Why Aquatic Plants Are Used to Treat Wastewater

Traditional methods of treating sewage wastewater are quite expensive. Traditional treatment involves two phases. The first phase removes inorganic materials, settles suspended materials, and uses anaerobic microorganisms to digest nutrients from the water. The second phase uses large bulky tanks and treatment filters to clarify the water to make it safe for human use. This wastewater treatment method can cost millions of dollars to construct and to keep in operation. An alternative to the secondary stage of sewage treatment plants is using manmade wetlands. The aquatic plants that live in the wetlands naturally filter the water and provide a habitat for migratory waterfowl, fish, turtles, frogs, and other species of wildlife.

Why Aquatic Plants?

• In the wetland method of sewage treatment plants play a crucial part in cleaning the water and making it safe for humans to use. The types of plants that live in wetlands absorb nitrates that are present in wastewater. Living in their roots are helpful bacteria, algae, fungi, and other microorganisms that are responsible for carbon dioxide/oxygen exchange, ammonium/nitrate exchange, and phosphate removal. Even the soil of the wetlands absorbs heavy metals and other materials after they settle to the bottom of the standing water.

Natural Water Filtration

• Wetlands provide a natural transitional barrier between land and water. Much like the filtration tanks in sewage treatment facilities, the plants and soil in this barrier remove harmful metals and chemicals from the water before it moves out into a lake or ocean.

  The aquatic plants that naturally occur as water filters in wetlands are also used to filter wastewater. These plants are bulrushes, cattails, duckweed, and water hyacinths. Their roots take up nitrogen and heavy metals which are absorbed into their stems and leaves. The roots also promote the growth of beneficial microorganisms that consume nutrients that can be toxic to people, such as ammonium and certain phosphates. The microorganisms then release nitrates and oxygen into the water. Plants consume the nitrates, and fish and other aquatic animals use the oxygen to breathe.

Are Man-Made Wetlands Good For Plants?

• Certain plants stand up better to filtering than others, but for the most part the plants listed here happily live out their entire life spans. They are not negatively affected by being used to filter wastewater. When the plants naturally die off their replacement is still much cheaper than it is to replace and keep filtering tanks in proper working condition.

Other Uses

• Aquatic plants also filter other types of polluted waters. Man-made wetlands provide a living barrier that prevents poisonous run-off from getting into oceans, lakes, rivers, and streams. These waste waters include storm water run-off, agricultural waste water, coal mine drainage, petroleum refinery wastes, compost and land fill leachates, and fish pond discharges. Aquatic plants also can filter pretreated industrial waste waters from paper mills, textile mills, and seafood processing plants.

Benefits For Wildlife

• These man-made wetlands not only make our water safe, they also create a beautiful ecosystem for wildlife to live and thrive in. Many habitats for water fowl, turtles, fishes, and amphibians have been reclaimed by creating wetlands in areas that were once blighted by urban decay or garbage dumps. These wetlands save communities money and provide nature preserves. These parks give people a place to sit and bird-watch or enjoy a picnic. Migratory birds especially love this new terraforming development and have made these new wetlands common stops on their travels around the globe.