October 2007, Vol. 19, No.10

Small Communities

The New Biosolids Management Paradigm — Is Part 503 Too Much?

A.R. Rubin and Bob O’Dette

The management of biosolids is one of the most significant challenges facing small wastewater treatment facilities. In 1979, the U.S. Congress mandated that the U.S. Environmental Protection Agency (EPA) establish criteria for the management of municipal sludge ― that is what biosolids were called in 1979. The Feb. 19, 1993, issue of the Federal Register codified these management practices as 40 CFR 503 — Standards for Use and Disposal of Municipal Biosolids. The rule, based on the best science available at the time, primarily addressed pathogen reduction, vector attraction reduction (VAR), nutrient management, regulated metal content, and stability.

Rule requirements for VAR and pathogen reduction are met through prescribed processes. For VAR, the most common ones are aerobic and anaerobic digestion, lime stabilization to pH 12, extensive drying, and injection or incorporation on land receiver sites. The processes to significantly reduce pathogens (PSRPs) are anaerobic or aerobic digestion, drying, composting, and lime stabilization. Methods utilized to achieve the higher level of pathogen reduction ― the processes to further reduce pathogens (PFRP) ― are extended composting, heat drying and heat treatment, thermophilic digestion, irradiation, and pasteurization. These processes are all included in Part 503. Small communities typically rely on one or more of the PSRP options to ensure compliance with the rule. PFRP options often used by small communities include composting, lime stabilization and pasteurization, and heat drying, followed by land application.

EPA developed Part 503 through a comprehensive risk assessment model that examined 14 possible exposure pathways that could either influence ecosystem health or have a direct impact on human health. Part 503, when it was published in 1993, underwent one of the most rigorous risk-based evaluations of all the federal regulations to that date. The initial risk pathways were established and evaluated by scientists from EPA, academia, municipal agencies, and the private sector. The science is good, but many still view the rule’s risk evaluation, assessment, management, and reduction processes as inadequate. Skeptics say there is not enough information on the hazards to adequately assess all the cumulative risks from biosolids.

Issues remaining include comprehensive nutrient management, recordkeeping and reporting, developing trust, and an enumeration of the environmental benefits derived through biosolids programs. Since passage of Part 503, several states have established biosolids management regulations, many of which are more stringent than those contained in the federal rules. Further, counties and townships have established local ordinances regulating the land application of biosolids. Many of these rules now require provisions for developing comprehensive nutrient management programs and associated pollution prevention or best management practice programs.

Historically, Part 503 has focused more on pathogens, vectors, odor and nuisance, and regulated metals than on assessing environmental benefits. More recently, studies have examined potential consequences of biosolids management efforts on land receiver sites enriched with nutrients ― nitrogen, phosphorus, and calcium. The impacts to small communities can be severe when biosolids management efforts compete with other nutrient sources in the watershed.

Studies of soil materials throughout the southeastern United States indicate that many sites contain phosphorus levels high enough to have an impact on the immediate receiver environment. This phosphorus may exit the enriched sites through runoff or leaching losses to shallow groundwater, with subsequent discharge to surface waters. Continued application of phosphorus-containing materials to these sites may be detrimental to environmental quality.

Land-based treatment systems continue to offer small communities viable management options for the biosolids generated. Opportunities exist for small communities to leverage economies of scale by entering into environmental cooperatives with adjoining communities to address issues of mutual concern.

Small communities may wish to develop compost operations to accommodate biosolids. Compost operations can be developed using low-tech solutions to produce either a PFRP or PSRP material that could be marketed in the community. For instance, several small North Carolina communities are using lime pasteurization as a means to produce a PFRP material.

A Code of Good Practice
A comprehensive biosolids management program for any community, large or small, requires that operators develop local programs to assure local landowners, product users, local elected and appointed officials, and regulatory agency personnel that each aspect of the program receives the necessary attention. Today, emphasis is placed on management programs, such as the environmental management systems (EMS) approach used in business and industry. Ultimately, these requirements will be developed into a comprehensive code of good practice that addresses

  • product quality assurance through testing and monitoring;
  • specification of appropriate biosolids loading criteria tailored to the specific needs of each receiver site and mandatory best management practices on all sites that receive biosolids-derived products;
  • management practices that ensure records are developed and maintained appropriately;
  • management practices that ensure biosolids loads to each receiver site are applied uniformly and evenly over receiver sites by properly calibrated;
  • management practices that promote environmental quality issues;
  • development and implementation of testing programs to ensure that crops, groundwater or surface water, and soil quality are not degraded;
  • development and implementation of communication programs that supply appropriate information to all potentially affected groups;
  • integration of comprehensive, watershedwide nutrient management programs that integrate all sources of nutrients into the program;
  • third-party certification of each aspect of the comprehensive nutrient management effort and certification of the processes to produce PSRP or PFRP materials;
  • mandatory operator training, and certification and training requirements for all individuals associated with the comprehensive biosolids–nutrient management effort; and
  • integration or beneficial co-utilization of diverse byproduct streams into products that generate value-added materials from common waste materials.

Ultimately, a comprehensive code of good practices will be implemented through the industry. Programs such as EMS can be applied at the small-community level to ensure that biosolids are properly managed. The comprehensive code of good practice must be viewed as a continually evolving code to cope with the ever-changing environment in which the program operates.

Biosolids management will continue to be a challenge for small communities. The wastewater facilities are often small, and the volume of biosolids generated may not necessitate a dedicated program. Opportunities for biosolids management cooperatives may be an excellent option for small-community facilities. Regardless of the management option selected, biosolids management programs must be permitted by appropriate regulatory agencies. Wastewater system or facility operators, town and township managers, and the local officials accountable for sustaining local wastewater infrastructure must understand the permit requirements applicable in their area.

A.R. Rubin is professor emeritus of biological and agricultural engineering, at North Carolina State University (Raleigh) and a senior environmental scientist at McKim and Creed (Cary, N.C.). Bob O’Dette is assistant manager of municipal facilities at the Tennessee Water Pollution Control Department.

A.R. Rubin is professor emeritus of biological and agricultural engineering, at North Carolina State University (Raleigh) and a senior environmental scientist at McKim and Creed (Cary, N.C.). Bob O’Dette is assistant manager of municipal facilities at the Tennessee Water Pollution Control Department.