For many years, dredging has been the solution for dying ponds and rivers. Dredging removes sediment, some excess nutrients, pollutants and organic matter. By increasing the depth in this way, weed growth is discouraged, water temperature lowered and oxygen levels increased. Though dredging can help in these ways, it only solves part of the problem, and causes some others.

Mechanically removing sediment is extremely disruptive to the aquatic ecosystem. Removing sediment and organic matter also removes the plants and animals of the bottom community, which form the basis of life for higher animals. Further, dredging does not often consider what the natural contours of a waterway should be. Near-shore areas are deepened, eliminating shallow habitats, spawning and rearing grounds, changing natural flow patterns and precluding recreational uses such as swimming. The sudden increase in turbidity further degrades water quality, stressing fish and other organisms, sometimes fatally. The changes in light patterns throw off reproductive cycles. It can take weeks for the water to settle down, and in the end, the system is completely unbalanced.

Using nature to heal itself is a gentle yet powerful way to treat a disturbed ecosystem. Water quality problems are often due to a combination of factors and are manifested in a number of ways. Poor water quality does not end with sludge removal. The water column may be polluted by industrial effluent containing everything from table salt to cyanide. Runoff and sewer discharge may contain fertilizer, pesticides, road salt, oil and gas. It is the combination of these pollutants in addition to the detriments of sludge that leads to a dying water.

Bacteria have evolved for millions of years, in any number of habitats, with an appetite for a surprising number of compounds. Indeed, one of their roles in nature is to turn complex substances, no longer usable to other life forms, back into simple, usable compounds.

Introducing bacteria in large quantities into a polluted system merely transplants nature's engineering to the right place at the right time. Bacteria will degrade sludge and pollutants dissolved in the water column, turning them into carbon dioxide, water and more bacteria. As the system returns to normal, the water becomes clear, the sludge disappears, and nature takes over, restabilizing the topography and ecology. The bacteria themselves will die back to a normal population once their food source is diminished.

Biotechnology is both more complete as a treatment and far less expensive than mechanical treatment. Wet dredging has been estimated to cost approximately $40,000 to $100,000 per acre-foot of sludge, while Alken Clear-Flo® products cost, depending on the level of contamination, costs $1500 to $5000 for each acre-ft of organic sludge. This represents a savings of more than 80% of the cost of wet dredging!

In some cases, additional equipment, such as aerators and bioreactors (ie the Alken® Bioactivator 2000), is needed, however, total cost is still well below that of mechanical dredging. Bacterial treatment avoids unsightly machinery, ramp building and mounds of sludge. It also avoids creating a second environmental problem: disposing of the sludge. There are few limitations: Bacteria cannot degrade dirt, rock, sand or other inorganic substances. Alken Clear-Flo® cannot survive in fluctuating extremes of temperature and pH or when high levels of metals or biocides are present. Otherwise, there are few limitations.