United States Environmental Protection Agency Office of Water Washington, D.C. EPA 832-F-00-064 September 2000 &EPA Biosolids Technology Fact Sheet Land Application of Biosolids DESCRIPTION Biosolids are primarily organic materials produced during wastewater treatment which may be put to beneficial use. An example of such use is the addition of biosolids to soil to supply nutrients and replenish soil organic matter. This is known as land application. Biosolids can be used on agricultural land, forests, rangelands, or on disturbed land in need of reclamation. Recycling biosolids through land application serves several purposes. It improves soil properties, such as texture and water holding capacity, which make conditions more favorable for root growth and increases the drought tolerance of vegetation. Biosolids application also supplies nutrients essential for plant growth, including nitrogen and phosphorous, as well as some essential micro nutrients such as nickel, zinc, and copper. Biosolids can also serve as an alternative or substitute for expensive chemical fertilizers. The nutrients in the biosolids offer several advantages over those in inorganic fertilizers because they are organic and are released slowly to growing plants. These organic forms of nutrients are less water soluble and, therefore, less likely to leach into groundwater or run off into surface waters. There are several methods to apply biosolids. The selection of the method depends on the type of land and the consistency of the biosolids. Liquid biosolids are essentially 94 to 97 percent water with relatively low amounts of solids (3 to 6 percent). These can be injected into the soil or applied to the land surface. Specialized vehicles are used to inject biosolids into the soil, as shown in Figure 1. These tankers have hoses leading from the storage tank to injection nozzles which release the biosolids. Source: U.S. EPA, 1984. FIGURE 1 BIOSOLIDS INJECTION EQUIPMENT Modified tanker trucks are used for surface application (Figure 2). Biosolids applied to the land surface are usually incorporated into the soil with conventional farm equipment. It is often economical to reduce the volume of biosolids prior to transportation or storage. The amount of water in biosolids can be reduced through mechanical processes such as draining, pressing, or centrifuging, resulting in a material composed of up to 30 percent dry solids. This material will be the consistency of damp soil. Dewatered biosolids do not require any specialized equipment and can be applied with conventional agricultural equipment, such as manure spreaders pulled by tractors. ------- Source: U.S. EPA, 1986. FIGURE 2 LIQUID APPLICATION OF BIOSOLIDS Figure 3 shows the spraying of biosolids, an application method primarily used in forested or reclamation sites. Liquid biosolids are sprayed from a tank towed by a truck or other vehicle. The Environmental Protection Agency's 40 CFR Part 503, Standards for the Use and Disposal of Sewage Sludge (the Part 503 Rule), requires that wastewater solids be processed before they are land applied. This processing is referred to as "stabilization" and helps minimize odor generation, destroys pathogens (disease causing organisms), and reduces vector attraction potential. There are several methods to stabilize wastewater solids, including: • Adjustment of pH, or alkaline stabilization. • Digestion. Composting. Heat drying. The Part 503 Rule defines two types of biosolids with respect to pathogen reduction, Class A and Class B, depending on the degree of treatment the solids have received. Both types are safe for land application, but additional requirements are imposed on Class B materials. These are detailed in the Part 503 Rule and include such things as restricting public access to the application site, limiting livestock grazing, and controlling crop harvesting schedules. Class A biosolids (biosolids treated so that there are no detectable pathogens) are not subject to these restrictions. In addition to stabilization, the Part 503 Rule sets maximum concentrations of metals which cannot be exceeded in biosolids that will be land applied. These are termed Ceiling Concentrations. Part 503 also establishes Cumulative Pollutant Loading Rates for eight metals which may not be exceeded at land application sites. A third set of metals criteria is also included in Part 503, known as Pollutant Concentrations. If these concentrations are not exceeded in the biosolids to be land applied, the Cumulative Pollutant Loading Rates do not need to be tracked. Table 1 shows the three sets of federal limits applicable to biosolids to be land applied. Source: U.S. EPA, 1986. FIGURE 3 APPLICATION OF LIQUID BIOSOLIDS TO FOREST LAND ------- TABLE 1 MAXIMUM METAL CONCENTRATIONS Metal Arsenic Cadmium Copper Lead Mercury Molybdenum Nickel Selenium Zinc NL = No limit Source: U.S. Ceiling Concentration (mg/kg) 75 85 4,300 840 57 75 420 100 7,500 EPA, 1993 and 1994. Cumulative Pollutant Loading Rates (kg/hectare) 41 39 1,500 300 17 NL 420 100 2,800 Pollutant Concentrations (mg/kg) 41 39 1,500 300 17 NL 420 100 2,800 The term Exceptional Quality is often used to describe a biosolids product which meets Class A pathogen reduction requirements, the