About a week ago, I was shown around Egret Marsh by Matt Van Ert, a Phd Biochemist and Keith McCully, the Indian River Stormwater Engineer. The purpose of this algal turf scrubber plant is to remove the algae before it ever enters the Indian River Lagoon and harvest it for a usable product. This reduces the nitrogen, phosphorus, and potassium levels that are being dumped into the lagoon. Since 2010, this plant has cleaned 10 million gallons of water coming from a large canal that drains over 9,000 acres. The water going back into the lagoon has approximately double the oxygen coming in. The large strand of algae that Matt and Keith are holding came through the pipe and then continue to grow on the 4.6 acre sloped floway.
The water that is pumped out of the canal and travels through this system flows in a thin sheet over the algae, which assimilates dissolved nutrients and traps sediment. The algae provides the structure in the water for tiny crustaceans to live in that birds feed on. The image below shows some of these creatures.
There are several types of periphytic algae growing on the floway. Periphytic algae includes cyanobacteria, diatoms, and chlorophytes and actually forms the basis of the oceanic good chain. Algae supports life and is not problematic until it grows out of control and removes oxygen from the water, causing plants and animals to die and break down, and creating bacteria that is toxic to the entire ecosystem. The most recent disaster in the Indian River Lagoon occurred in March, when oxygen levels plummeted to near zero for several hours and millions of fish died. All of this algae would enter the lagoon, if it were not for this water treatment plant.
Algae is one of the most rapidly growing plants, which is why blooms are so problematic. Yet, as a controlled, harvested crop that has not broken down lifeforms and created toxic bacteria, algae also absorbs carbon dioxide and releases oxygen. Carbon dioxide is one of the main culprits of global warming, so more of these plants around the world might help slow down climate change as well. Currently there are only two of these plants in the United States, this one and the one in Lake Okeechobee that has since been shut down. The reason for the closure of this plant was the chemical toxicity of the water in Taylor Creek, which had more than just high nitrogen and phosphorus loads, another reason why the water in Lake Okeechobee is so damaging to the Indian River Lagoon and the Caloosahatchee River.
The water then flows through a 15 acre polishing pond system before being released into the lagoon.
Some of the water that is not fit to be recycled is released into a smaller canal that feeds into a marsh area and this muck is frequently cleaned out. Muck is another huge issue in the Indian River Lagoon.
This image below shows a mountain of the algae and pond scum that has been removed. The other, usable algae is taken off site to compost.