.O. discharge requirements and increasing the D.O. level in the hypolimnion of lakes and reservoirs. The ECO₂ SuperOxygenation system achieves high D.O. concentrations with greater than 90% oxygen absorption efficiency at a fraction of the power requirements of conventional aeration. With this system, it is possible to pull a small sidestream from a river or lake, SuperOxygenate it and then dilute it back into the main river or lake to satisfy D.O. deficiencies without treating the entire body of water.
The ECO₂ SuperOxygenation system can be installed in a small footprint, above or below water lines or even mounted on barges which can then be moved wherever and whenever needed. The flexibility and efficiency of the ECO₂ system make it the technology of choice for meeting D.O. discharge requirements and aiding in the recovery of impaired rivers and lakes. The ECO₂ SuperOxygenation system, a simple process with no chemicals and no moving parts other than standard industrial water pumps, results in a robust, reliable, flexible, economically competitive and environmentally-friendly green technology.

Applications:

• Supplement D.O. to sustain aquatic life in impaired waterways
• Supplement D.O. in the hypolimnion layer of lakes and reservoirs to prevent hydrogen sulfide formation and the release of iron and manganese into solution
• Supplement D.O. to meet D.O. discharge requirements of point sources

Rivers and Impaired Waterways:
Dissolved oxygen impairment is most frequently identified as the cause of TMDL violations and is related to excess biological oxygen demand or nutrients from point or non-point sources. The cause of D.O. violations is usually related to low flows and/or low reaeration characteristics of rivers, since all wastewaters now receive secondary treatment. Reduction of pollutant loading, water flow augmentation in low flow situations, and artificial aeration are the methods used at present to try to meet TMDL requirements. But tertiary treatment and nutrient removal for further reduction of BOD is costly compared to direct oxygen supplementation to the river.
Using ECO₂ SuperOxygenation technology to add D.O. directly to rivers promises significant results and advantages not achievable in the past. The use of pure oxygen is more economical than conventional aeration techniques to satisfy D.O. standards of 5 mg/L or higher if the oxygen is dissolved efficiently. Such high concentrations can now be kept in solution using ECO₂ SuperOxygenation Technology and diluted into the main flow of the river without the necessity of treating the entire river. The ECO₂ system capital and operational costs are much less than the total cost for tertiary removal of BOD. In addition, much smaller side stream flows and civil works are required for SuperOxygenation than for aeration of the entire river. D.O. concentrations equivalent to air saturated D.O. can easily and economically be achieved with SuperOxygenation. Superoxygenation would provide a significant advantage to aeration by increasing river D.O. to as much as 5 to 7 mg/L without processing the entire river.

Lakes and Reservoirs:
ECO₂'s SuperOxygenation Technology is the foremost method for supplementing the hypolimnion in a lake or reservoir with D.O. to avoid anaerobic conditions and the negative effects of H2S production and Fe and Mn release, associated with it. Rather than aerating from the surface down, an ECO₂ system will pull a sidestream from the hypolimnion, oxygenate the water and then discharge it horizontally back into the hypolimnion without destratisfying the lake. Anaerobic conditions in the hypolimnion are the cause of a number of negative environmental consequences including the release of iron and manganese from the bottom sediments to the surrounding water as well as the formation of malodorous and corrosive hydrogen sulfide. These compounds degrade the aesthetic quality and treatability of drinking water. Elevated concentrations of these toxins as a result of anaerobic conditions may also impair aquatic life within the reservoir as well as tail waters released from the hypolimnion. It is critical to maintain existing stratification while supplementing dissolved oxygen into the hypolimnion to maintain water temperatures. ECO₂ allows for the existing stratification in the lake to be maintained. ECO₂'s system accomplishes this by withdrawing a sidestream from the hypolimnion, raising the dissolved oxygen and discharging the oxygenated water directly back into the hypolimnion. This method ensures that the sidestream has the same water temperature and therefore the same density as the hypolimnion ensuring residence of the oxygenated water in the hypolimnion. The thermal stratification creates a natural barrier that prevents the oxygenated water from leaving the hypolimnion, keeping it near the sediment where it is needed.

Traditional aeration systems are inefficient and waste oxygen either by undissolved oxygen bubbling to the surface or by mixing the entire water column in order to distribute dissolved oxygen. Diffusers bubble air or oxygen through the water column in hopes that a small portion dissolves and stays in the hypolimnion. The absorption efficiency is low and dependent on the depth of the lake which constantly fluctuates. Any oxygen that is dissolved outside the hypolimnion is also wasted.

Technologies that mix the entire water column to drive oxygen to the hypolimnion have to move large amounts of water using significant amounts of energy. The majority of oxygen transferred using this method does not become introduced to the hypolimnion or remain in the hypolimnion where it is needed and is therefore wasted.

Artificial destratification, caused by traditional aeration equipment, increases the temperature in the bottom waters. Higher temperatures degrade cold water fishery habitant and warm discharges from destratisfied reservoirs may negatively impact downstream fish habitats. In drinking water reservoirs, a homogenized water column precludes the optimization of raw water quality by selective depth withdrawal.

The ECO₂ System achieves an oxygen absorption efficiency of 90-95%, and since the dissolved oxygen is directly delivered to the water sediment interface, none of the oxygen is wasted. This minimizes the cost of oxygen which is the most significant line item cost in a life cycle cost analysis for an aeration system. The oxygenated water creates an ¡§aerobic cap¡¨ to the sediment, effectively preventing the production of H2S and release of iron and manganese from the sediment.

Point Sources:
As the global population continues to increase, the need for clean water will continue to increase in importance. Having recognized this fact, regulatory agencies have begun to tighten controls on point source discharges into bodies of water. Each year it seems, rules and regulations are continuing to become more stringent requiring water professionals to develop innovative and unique methods to stay in compliance. Often times, this innovation comes at a high price ¡V especially considering the addition of tertiary treatment or reverse osmosis processes to existing water treatment facilities to lower a discharge from 5 mg/L of BOD to 3 or 4 mg/L.

Certain regulatory agencies have begun to allow treatment facilities to offset their discharge with additional D.O. to offset the increased demand for D.O. in the receiving body of water. For example, if a wastewater treatment plant had a previous limit of 5 mg/L of BOD which was lowered to 3 mg/L of BOD, this plant may be allowed to continue to discharge 5 mg/L of BOD if they also ensure that the effluent has at least 2 mg/L of D.O. so that the D.O. already resident in the receiving body is not adversely impacted. The additional D.O. will assist in the natural biological activity in the receiving body to further reduce the 5 mg/L in the discharge to the desired level of 3 mg/L.

1. Savannah Harbor article August 2007
2. Savannah Harbor Re-Oxygenation Project
3. Water Quality Design Data Checklist
4. Marston Reservoir Article, Fall 2009