most stringent metals limits (Pollutant Concentrations), and vector attraction reduction standards specified in the Part 503 Rule. Vectors (flies, mosquitoes, rodents, birds, etc.) Can transmit diseases directly to humans or play a specific role in the life cycle of a pathogen as a host. Vector attraction reduction refers to processing which makes the biosolids less attractive to vectors thereby reducing the potential for transmitting diseases. Exceptional Quality biosolids products are as safe as other agricultural and horticultural products and may be used without site restrictions. APPLICABILITY Land application is well-suited for managing solids from any size wastewater treatment facility. As the method of choice for small facilities, it offers cost advantages, benefits to the environment, and value to the agricultural community. However, biosolids produced by many major metropolitan areas across the country are also land applied. For example, biosolids from the Blue Plains Wastewater Treatment Facility serving the District of Columbia and surrounding communities in Virginia and Maryland have been land applied since the plant began operation in 1930. The cities of Philadelphia, Chicago, Denver, New York, Seattle, and Los Angeles all land apply at least part of their biosolids production. Land application is most easily implemented where agricultural land is available near the site of biosolids production, but advances in transportation have made land application viable even where hauling distances are greater than 1,000 miles. For example, Philadelphia hauls dewatered biosolids 250 miles to reclaim strip-mines in western Pennsylvania and New York City ships some of its biosolids over 2,000 miles to Texas and Colorado. ADVANTAGES AND DISADVANTAGES Land application offers several advantages as well as some disadvantages that must be considered before selecting this option for managing biosolids. Advantages Land application is an excellent way to recycle wastewater solids as long as the material is quality- controlled. It returns valuable nutrients to the soil and enhances conditions for vegetative growth. Land application is a relatively inexpensive option and capital investments are generally lower than other biosolids management technologies. Contractors can provide the necessary hauling and land application equipment. In addition, on-site ------- spatial needs can be relatively minor depending on the method of stabilization selected. Disadvantages Although land application requires relatively less capital, the process can be labor intensive. Even if contractors are used for application, management oversight is essential for program success. Land application is also limited to certain times of the year, especially in colder climates. Biosolids should not be applied to frozen or snow covered grounds, while farm fields are sometimes not accessible during the growing season. Therefore, it is often necessary to provide a storage capacity in conjunction with land application programs. Even when the timing is right (for example, prior to crop planting in agricultural applications), weather can interfere with the application. Spring rains can make it impossible to get application equipment into farm fields, making it necessary to store biosolids until weather conditions improve. Another disadvantage of land application is potential public opposition, which is encountered most often when the beneficial use site is close to residential areas. One of the primary reasons for public concern is odor. In worst case situations, municipalities or counties may pass ordinances which ban or restrict the use of biosolids. However, many successful programs have gained public support through effective communications, an absolutely essential component in the beneficial use of biosolids. Environmental Impacts Despite many positive impacts to the environment, land application can have negative impacts on water, soil, and air if not practiced correctly. Negative impacts to water result from the application of biosolids at rates that exceed the nutrient requirements of the vegetation. Excess nutrients in the biosolids (primarily nitrogen compounds) can leach from the soil and reach ground water. Runoff from rainfall may also carry excess nutrients to surface water. However, because biosolids are a slow release fertilizer, the potential for nitrogen compounds to leach from biosolids amended soil is less than that posed by the use of chemical fertilizers. In areas fertilized by either biosolids or chemicals, these potential impacts are mitigated by proper management practices, including the application of biosolids at agronomic rates (the rate nutrients are used by the vegetation.) Maintenance of buffer zones between application areas and surface water bodies and soil conservation practices will minimize impacts to surface water. Negative impacts to soil can result from mismanagement of a biosolids land application. Federal regulations contain standards related to all metals of concern and application of biosolids which meets these standards should not result in the accumulation of metals to harmful levels. Stringent record keeping and reporting requirements on both the federal and