The SDOX® unit used on Lake Brittany had a capacity of 840 pounds DO/day, which is nearly 6 times larger than the unit used previously in Lake Atalanta. Lake Brittany was oxygenated from a dam (not flow through) at a depth of 45 feet.

Performance

First, let’s take a look at the results from the installation of the SDOX® system at Lake Atalanta in Rogers, AR.

Figure 1 shows the temperature profile of the lake before and after oxygenation. Clearly, the thermocline remains intact. An interesting lesson from this deployment was that the data also shows an increase in temperature in the zone where oxygen was injected. For this test, source water was taken from near the shore, not from the hypolimnion, so warmer water was injected into the cold hypolimnion. This problem was corrected in subsequent deployments.

Figure 1. Depth profile of temperature in Lake Atalanta, AR in oxygenation zone before and after SDOX® injection.

Figure 2 shows the DO profile within the hypolimnion both before and after injection. A small increase in DO can be seen at a depth of 14 to 26 feet. The DO rise is small, but the unit only operated for two hours and was very small in capacity.

Figure 2. Depth profile of DO in Lake Atalanta, AR in oxygenation zone before and after SDOX® injection.

Figure 3 shows a top-view of the oxygen injection to illustrate how broadly dissolved oxygen was distributed with this small SDOX® unit. All water had a DO of less than 0.5 mg/L at the depth of 20 feet shown in the figure. The single injection site was at 25 ft on the x-axis and 0 ft on the y-axis. Figure 3 indicates that oxygen was distributed at least 200 feet from the site of injection in a two hour time period.

Figure 3. Post-oxygenation top-view of DO distribution at a depth of 20 feet in the hypolimnion of Lake Atalanta, AR.

Now we will look at the results from the installation of the SDOX® system at Lake Brittany in Bella Vista, AR.

Figure 4 shows the location of the SDOX® unit and the buoy locations where temperature and DO were collected at depth intervals of 3 feet. Buoy 9 is approximately 750 feet from the injection site. The SDOX® was operated for 5 consecutive days and then turned off. Temperature and DO profiles were collected at each buoy location prior to injection and day injection began, 2 days into treatment, 5 days into treatment, 3 days after injection ended, 8 days after injection ended, and 16 days after injection ended.

Figure 4. Location of buoys where temperature and DO profiles were collected during oxygen injection into Lake Brittany, AR.

Figure 5 shows the temperature profile at buoy 6 in the center of the oxygen injection area. This data indicates that the thermocline was left intact during SDOX® injection. Visual evidence from a boat also indicated no destratification occurred and no bubbles rose to the surface of the lake.

Figure 5. Temperature profile at center buoy 6.

Figure 6 shows the DO profile at buoy 9, the farthest point from the injection site. The data indicates most of the hypolimnion reached a DO of at least 4 mg/L after 5 days of injection.

Figure 6. DO profile at buoy 9 the farthest location measured from SDOX® injection site.

Figure 7 shows the DO profile at buoy 6 near the center of the treatment area and this location indicates all of the hypolimnion was oxygenated to at least 4 mg/L.

Figure 7. DO profile at buoy 6 in the center of treatment area.

Figure 8 shows a top view of the DO concentration (by color) at three depths throughout the hypolimnion after 5 days of SDOX® injection. Data collected at the buoy marker sites is indicated within 700 ft y-axis from injection site and +/- 180 ft from x-axis origin. This data indicates that the DO plume created in the hypolimnion by the SDOX® injection extends far beyond the boundaries of the buoy locations. A finite difference approximation technique was used to estimate the total extent of high DO plume formation. Estimates indicate that after 5 days, the DO plume extends 900 ft from injection site. The plume continues to build until the SDOX® unit was shut-off (see figures 6 and 7) and the DO plume exceeding 3 mg/L extends to near the edge of the hypolimnion in figure 8. This test indicates that the smaller scale SDOX® unit should easily be able to oxygenate the hypolimnion of Lake Brittany after several more days of operation.

Figure 8. Top-view DO surface plot after 5 days injection using finite-difference extrapolation of buoy data over lake area at depths of 30, 36 and 42 feet after 5 days of treatment. Injection site was at x-axis of 0 and y-axis of 0.

Conclusions

BlueInGreen’s gas delivery technology is the most cost-efficient, flexible and effective solution for most ecological restoration uses. Critical data collected from both the Lake Atalanta project and the Lake Brittany project clearly illustrates the superior capabilities of BlueInGreen’s SDOX® technology.

The benefits of SDOX® are summarized as follows:

• Cost effective DO delivery to warm or cold shallow water bodies
• Automated control of the DO delivery rate for most efficient operation
• Targeting of DO addition to a specific layer in the hypolimnion without mixing the temperature-stratified layers above
• Addition of DO with minimal disturbance of sediments at the bottom of the lake
• Targeting of optimum DO conditions for remediation, fish, and other aquatic species
• Promotion of a shift to efficient and low-odor aerobic bacterial digestion of excess dissolved organics
• Reduced dissolved metals via oxidation and precipitation