Sewage Sludge

Sewage Sludge

by Mark Dunau

Sewage sludge is what is left in a sewage treatment plant after sewage has been treated and water has been released. It is a mixture of human and industrial waste. The industry term for sewage sludge is biosolids.

Half of the American population lives within 50 miles of an ocean. In the 1980s, urban America was appalled to see its own defecation wash back on itself, spoiling American beaches. Federal legislation was enacted to outlaw dumping of sewage sludge into the ocean, and in 1992 the practice was banned from American shores by the Ocean Dumping Act.

Unfortunately, the federal government’s alternative to ocean dumping of sewage sludge has been to allow cities to spread it on American farmlands. This was accomplished not by making sewage sludge nontoxic, but by redefining what was safe for agricultural use. In 1993 the amount of heavy metals allowed in sewage sludge by the Environmental Protection Agency (EPA) was increased several hundred percent: 267 pounds of lead, 37 pounds of arsenic, 35 pounds of cadmium, and 15 pounds of mercury may be applied per acre of agricultural land. What was once defined as toxic waste by the EPA has been redefined as fertilizer so that municipalities will have an inexpensive means to dispose of sewage sludge.

The U.S. standards for sewage sludge are the most permissive in the industrial world. Although tens of thousands of synthetic chemicals may be found in sewage sludge, including polychlorinated biphenyls (PCBs) and dioxin, the EPA has no restrictions on the type or amount of synthetic chemicals that may be present in sewage sludge.

Currently, 50% of the sewage sludge of urban America is spread over the farmland of rural America. Sewage sludge is most often spread on agricultural land by agribusiness. Informed family farmers are resistant to using this cheap source of nitrogen because they see more than profit in the soil; they see their families’ futures.

The most lucid and scientific criticism of the EPA’s sewage sludge standards is the study of the Cornell Waste Management Institute, The Case for Caution. The study’s authors describe EPA’s standards for sewage sludge as nonconservative and not adequately protective. For instance, while the EPA allows the application of 35 pounds of cadmium per acre, the Cornell Waste Management Institute recommends application of less than 2 pounds. The Cornell Cooperative Extension, known as a moderate voice in agriculture, has adopted all of the recommendations of the Cornell Waste Management Institute. The Case for Caution can be obtained at http://www.cfe.cornell.edu/wmi/PDFS/LandApp.pdf.

In the long run, industrial and household toxins should be prohibited from entering the municipal waste stream. When industrial toxins are allowed to enter a municipal sewage treatment plant, it is the taxpayer who must pay for their disposal. Industry, not municipalities, should pay for the safe disposal of industrial waste.

In March 1999, the members of Northeast Organic Farmers Association of New York unanimously adopted a resolution opposing the application of sewage sludge on agricultural land. Many conventional farmers also oppose the agricultural application of sewage sludge. NOFA-NY’s organic standards prohibit the use of sewage sludge on organic farms.