A controversy that developed last week over a plan to fertilize Antelope Valley farmland with Los Angeles sewage sludge highlights a growing reliance across the country on disposing of sludge by applying it to land.
Although there is a stigma attached to sludge, and its use as fertilizer raises environmental concerns, the idea is hardly new and is growing in popularity.
For the Record
Los Angeles Times Tuesday March 27, 1990 Valley Edition Metro Part B Page 4 Column 3 Zones Desk 2 inches; 37 words Type of Material: Correction
Sludge disposal--A March 18 story in The Times on disposal of sewage sludge incorrectly stated that in California, 45% of the sludge is put in landfills, 25% is spread on farmlands, and 21% is incinerated. In fact, those estimates are for sludge disposal nationwide.
Using sludge to nourish soil and repair scarred land is regarded by many environmental officials and advocacy groups as the wave of the future, and it is the cornerstone of the Environmental Protection Agency's policy of promoting "beneficial reuse" of sludge.
Although land application is viewed as vastly superior to the old standbys--dumping it in the ocean or landfills--most experts believe the technique is inadequately controlled under current environmental rules.
The EPA has proposed broadening and strengthening its sludge regulations to reduce risks, including pollution of soil and ground water by toxic metals and nitrates, the absorbing of metals into crop roots and the presence of disease-producing organisms in sludge. The rules, which could take effect next year, would set strict limits for 28 toxic substances and for pathogens.
EPA officials and environmentalists said they knew of no documented cases of human illness from land application of sludge. Nonetheless, the new regulations are needed, in part, because of the growing popularity of the option, they said.
There's "a veritable explosion of land application all over the country," said Dr. Douglas N. Rader, a senior scientist with the Environmental Defense Fund.
"We think that land application is the way to go," said Jessica Landman, a senior project attorney with the Natural Resources Defense Fund in Washington, D.C. But "it has to be land application of sludge that is . . . free of . . . harmful levels of toxics."
Sludge is the mud-like residue made of the solids left by sewage treatment. The best sludge is not much different than the steer manure prized by weekend gardeners. But sludge also reflects the local industrial base, containing traces of cadmium, arsenic, mercury and other harmful substances from industrial discharges and street runoff. Those compounds slosh around in waste water and then are concentrated in the sludge.