state level are imposed to prevent mismanagement. Odors from biosolids applications are the primary negative impact to the air. Most odors associated with land application are a greater nuisance than threat to human health or the environment. Odor controls focus on reducing the odor potential of the biosolids or incorporating them into the soil. Stabilization processes such as digestion can decrease the potential for odor generation. Biosolids that have been disinfected through the addition of lime may emit ammonia odors but they are generally localized and dissipate rapidly. Biosolids stabilization reduces odors and usually results in an operation that is less offensive than manure application. Overall, a properly managed biosolids land application program is preferable to the use of conventional fertilizers for the following reasons: Biosolids are a recycled product, use of which does not deplete non-renewable resources such as phosphorous. • The nutrients in biosolids are not as soluble as those in chemical fertilizers and are therefore released more slowly. • Biosolids appliers are required to maintain setbacks from water resources and are often subject to more stringent soil conservation and erosion control practices, nutrient ------- management, and record keeping and reporting requirements than farmers who use only chemical fertilizers or manures. • Biosolids are closely monitored. • The organic matter in biosolids improves soil properties for optimum plant growth, including tilth, friability, fertility and water holding capacity. They also decrease the need for pesticide use. A joint policy statement of the U.S. Department of Agriculture, the U.S. Food & Drug Administration, and the U.S. Environmental Protection Agency states, "...the use of high quality biosolids coupled with proper management procedures, should safeguard the consumer from contaminated crops and minimize any potential adverse effect on the environment" (U.S. EPA, 1981). DESIGN CRITERIA Design criteria for land application programs address issues related to application rates and suitable sites. Design criteria for physical facilities (such as stabilization) that are part of land application programs are discussed in separate fact sheets. Biosolids, site, and vegetative characteristics are the most important design factors to consider. Biosolids must meet regulatory requirements for stabilization and metals content. In addition, nutrient content and physical characteristics, such as percent solids, are used to determine the appropriate application rate for the crop that will be grown and the soil in which the crops will be grown. Site suitability is determined based on such factors as soil characteristics, slope, depth to groundwater, and proximity to surface water. In addition, many states have established site requirements to further protect water quality. Some examples include: Sufficient land to provide areas of non- application (buffers) around surface water bodies, wells, and wetlands. • Depth from the soil surface to groundwater equal to at least one meter. • Soil pH in the range of 5.5 to 7.5 to minimize metal leaching and maximize crop growing conditions. Site suitability is also influenced by the character of the surrounding area. While odors and truck traffic many not be objectionable in an agricultural area, both will adversely impact residential developments and community centers close to fields where biosolids are applied. The type of vegetation to be grown is also a design consideration. Vegetation, like soil characteristics, will generally not exclude biosolids application since most vegetation will benefit from the practice. However, the type of vegetation will impact the choice of application equipment, the amount of biosolids to be applied, and the timing of applications. The effect of vegetation on the choice of application equipment is discussed above in the description of this technology. The amount of biosolids that may be applied to a site is a function of the amount of nutrients required by the vegetation and the amount of metals found in the biosolids. Table 2 summarizes the application frequency, timing, and rates for various types of sites. Another factor to be considered in designing a land application program is the timing of applications. Long periods of saturated or frozen ground limit opportunities for application. This is an important consideration in programs using agricultural lands; applications must be performed at times convenient Typical Biosolids Application Rate Scenario The recommended minimum amount of nitrogen needed by a typical corn crop to be grown in New Jersey is 120 pounds per acre per year. Biosolids containing 3 percent nitrogen could be applied at up to 5.4 dry tons per acre if used to supply all the nitrogen needed by the crop (i.e., no other nitrogen fertilizers used.) A city producing 10 dry tons of biosolids per day would require access to almost 700 acres of corn. If the biosolids contained only 1.5 percent nitrogen, twice as many tons could be applied per acre, requiring only half as many acres to land apply the same amount of biosolids generated. ------- TABLE 2 TYPICAL BIOSOLIDS APPLICATION SCENARIOS Type of Site/Vegetation