Promoting Safer Biosolid/Sludge Land Application

Promoting best management practices (BMPs) for the land application of biosolids—also known as sludge--will lessen water pollution and safeguard public health. However, while some BMPs have been developed for nutrients, others need to be developed once the full range of constituents in sludge are determined. The designation of proper management guidelines and responsibilities for safe land application of biosolids can translate into improved environmental quality.

In response to the Clean Water Act, Federal, State and local governments have built thousands of sewage treatment and collection facilities. Today over 16,000 sewage treatment facilities serve nearly 190 million Americans (72% percent of the U.S. population—not counting those with decentralized septic and wastewater systems). In addition, these sewage treatment and collection facilities serve thousands of industrial and commercial establishments.

Roughly eight million dry metric tons of biosolids are annually produced or about 70 pounds per person per year. About 54 percent of these biosolids are land applied as fertilizer or as soil conditioner.

Biosolids range from 70 percent to greater than 98 percent water content. The dry matter in biosolids consists mostly of inert minerals (i.e., sand and silica) or biological materials comprised of fat, protein, fiber and carbohydrates. Biosolids also contain trace amounts of heavy metals and organic chemicals. And, biosolids contain varying levels of metals, pathogenic organisms, vector (e.g., insects and rodents) attractants and odor-causing substances that may be harmful. These metals, organic chemicals and pathogens can pose a threat to human health unless the biosolids are sufficiently processed and properly managed.

Part 503 Biosolid Rule allows land application (spreading) of sewage sludge (also known as sludge) as fertilizer or to condition the soil. The passage of the Clean Water Act of 1972 helped ensure that municipal wastewater was treated. In 1988, the Ocean Dumping Ban Act was enacted amending the 1972 Clean Water Act. The ban prohibited all dumping of sewage sludge and industrial waste into the ocean after 1991, leaving three main options (each with limitations) to dispose of wastewater and sludge: landfilling, incineration, and land-spreading. The EPA has focused on promoting the use of sludge for land application. In 1993, the EPA published the 503 Sludge Rule setting standards for the use or disposal of sewage

The Concern with Biosolid Land Application

The EPA’s standards have generated controversy in the scientific and agricultural communities, as well as with the general public. Although the 503 Sludge Rule establishes minimum quality standards for biosolids to be land applied, many citizens and scientists question the adequacy of these standards. Some have also proposed more stringent standards, additional source separation and greater pretreatment of contaminants. Various scientists expressed concerns about the effects on humans from contaminants concentrated in the sludge during treatment. Numerous citizens that either work with, or live near, sludge have voiced these same concerns.

Several years ago the EPA Inspector General found: “EPA does not have an effective program for ensuring compliance with the land application requirements of the 503 rules. …While EPA promotes land application, they cannot ensure the public that current land application practices are protective of human health and the environment.”

National Academies Study

In the last few years the National Science Foundation has been exploring information on the land application of sludge and evaluating the methods used by the U.S. EPA to assess risks from chemical pollutants and pathogens in sludge.

The National Academies in 2002 released a paper called, “Biosolids Applied to Land: Advancing Standards and Practices” in which their overarching recommendations were:

There is uncertainty about the potential adverse human health effects from exposure to biosolids. To assure the public and protect public health, there is a need to update the scientific basis of the 503 rule. The committee identified several data gaps and issues in management practices that should be addressed including: a lack of exposure and health information on exposed populations; reliance on outdated risk-assessment methods; reliance on outdated characterization of sewage sludges; inadequate programs to ensure compliance with biosolids regulation; and lack of resources devoted to EPA’s biosolids program.

Specifically, they are looking to:

1. Review the risk-assessment methods and data used to establish concentration limits for chemical pollutants in biosolids to determine whether they are the most appropriate approaches. The committee will also consider the NRC's previous (1996) review and determine whether that report's recommendations have been appropriately addressed. Issues to consider include: (a) how the relevant chemical pollutants were identified; (b) whether all relevant exposure pathways were identified; (c) whether exposure analyses, particularly from indirect exposures, are realistic; (d) whether the default assumptions used in the risk assessments are appropriate; and (e) whether the calculations used to set pollutant limits are appropriate.

2. Review the current standards for pathogen elimination in sludge and their adequacy for protecting public health. The committee will consider: (a) whether all appropriate pathogens were considered in establishing the standards; (b) whether enough information on infectious dose and environmental persistence exists to support current control approaches for pathogens; (c) risks from exposure to pathogens found in Class B sludge; and (d) new approaches for assessing risks to human health from pathogens in sludge.

3. Explore whether approaches for conducting pathogen risk-assessment can be integrated with those for chemical risk-assessment. If appropriate, the committee will recommend approaches for integrating pathogen and chemical pollutant risk-assessments.

Land Application in Virginia

Numerous jurisdictions in Virginia and elsewhere have questioned the practice of applying biosolids to farmland and other property. Several years ago, Land Application of Biosolids in Virginia: A Study Prepared for the Virginia Department of Health, November 1997, by the University of Virginia Institute for Environmental Negotiation cites the needs of local governments for biosolid application ordinances. The following quotes below are generic to the rest of the country’s questions:

•...Generally, county officials expressed a desire for greater information and understanding of the program, in order to increase local capability for responding to complaints, as well as having more visible and accessible “field presence.”

• Acceptance of biosolids application as an environmentally positive method of recycling depends upon public confidence that the program is properly regulated and managed. That is, citizens must feel confident that the rules are properly followed by all parties participating in the biosolids generation, application, and utilization.

Because of the possible health and safety implications if land applications of biosolids are improperly performed, some localities have either banned the practice, or are developing stricter regulations. However, in Virginia the courts have severely limited the ability of local governments to address problems and prohibit bans. Also, the application of biosolids in areas where some people have fragile immune systems is being questioned. Incidents triggered either by odor or fish kills have aroused the concern of citizens and scientists as to whether there is adequate protection for the environment or for public health.

In conclusion safe application of biosolids requires assertive pretreatment pollution prevention, adequate monitoring testing, soil surveys, screening of the application area so as to safeguard contamination to water resources and other measures to insure that sludge does not impact public health or the environment. The debate will continue as to how serious are the risks in the land applications of biosolids.