CASE STUDY: CLEAN-FLO inversion oxygenation reverses eutrophication - improves raw drinking

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1 CASE STUDY: CLEAN-FLO inversion oxygenation reverses eutrophication - improves raw drinking water The Challenge Toa Vaca dam was built in 1972 to create a 247 acre raw drinking water reservoir in Puerto Rico. The maximum depth is about 174 feet. The intake tower for the water treatment plant has 6 intake gates, which are each about 30 feet apart. When built, it had a life expectancy of 300 years; however by 2009 it was highly eutrophic and fish kills were common. The plant was only able to use water from the top 2 gates without significantly increasing treatment costs. This created a significant problem during the dry season when reservoir levels typically drop below the first 2 gates. In general terms, reservoirs have limited vertical mixing, and when combined with a high residence time and nutrients like nitrogen and phosphorous, both blue green algae and weeds find the perfect environment to dominate. Blue Green algae has no natural predators and can move up and down the water column, this together with their ability to produce energy through photosynthesis provides them with an important competitive advantage over other algae species. The treatment of raw water coming from a eutrophic reservoir is a real challenge. Oxygen depleted zones at the bottom of the reservoir cause the migration of metals like manganese and iron and nuisance gases like hydrogen sulfide and ammonia to the water column. Once at the drinking water plant, this water requires an increase of chlorine and lime dosing. This leads to an increase in disinfection by products which are carcinogenic. The Solution CLEAN-FLO designed a laminar flow oxygenation system for the reservoir and a treatment program for bio-augmentation. The system was installed in The bio-augmentation products were added approximately 4 months later. Our system consisted of 14 diffusers and 35,000 feet of airline. A sampling program was established every two weeks in order to closely monitor the restoration process. Water quality parameters were analyzed at diffusers three (3), nine (9) and fourteen (14), at three different depths (surface, half depth and three foot from bottom) including: dissolved oxygen, oxidation reduction potential, hydrogen sulfide, nitrogen, phosphate, chlorophyll a, and manganese. During the startup of the diffusers a remote monitoring buoy was installed and operated in order to ensure that the emission of hydrogen sulfide gas was performed in a controlled way. During the first year the water level dropped over 70 feet due to drought. The diffusers are more efficient with depth, so the reduction in depth significantly affected the rate of oxygenation of the entire water column. As the depth increased, the pace of restoration improved. The Results The benefits of restoring Toa Vaca reservoir are several and verifiable: Treatment plant cost reduction ( 25-35%) Reduction of sludge production (35-40%)

2 Better taste and color of drinking water (no yellow water) Reduction of disinfection byproducts (TTHM) Reduced impact of water scarcity (rationing) Increased biodiversity No fish kills, increased fish catching Improved water infrastructure for a sustainable economic development These 3 graphs show the reduction in total phosphorus, total nitrogen, and manganese at the bottom of the reservoir after the aeration system was started. Since the system was started, raw water quality is more consistent which makes the treatment plant more efficient. Customers are expressing their satisfaction for the better taste and odor of the water at the tap.

3 CASE STUDY: Inversion oxygenation and bioaugmentation quickly reduces organic sediments The Challenge Lake Apopka is a 30,888 acre hyper-eutrophic lake located in central Florida. Once known for fantastic fishing, the lake had 28 fishing camps located around it. Decades of fertilizer and chemical use in adjoining parcels have contributed excessive nutrient inputs that have devastated the aquatic ecosystem and have transitioned the lake from a clear macrophyte-dominated system to a turbid phytoplanktondominated system. Large quantities of organic sediment have accumulated throughout the lake bottom, destroying fishing and ultimately ending the operation of all the fishing camps. The Solution The State of Florida contracted our distributor Allied Group for implementing our inversion oxygenation and bio-augmentation in a 250 acre pilot area. The system was installed in August Prior to installation, comprehensive baseline water and sediment sampling was undertaken in May 2015, and then followed up with monthly sampling once the system was started. In December 2015, after only 4 months of operation, the data was gathered and analyzed by an independent consultant to determine if progress was being made. The Results There is no separating barrier between the pilot area and the rest of the lake, so constant mixing occurs. Even with this mixing, the results showed a 12.5% decrease in blue green algae, increased water column depth and significantly reduced water column ammonia, sediment phosphorous and organic matter. The following photos show the water behind a boat before the system was installed and 4 months later. The contour maps shown below represent the increase in water depth that has occurred between May and December. You will see an increase in depth where the muck has been consumed by the microbes. Each line in these scans represents an increase of one foot in depth from the surface of the lake with the dark blue being the deepest points in the treatment area. The scale at the right shows the feet depth associated with each color. In December, we see some areas that are five feet or deeper forming as well as expansion of the 2, 3 and 4 foot depths.

4 The maps below show the changes from red (dense vegetation growth) to blue (no vegetation growth) after 4 months. Additionally the table below the maps quantifies the changes in aquatic vegetation biovolume. There has been a substantial reduction in the highest percent cover categories (60-80%) from May to December of This is due to the ability of the laminar flow aeration system to affect the sediment pore water chemistry and drive the denitrification process which limits sediment nutrients (such as ammonia) to many rooted macrophytes % Aquatic Plant BioVolume 0%-5% 5%-20% 20%-40% 40%-60% 60%-80% >80% May 2015 December 2015 Net Loss or Gain 26.09% 8.69% 12.64% 17.76% 19.34% 15.48% 85.93% 10.87% 1.29% 0.99% 0.55% 0.37% 59.84% 2.18% (11.35%) (16.77%) (18.79%) (15.11%) Overall the project has been a tremendous success to date. The amount of visual fish activity in the treatment has increased substantially, and it will only get better with more time.

5 Here is an aerial photo of Lake Apopka showing the diffuser boils on the surface of the water.