biosolids.com | About Biosolids: Frequently Asked Questions

What are biosolids? Biosolids are a solid organic byproduct of purification systems that treat wastewater from U.S. homes and industry. They are created after wastewater processing and treatment leaves residuals, or solids, from communities' municipal and private wastewater treatment plants. Rich in nutrients, biosolids can be recycled beneficially and used as a natural fertilizer or soil amendment to enhance the land. The origin of the term biosolids stems from the biological processing of wastewater solids, thus the word biosolids. to top

How are biosolids used? Biosolids have a range of uses. They primarily are used as natural fertilizer to improve the quality of land for agriculture and increased crop yields, but also are employed to reclaim strip mines, improve forestland, fertilize golf courses and as organic compost in home and community gardens. to top

How are biosolids made? Locally operated wastewater treatment facilities clean and reclaim water from community sewage systems through physical, chemical and biological processes. While the treated, purified water is discharged into waterways, the solids that remain undergo further treatment to eliminate pathogens, or disease-causing organisms, reduce odor and avoid attracting animals and insects that can carry disease. These solids are treated using a combination of processes, including heat systems, digestion, lime stabilization, pasteurization and composting that convert the material into biosolids. Once treated to meet U.S. Environmental Protection Agency's (EPA) strict Part 503 requirements for pollutants and pathogens, biosolids can be beneficially used. to top

What are the benefits of biosolids? When conducted in compliance with strict state and federal regulations, biosolids recycling benefits communities with an excellent source of safe, organic nutrients. Biosolids can improve crop production, reduce soil erosion and protect water quality, provide topsoil for recreational uses, reclaim strip-mined lands, enrich forest lands and conserve landfill space. (See "Biosolids Benefits".) to top

Is there a difference between biosolids and sewage sludge? Yes. Biosolids are not sewage sludge. Sewage sludge includes untreated solids from wastewaters that remain after processing in a municipal wastewater treatment plant. Biosolids are treated to remove all, or nearly all, of the pathogens that can be found in sludge. to top

Do biosolids have an odor? Because biosolids originate in sewage, they can have an odor, but typically any odor quickly dissipates in the atmosphere. Improperly managed programs can lead to odors, creating a public nuisance for local residents (See Guide to Field Storage of Biosolids.) If the biosolids have been properly treated at the wastewater treatment facility and responsibly managed during the production of compost and fertilizer and during application to farmland, odor usually does not present a problem. The siting, design and operation of biosolids facilities now routinely provide the necessary safeguards against the release of odorous compounds. In the production of fertilizer products from biosolids, advanced technology that provides for thermal destruction of odorous compounds in a fully enclosed facility is a proven solution for controlling odors. In composting, managers successfully control odors by maintaining aerobic conditions and directing process air through scrubbers and/or biofilters in an enclosed process. During transport between these controlled facilities, odors are managed through the use of enclosed trucks. to top

Do biosolids pose a threat to human health, i.e., how safe are they? Biosolids have been used for decades, if not centuries, with no demonstrated adverse affects to human heath. The elimination of pathogens, or disease-causing organisms, is critical to safe and responsible biosolids management. The elimination and reduction of pathogens is accomplished through the use of digestion, high-temperature and stabilization processes. Additionally, soil conditions quickly kill pathogens after land application. According to an EPA-requested National Research Council Study released in 1996, biosolids that meet federal regulatory standards for treatment and land application when used in the production of food crops for human consumption represent "a negligible risk." The standards for the land application of biosolids may be found in EPA's 40 CFR Part 503 Biosolids Rule of 1993. to top

Is it safe to eat food that has been grown using biosolids? Yes. In mid-1993, at the request of EPA, the Water Science and Technology Board of the National Research Council/National Academy of Sciences (NAS) undertook an extensive review of biosolids management practices, regulatory standards and public health issues. In 1996, NAS released "Use of Reclaimed Water and Sludge in Food Crop Production." This extensive peer review concluded "the use of these materials in the production of crops for human consumption, when practiced in accordance with federal guidelines and regulations, presents negligible risk to the consumer, to crop production and to the environment." In 2000, EPA again asked NAS to review the science and methodology underlying the agency's current health and environmental standards for biosolids. The review is designed to ensure that such standards are based on the best and most current science possible, and that biosolids management policies are responsive to that science. NIOSH, a division of the U.S. Centers for Disease Control, is assisting in conducting the review. to top