Agricultural land Corn Small grains Soybeans Hay Forest land Range land Reclamation sites Schedule April, May, after harvest March-June, August, fall April-June, fall After each cutting Year round Year round Year round Application Frequency Annually Up to 3 times per year Annually Up to 3 times per year Once every 2 - 5 years Once every 1 - 2 years Once Application Rate 5 to 1 0 dry tons per acre 2 to 5 dry tons per acre 5 to 20 dry tons per acre 2 to 5 dry tons per acre 5 to 1 00 dry tons per acre 2 to 60 dry tons per acre 60 to 100 dry tons per acre Source: U.S. EPA, 1994. to the fanner and must not interfere with the planting of crops. Most application of biosolids to agricultural land occurs in the early spring or late fall. As a result, storage or an alternate biosolids management option must be available to handle biosolids when application is not possible. Forest lands and reclamation sites allow more leeway in the timing of applications. In some areas of the United States, application can proceed year round. Application is most beneficial on agricultural land in late fall or early spring before the crop is planted. Timing is less critical in forest applications when nutrients can be incorporated into the soil throughout the growing period. Winter application is less desirable in many locales. Rangelands and pasturelands also are more adaptable to applications during various seasons. Applications can be made as long as ground is not saturated or snow covered and whenever livestock can be grazed on alternate lands for at least 30 days after the application. The timing of single applications in land reclamation programs is less critical and may be dictated by factors such as regulatory compliance schedules. PERFORMANCE In 1995, approximately 54 percent of wastewater treatment plants managed biosolids through land application, an increase of almost 20 percent from information reported in 1993 (WEF, 1997 and U.S. EPA, 1993.) The vast majority of these land application programs use agricultural land, with minor amounts applied to forest lands, rangelands, or land in need of reclamation. The use of land application increased steadily in the 1980s for several reasons, including decreasing availability and increasing costs associated with landfill disposal. Research also helped refine procedures for proper land application. Meanwhile, implementation of the Nationwide Pretreatment Program resulted in significant improvements in biosolids quality. The 1993 adoption of the Part 503 Rule created a structure for consistent application procedures across the nation. The regulations were developed with input from the U.S. Department of Agriculture, the U.S. Food and Drug Administration, biosolids generators, environmental groups, the public, state regulators, and academic researchers. Conservative assumptions were used to create regulations to "protect public health and the environment from all reasonably anticipated adverse effects" (U.S. EPA, 1993). Land application is a reliable biosolids management option as long as the system is designed to address such issues as storage or alternate management for biosolids during periods when application cannot take place due to unfavorable weather or field conditions. Public opposition rather than technical constraints is the most common reason for discontinuing land application programs. ------- "/n fact, in all the years that properly treated biosolids have been applied to the land, we have been unable to find one documented case of illness or disease that resulted." Martha Prothro, Former Deputy Assistant Administrator for Water, U.S. Environmental Protection Agency. Source: Water Environment Web, 1998. OPERATION AND MAINTENANCE Land application systems generally use uncomplicated, reliable equipment. Operations include pathogen reduction processing, dewatering, loading of transport vehicles, transfer to application equipment, and the actual application. Operations and maintenance considerations associated with pathogen reduction processing are discussed in other fact sheets. The other operations require labor skills of heavy equipment operators, equipment maintenance personnel, and field technicians for sampling, all normally associated with wastewater treatment facilities. In addition, the biosolids generator is responsible for complying with state and local requirements as well as federal regulations. The biosolids manager must be able to calculate agronomic rates and comply with record keeping and recording requirements. In fact, the generator and land applier must sign certification statements verifying accuracy and compliance. The generator should also allocate time to communicate with farmers, landowners, and neighbors about the benefits of biosolids recycling. Control of odors, along with a viable monitoring program, is most important for public acceptance. COSTS It is difficult to estimate the cost of land application of biosolids without specific program details. For example, there is some economy of scale due to large equipment purchases. The same size machine might be needed for a program that manages 10 dry tons of biosolids per day as one managing 50 dry tons per day; the cost of that machine can be spread over the 10 or 