Spraying sewage onto forests: new solution to waste treatment
Clayton County, Ga. — With the flip of a switch in November, some 17,000 sprinklers will begin spewing out sewage. Everyday, about 19 million gallons of odorless, semitreated sewage will be sprayed on a 3,500-acre pine forest here, just south of Atlanta.
Because of the spraying, the trees will grow faster, underground water tables will be replenished, and purified water, filtered through the ground, will flow into a local creek from which the county will draw its drinking water.
More important, the whole system, including land purchase and sprinkler installation, costs no more than a traditional sewage treatment plant -- and six times less to operate.
With proposed major cuts in federal funding for sewage treatment and the prospect of higher water bills in the future, water resource experts say that using forests, fields, or croplands for seep-through sewage cleanup could help hold down local water bills in many places.
Clayton County would have had to restrict growth unless it expanded its treatment system to meet federal water standards. The county is adding the alternative waste treatment to its existing program, but the spraying method can also be used as the primary treatment if a holding pond is used to deodorize the waste.
Many urban areas could also benefit by piping water to nearby rural areas for such treatment at costs below traditional methods, says Wade Nutter, former chairman of the American Clean Water Association and designer of the type of system used in Clayton county.
President Reagan wants to stop federal funding for expanding sewage systems to serve new growth in communities, concentrating instead on the huge backlog of already developed areas needing initial or improved sewers. Though some local officials in fastgrowth states such as Florida have opposed such cutbacks, the National Association of counties calls the Reagan plan "logical." Industries and homeowners in newly developing parts of a community should pay for their sewer facilities, says an association official.
Even without federal cutbacks, many communities face potentially much higher water bills in the years ahead, because of the high cost of bringing their treatment plants up to federal standards. The General Accounting Office said in a report last year that between 50 and 75 percent of the nation's sewage treatment plants were not meeting federal standards, despite $25 billion in federal funds for local sewage programs.
The Environmental Protection Agency (EPA), however, is reviewing water quality standards to see if they should be relaxed.
Regardless of where the burden falls, various water resources experts believe alternative sewage treatment systems, such as the one in Clayton County, will be getting a closer look.
Some 700 communities have begun using such alternatives, many of them in the past several years, says the EPA, which has given financial incentives for their use.
The town of Greenville, Maine, treats sewage on acres of Christmas trees.Muskegon, Mich., uses some 5,000 acres of cornfields to treat sewage part of the year. Lubbock, Texas, has for many years treated waste using some nearby cotton fields. And the cotton yields have outpaced those of many of the neigboring fields, says Ed Hopkins, researcher with the American Clean Water Association.
But many local officials are still unfamiliar or not confident about such alternatives. There are concerns about odor and mess, and some poorly designed alternative systems cna have both, Mr. Hopkins says.
But partial testing shows the Clayton County system has neither, says Mr. Nutter, an associate professor in the School of Forest Resources at the University of Georgia. "I wouldn't hesitate to go to the stream where the ground water comes into the stream and take a cup and drink it."
The waste contains nitrogen and phosphorus, which aid crop and tree growth. Nutter says that in tests on a similar but smaller system in northern Georgia, tree growth was 10 to 20 percent greater than on nonsewage treated trees.
There are drawbacks, however.The alternative treatment requires land, though not necessarily all in one chunk, says Nutter. And metal concentrations in the waste can harm crops or trees if not pretreated by traditional sewage plants or holding ponds.
Communities downstream from Clayton County now get cleaner water -- but far less of it, as most of the water the county once disposed of in streams it now draws off to meet its own needs.