Do biosolids contain toxic pollutants? A group of more than 100 pollutants are known to be potentially harmful to humans, animals and plants. EPA divides toxic pollutants into two primary categories: metals and organics. Biosolids can contain low concentrations of metals. As municipal wastewater treatment facilities and systems have improved during the last 20 years, metal concentrations in biosolids have decreased dramatically and typically are well below federal and state standards. Many of the trace metals in biosolids, including cadmium, lead, copper and zinc, can enter wastewater from industrial drains and metal pipes in homes and businesses. Some of these metals, known as micronutrients, are essential in small amounts for plant survival. Biosolids are routinely tested for metal concentrations to ensure compliance with state and federal regulations. Organic compounds, including pesticides, solvents and polychlorinated biphenyls (PCBs), can be present in biosolids in concentrations near the lowest detectable limits. Studies have found risks to be negligible. to top

Can biosolids pollute or contaminate surface and groundwater? Biosolids pose little risk to groundwater or surface water quality. As with any fertilizer, the chief groundwater concern is use of nitrogen, the application of which is regulated. Unlike commercial fertilizers, about 95 percent of the nitrogen in biosolids is present in a slow-release organic form, making biosolids less likely to cause groundwater pollution from the release of nitrates (the mobile form of nitrogen). Regulations limit the use of biosolids on agricultural land to strict agronomic loading rates, the rate that is necessary for crop growth but which minimizes passage beyond the root zone. In addition, when biosolids are applied to land with the adequate soil pH, the solubility of metals is controlled, preventing them from moving into groundwater. Most state regulations require that the soil pH be maintained at 6.0 or higher, to ensure that metals do not contaminate soil and groundwater. to top

How are biosolids regulated? EPA and state environmental agencies regulate the use of biosolids. On Feb. 19, 1993, EPA published the 40 CFR (Title 40, Code of Federal Regulations) Part 503 Biosolids Rule governing the use and disposal of municipal sewage sludge pursuant to Sections 405(d) and (e) of the Clean Water Act. (Standards for the Use or Disposal of Sewage Sludge 40 CFR 503) Part 503 requirements are based on results of a comprehensive multimedia risk assessment that began in the mid-1970s and was more extensive than any previous federal rulemaking effort for biosolids. EPA's publication, A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule, shows the many steps followed to develop the scientifically supportable, safe set of rules.
The Part 503 rule includes numerical limits for metals in biosolids; pathogen reduction standards; site restrictions; crop harvesting restrictions and monitoring; and record keeping and reporting requirements for land applied biosolids. The rule includes similar requirements for biosolids that are surface disposed or incinerated. There have been several revisions to the Part 503 Rule. EPA oversees the nation's biosolids management practices by maintaining a risk assessment capability; establishing, enforcing and revising standards; and providing tools for decision-makers at the local level. The agency generally looks to state and local government to make decisions regarding use and disposal options and for local enforcement. to top

How were the federal biosolids rules developed? The Part 503 rule is widely recognized as a risk-based rule-making effort by independent scientists to protect public health and the environment. In the development of the rule, an extensive review of university and field data was undertaken by nationally renowned scientists who are independent of EPA. to top

Are there different grades or classes of biosolids? Yes, EPA established both "Class A" and "Class B" biosolids. Class A biosolids contain no detectible levels of pathogens. Class B biosolids are treated but have detectible levels of pathogens. Different rules apply to the classes. For example, buffer requirements and public access and crop harvesting restrictions apply to Class B biosolids. to top

Can anyone apply biosolids? Yes, provided the application of biosolids on land complies with all applicable regulations. Anyone involved in this activity should be familiar with and meet both federal and local regulations. A permit can be required and care should be taken to check regulations that apply in local communities. to top

What are the federal and state biosolids restrictions on land application sites? The requirements address a number of areas. Among them:
• animals cannot be grazed on land until at least 30 days after application of biosolids;
• food crops whose harvested parts touch the biosolids/soil mixture and are above the land surface cannot be harvested until at least 14 months after land application occurs; and
• when the biosolids remain on the land's surface for four or more months before mixing into the soil, food crops with harvested parts below the land's surface cannot be harvested until at least 20 months following application. This stretches to 38 months when the biosolids remain on the land's surface less than four months before being incorporated into the soil.