50 dry tons, greatly affecting average costs per dry ton. One source identified costs for land application varying from $60 to $290 per dry ton (O'Dette, 1996.) This range reflects the wide variety in land application methods as well as varying methods to prepare biosolids for land application. For example, costs for programs using dewatered biosolids include an additional step whereas costs for programs using liquid biosolids do not reflect the cost of dewatering. They do, however, include generally higher transportation costs. Despite the wide range of costs for land application programs, several elements must be considered in estimating the cost of any biosolids land application program: Purchase of application equipment or contracting for application services. Transportation. Equipment maintenance and fuel. • Loading facilities. • Labor. Capital, operation and maintenance of stabilization facilities. • Ability to manage and control odors. Dewatering (optional). Storage or alternate management option for periods when application is not possible due to weather or climate. • Regulatory compliance, such as permit applications, site monitoring, and biosolids analyses. • Public education and outreach efforts. Land must also be secured. Some municipalities have purchased farms for land application; others apply biosolids to privately held land. Some operating costs can be offset through the sale of the biosolids material. Since the biosolids ------- reduce the need for fertilizers and pH adjustment, farmers sometimes pay to have biosolids applied to their lands. REFERENCES Other Related Fact Sheets Odor Management in Biosolids Management EPA 832-F-00-067 September 2000 Centrifugal Dewatering/Thickening EPA 832-F-053 September 2000 Belt Filter Press EPA 832-F-00-057 September 2000 Filter Press, Recessed Plate EPA 832-F-00-058 September 2000 Alkaline Stabilization of Biosolids EPA 832-F-00-052 September 2000 Other EPA Fact Sheets can be found at the following web address: http://www.epa.gov/owmitnet/mtbfact.htm. 1. O'Dette, R.G., 1996. Determining the Most Cost Effective Option for Biosolids and Residuals Management. In Proceedings of the 10th Annual Residuals and Biosolids Management Conference: 10 Years of Progress and a Look Toward the Future. Alexandria. Water Environment Federation. 2. Sopper, W.E., Seaker, E.M., and Bastian, R.K., Editors, 1982. Land Reclamation and Biomass Production and Municipal Wastewater and Sludge. University Park. The Pennsylvania State University Press. 7. 9. 10. U.S. Environmental Protection Agency, 1995. Amendments to the Standards for the Use or Disposal of Sewage Sludge (40 Code of Federal Regulations Part 503). Washington, D.C. U.S. Environmental Protection Agency. U.S. Environmental Protection Agency, 1994. Biosolids Recycling: Beneficial Technologies for a Better Environment. EPA 832-R-94-009. Washington, D.C. U.S. Environmental Protection Agency, Office of Water. U.S. Environmental Protection Agency, 1993. Standards for the Use or Disposal of Sewage Sludge (40 Code of Federal Regulations Part 503). Washington, D.C. U.S. Environmental Protection Agency. U.S. Environmental Protection Agency, 1991. National Pretreatment Program: Report to Congress (EPA 21 W-4004.). Washington, D.C. U.S. Environmental Protection Agency. U.S. Environmental Protection Agency, 1986, Sewage Sludge Management Primer, Technology Transfer Series. Cincinnati. U.S. Environmental Protection Agency. U.S. Environmental Protection Agency, 1984. Environmental Regulations and Technology, Use and Disposal of Municipal Wastewater Sludge (EPA 625/10-84-003.) Cincinnati. U.S. Environmental Protection Agency. U.S. Environmental Protection Agency, 1983. Process Design Manual Land Application of Municipal Sludge (EPA 625/1-83-016.) Cincinnati. U.S. Environmental Protection Agency. U.S. Environmental Protection Agency, 1981. Inter agency Policy on Beneficial Use of Municipal Sewage Sludge. Washington, D.C. U.S. Environmental Protection Agency. ------- 11. Water Environment Federation, 1997. National Outlook - State Beneficial Use of Biosolids Activities. Washington, D.C. Water Environment Federation. 12. Water Environment Web, http://www.wef.org/doc/bioquotes.html, Septembers, 1998. 13. Water Quality Management Library, 1992. Municipal Sewage Sludge Management- Processing, Utilization and Disposal, ed. Cecil Lue-Hing, David R. Zenz, Richard Kuchenrither. Lancaster. Technomic Publishing Company, Inc. ADDITIONAL INFORMATION Cecil Lue-Hing & Associates, Inc. Cecil Lue-Hing 6101 N. Sheridan Street, 40B East Chicago, IL 60660 Denver Metro Wastewater Reclamation District Steve Frank 6450 York Street Denver, CO 80229 District of Columbia Water and Sewer Authority Chris Peot 5000 Overlook Avenue, S.W. Washington, D.C. 20032 Forste Associates Jane Forste 897 Laurel Way Arnold, MD 21012 The mention of trade names or commercial products does not constitute endorsement or recommendations for use by the United States Environmental Protection Agency (EPA). For more information contact: Municipal Technology Branch U.S. EPA Mail Code 4204 1200 Pennsylvania Avenue, NW Washington, D.C. 20460 IMTB Excellence h compliance through optfrnal technical solutfons MUNICIPAL TECHNOLOGY BRANCH ------- |