in northern Alabama, a rapidly growing community needed more housing
but couldnt support it. The problem: There was no municipal sewer
system, and poor soil drainage ruled out drainfields. In a demonstration
project carried out in cooperation with the Joe Wheeler Electric Membership
Corporation and the state of Alabama, TVA designed a decentralized wetlands
wastewater-treatment system that provides low-cost sewage treatment
and requires minimal maintenance.
treatment systems are an environmentally friendly alternative to conventional
chemical and pump methods. Theyre also economical to build; they
can cost 50 to 90 percent less than traditional wastewater-treatment
systems. Custom-designed for specific circumstances, they can serve
one house or many, a small livestock operation or a large industry.
TVA owns and operates one of the most sophisticated constructed-wetlands
research facilities in the world. The agency has patented an innovative
reciprocating wetlands system in which a series of adjacent water cells
are alternately drained and refilled on a recurring basis. Water drained
from one cell is used to refill the next, a process that efficiently
removes wastewater pollutants by means of the presence (or absence)
TVA operates 20 passive wetlands systems at its fossil plants and reclaimed
coal mines that can treat over 40 million gallons of water per day.
And its incorporating this technology into new ammoniated-wastewater
treatment systems, which eliminate the ammonia compounds resulting from
the fossil plants installation of new air-pollution controls.
These wetlands systems have revolutionized the treatment of acid drainage
and other discharges associated with the coal and electric-utility industries.