CONSTRUCTED WETLANDS

Well-established natural treatment technology for cleaning wastewater

Waste water is cleaned by using plants to take up excess nutrients, enhanced microbial activity to decompose pollutants and kill pathogens, and sediments to trap toxic chemicals.

CONSTRUCTED WETLANDSWell-established natural treatment technology for

cleaning wastewater

Constructed wetlands for wastewater treatment offer a cost-effective solution by providing efficient treatment, thereby extending the functional life of wastewater treatment plants in the U.S. and removing pollutants from wastewater lagoons in developing countries.

Constructed wetlands bring multiple values. These include:• Near complete elimination of human pathogenic bacteria,

parasites and viruses; even recalcitrant cholera can be eliminated when anerobic ponds are coupled with constructed shallow flow wetlands.

• Ability to degrade many pharmaceuticals, endocrine disruptors, and many pesticides;

• Reduction of storm water energy;• Creation of surrogate wetland habitat for waterfowl, amphibians

and other • Wildlife; with the loss of coastal freshwater wetlands this function

is especially important.• Reducing cost of electricity for pumping water because water

movement is• Largely gravity driven; and,• Producing significant biomass for ethanol production thereby

producing fuel while reducing greenhouse gas emissions.

It is this last value, the production of biofuels from renewable biomass, that we wish to address here because constructed wetlands are a significant and unrecognized source of renewable energy.

Biomass from various wetland plants offers opportunities to develop a wide range of end products. Depending upon the plants chosen, ethanol, biodiesel, hydrogen, specialty chemicals, and energy, through direct combustion of the biomass, are some of the possibilities. Because plants need carbon dioxide to grow, the fuels and combustion options offer a carbon neutral source of clean energy.

The use of plant biomass from wastewater constructed wetlands has several significant and unique advantages over all other sources of farm-based biofuels:• There is no need for water irrigation • There is no need to add fertilizer• This plant material would not compete with food crops• Wastewater treatment wetlands typically have higher biomass yields