How do these water problems begin?
Industrial, commercial and residential development within watersheds increases yearly, and many of our lakes and rivers have been subjected to ever-increasing loads of nutrients, sediments, industrial pollutants, and raw sewage. The result is decreased water quality. Increased nutrient loadings are most commonly due to excessive use of fertilizers, malfunctioning sewage systems, industrial contamination and improper waste disposal within the watershed. As development continues, the amount of total hard surfaced area, such as roads and buildings, also increases; therefore, the volume and velocity of the water moving through the watershed into surface waters is increased. This run-off erodes soils and transports organic materials and nutrients from surface soils.
The elevated nutrient loadings that find their way into rivers, streams, lakes and ponds cause many environmental problems. These include: algae blooms, proliferation of unrooted aquatic plants, low Dissolved Oxygen levels, increased water temperature, unpleasant odor, increased coliform levels, stunted fish populations and fish kills when the Dissolved Oxygen reaches zero.
Healthy water bodies have a natural capacity to clean themselves. Every pond, lake and river is an individual or inter-connected ecosystem, with a food chain of organisms that assimilate the incoming nutrients. The food chain moves nutrients up from the simplest bacteria, to healthy plants, fish, and bird life. This natural system works very well without any man made system to improve water quality, keeping the ecosystem in balance until excessive human waste overwhelms the ability of the ecosystem to assimilate the nutrients.
Why do you not recommend adding chemicals to eutrophic water?
Chemical cleaning solutions kill weeds and algae, and the dying vegetation sinks to the bottom of the water-body where it decomposes. As the vegetation decays, nutrients in the plants are released back to the water column and become nutrients for the next weed growth or algae bloom. At the same time, decaying vegetation uses up the oxygen at the bottom, creating an anoxic zone. The dead mass of vegetation accumulates on the bottom of the lake adding to the mass of organic sediments already there.
If oxygen is present at the bottom, the accumulating organic sediments begin to decompose aerobically. This organic material serves as food for bacteria and other aerobic organisms that live in the substrate including insect larvae and worms. These aerobic organisms require and consume Dissolved Oxygen as they consume the organic sediments. As sediments and biological activity increase, Dissolved Oxygen levels are depleted. Low or no Dissolved Oxygen conditions can occur rapidly, wiping out these aerobic organisms which slows the breakdown of the organic sediments. Next begins the increased growth of anaerobic bacteria, the bacteria that thrive in low or no Dissolved Oxygen.
Anaerobic digestion of the organic sediments releases toxic green house gases into the water and atmosphere that further disrupt the food chain. Anaerobic digestion of lake sediments is a much slower process than aerobic digestion. Aerobic digestion can result in the control or reduction of organic sediment levels, whereas slow anaerobic digestion usually allows organic sediment levels to increase while releasing green house gases. During anaerobic digestion, bacterial enzymes and lack of oxygen make the nutrients on the bottom sediment soluble. These nutrients return to the water column and are available to support new weed and algae growth (i.e. water hyacinth, azolla, ect.).
Thus, chemical cleaning causes worse anaerobic conditions on the lake bottom which has a crippling effect on the food chain and the ecosystem.
Why aerobic bio-remediation?
To restore a water body to its original pristine condition, we must restore the natural processes that allow it to assimilate the nutrient load that it receives. We must supplement the natural assimilation of the nutrient load as it exists until the aquatic environment can sustain itself.
The natural assimilation of nutrients in an aquatic ecosystem begins to breakdown when these natural processes are limited or eliminated by low oxygen levels. Aerobic organisms are much more efficient at consuming organic material than anaerobic organisms. Aerobic organisms feed on organic materials contained in the sediments and assimilate these nutrients into increased body mass and reproduction. Aerobically absorbed nutrients become part of the food chain which moves up the chain and often out of the water.
By maintaining aerobic conditions at the bottom and throughout the water body, the food chain will improve in quantity and quality. Maintaining the aerobic environment prevents the accumulation of organic sediments. To the point - aerobic conditions at the bottom benefit all aspects of the aquatic environment.