Other important restrictions relate to public access. Access to land with a high potential for public exposure is restricted for one year after land application. Access is restricted for 30 days in areas with low potential exposure. to top

Are there other restrictions on public access to sites with biosolids? In general, Class A, or Exceptional Quality (EQ), biosolids used in small quantities by the general public have no requirements regarding buffer zones, crop type, crop harvesting or site access. EQ biosolids is the designation given to treated residuals that contain low levels of metals and do not attract vectors (disease-carrying animals and insects). When used in bulk, Class A biosolids are subject to buffer requirements but not to crop harvesting restrictions. In general, Class B biosolids are subject to buffer requirements, public access and crop harvesting restrictions. to top

Are state requirements more restrictive than those of the federal government? Yes, in some cases. States have the power to impose requirements that add to or make more stringent the requirements for use of biosolids when necessary to protect public health and the environment from an adverse effect of a pollutant that might be present in the sewage sludge. to top

Are there rules about where biosolids can be applied? Yes. To determine whether biosolids can be applied to a particular land site, the land applier generally performs an evaluation of the site's suitability. The evaluation examines water supplies, soil characteristics, slopes, vegetation, crop needs and the distances to surface and groundwater. Care should be taken to consult the local rules before land application occurs. to top

Whom should I contact with questions and concerns? Contact EPA or the biosolids coordinator for your state to answer questions about approved land application sites. (See links on this site.) Residents also can contact their local county conservation districts and area biosolids generators to answer specific questions about a treatment or land application procedure. to top

What will it mean for a wastewater treatment plant, biosolids manager or land applier to agree to an Environmental Management System (EMS) for biosolids? The National Biosolids Partnership (NBP) is now developing a voluntary EMS for biosolids. The NBP consists of members from the Association of Metropolitan Sewerage Agencies, the Water Environment Federation, EPA and other stakeholders, including the general public. Those facilities that pledge to follow the EMS agree to implement community-friendly practices in addition to being in compliance with applicable state and federal regulations. Community-friendly practices refer to the control of odor, traffic, noise and dust, as well as nutrient management. Those who pledge to follow the EMS are subject to audit by impartial independent third parties. to top

How are biosolids viewed in the scientific community? During the development of the 40 CFR Part 503 Rule for Biosolids published in 1993, independent scientists worldwide reviewed extensive data on the safety and environmental effects of biosolids use and disposal. The data includes findings from thousands of field trials and laboratory experiments conducted over previous decades. From this data, as well as current and ongoing research, scientists have reached overwhelming agreement that the beneficial use of biosolids, when conducted in accordance with strict federal and state regulations, poses negligible risk to the public and the environment. to top

How are biosolids transported? Biosolids generally are transported locally in enclosed trucks to control odors and noise. Upon arriving at a land application site, they are directly applied to the land using tractors, tank wagons, irrigation systems or special application vehicles. . to top

Are biosolids used in other countries? Biosolids are used widely in Europe and China, as well as in other countries. For the past 40 years many countries have actively participated in conducting field trials to determine the safety and environmental soundness of responsible biosolids management practices. to top

How long have biosolids been in use? Recycling biosolids is not a new management concept. For thousands of years, Chinese society returned sewage to farmland in an effort to maintain soil. In parts of Europe and elsewhere, biosolids have been applied on agricultural land for a century and longer. In the United States, biosolids recycling is as old as farm reclamation, even as old as power generation from wind, solar and hydro-power sources. Today, thousands of municipalities in all 50 states successfully recycle their biosolids.

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Sources Include:

EPA Office of Water Management

National Biosolids Partnership

Water Environment Federation