In general, the answer to this question is no. Biosolids are delivered in 6-1000 gallon loads when liquid, and 20-30 cubic yards at a time when brought in as dewatered biosolids, compost or advanced alkaline stabilized sludge (AASS). It would be difficult and very expensive to test each load, and the testing takes several days to weeks to complete, so the biosolids would need to be held separately prior to application.

Biosolids are tested every four months following the first application by the permitted operator, and these analyses are submitted to the appropriate regulatory agency. The agency issues an approval which states that the biosolids meet heavy metal and organics quality standards, and whether the material meets the minimum requirements for stabilization. The applier or processor of the biosolids makes additional tests of the material during permitting before utilization. As part of the permitting process, the permittee must include 3 chemical analyses of the material from each sewage treatment facility or other source. A good biosolids recycler looks for material which is consistent in quality. By looking at 6-12 months of biosolids data, one can determine if the material routinely meets applicable standards, or if the quality is more variable. If the product is of variable quality and sometimes exceeds the allowable concentrations of some chemicals, more care must be taken in using these biosolids in direct land application.

There are some safeguards against this occurring, but most rely upon the honesty of the generator, hauler or land applier. The regulatory agency makes routine, unannounced inspections of land application or biosolids processing facilities. They can, and do, take samples during these visits. There is no particular advantage to an unscrupulous waste hauler to try to dispose of illegal wastes at a biosolids management site. Such sites are regulated and regularly inspected, most of the operators of the sites haul as well as apply the biosolids. If they contaminate the site, they will be losing an outlet for the biosolids they are contracted to manage. It is unlikely that the profit they would make from illegally disposing of a chemical would make up for the loss of the site for biosolids management.

When biosolids are land applied, often the land owner is different from the biosolids applier. Frequently, these land owners are farmers, who derive the majority of their income from producing crops. There would be no incentive for them to contaminate their land, and often the agreements with the biosolids appliers require the applier to clean up the soil should some contamination occur. In addition, the land owners often do independent testing to insure the results being submitted by the biosolids generators or land appliers are accurate. Lastly, under current regulations, soil and groundwater testing are done routinely by certified laboratories. Such testing can act as the final check that no illegal disposal has taken place and contaminated either the soil or the groundwater.

The short answer is yes, there are odors associated with even well run biosolids facilities. These odors are generated by the application and processing of biosolids, but when properly operated, such odors should not be long-lived nor at levels which would be a nuisance for adjacent property owners.

The actual odors have been described as ‘musty”, or ‘earthy’, when describing the injection of liquid biosolids or the application of compost. Ammonia odors are associated with AASS or lime stabilized biosolids, often because the chemical reaction of the lime and the biosolids drives off the ammonia. Composting facilities will also have an earthy odor associated with them, and may sometimes smell like a wastewater treatment plant, depending upon the type of process used to compost the biosolids and the degree of air pollution control equipment installed at the facility. The odors associated with normal farm application of animal manure, especially when surface applied, are much worse than those caused by well operated biosolids facilities.

The surface application of liquid or dewatered biosolids or poorly cured AASS can cause off-site odor problems. Even well operated processing facilities will sometimes experience operational upsets which will cause odors to leave the immediate vicinity of the site. Rapid and complete incorporation of the biosolids on the day they are applied, or the use of lime over the applied biosolids, will reduce the odors from surface application.

When a facility is sited or constructed in a town where homes are in close proximity to the site, the operator, residents and township officials must come together to address resident’s concerns over potential odors, and to set up a mechanism for the residents and operator to work together when odor problems occur. This could be as informal as the operator providing the residents with phone numbers and contact persons at the plant to call when problems occur, or as formal as a Citizens Advisory Committee (CAC) which would oversee the operation of the facility and which would react to citizen complaints of odors.

When the biosolids used to fertilize a food crop meet the EPA standards for heavy metals and destruction of pathogens, that crop is safe for human consumption. Current Federal standards have no restrictions as to what crops may be grown when a biosolid meets the Exceptional Quality and Class A Pathogen Reduction standards found in 40 CFR Part 503. Materials such as compost, or the AASS material which meet this standard, could be used to grow any crop consumed by humans.

Much research has gone into examining how food crops are affected by biosolids application. Where pathogens have been destroyed, such as through composting, and heavy metal levels are at or below the Exceptional Quality standards, there is no contamination of the edible portion of the crop through the use of biosolids. It may be of interest that many commercial fertilizers used by farmers and home gardeners contain levels of heavy metals similar to or greater than those found in biosolids meeting the Exceptional Quality standard.

Current Federal standards allow the sale of crops grown on biosolids, with restrictions being based on the quality of the biosolids. When biosolids meeting the Class A Pathogen Reduction and Exceptional Quality metal standards are used, there is no restriction within the Federal regulations on the use of the crop.

Some standards restrict crops to non-food chain crops, such as hay or straw, or to crops which are processed before being eaten, such as vegetables going to a processor, or foods which would not be eaten raw by the consumer. Often, biosolids may not be applied to areas where tobacco is grown or will be grown and areas where root vegetables or vegetables which are eaten raw will be grown within 2 to 3 years. This restriction is for biosolids which do not meet the Class A Pathogen Reduction standards, but which do meet the current standards for heavy metal quality.

Below is a table showing current Federal standards, for the heavy metals regulated by the Federal 503 standards.

Metal Federal 503 Exceptional Federal 503 Maximum
Arsenic 41 75
Cadmium 39 85
Copper 1,500 4,300
Mercury 17 57
Molybdenum n/a 75
Nickel 420 420
Lead 300 840
Selenium 100 100
Zinc 2,800 7,500

Regulations vary from state to state, but usually liquid and dewatered biosolids used in place of commercial fertilizers must be applied during the growing season, roughly March 1 to November 15, depending upon where the site is located. These materials cannot be applied to frozen or snow-covered ground, or immediately after a heavy rain when the soil is saturated. Products, such as compost or AASS, may be applied year-round so long as the application does not result in excessive runoff. These products may be applied in the winter, and may be applied to frozen ground. They are treated like any other agricultural products for which they are a substitute.

The testing required by the permits for biosolids management facilities require that the testing be done by State certified laboratories, and the testing is paid for by the permitted site operator. The regulatory agency may collect samples during their routine inspections, and these samples are analyzed by them in-house.

Should a problem occur, such as odors, groundwater contamination, or some other violation of the permit, the permittee is responsible to correct the problem. Depending upon how the problem occurred, the permittee may also be fined or otherwise prosecuted by the regulatory agency. With respect to indemnification, there is currently no program that would indemnify the township where a facility is located, nor which would protect landowners participating in a beneficial reuse program.

It is noteworthy that most beneficial use projects are substituting biosolids for other agricultural chemicals, such as inorganic fertilizers. The use of these products is not regulated, and in many cases these materials contain heavy metals at levels similar to or higher than biosolids. When used as a fertilizer, biosolids actually pose a significantly lower danger to the groundwater, particularly from nitrogen contamination. Much of the nitrogen in biosolids is in the organic, or slow release form. This form of nitrogen is released slowly over the growing season, and is not as subject to leaching as inorganic nitrogen fertilizers. The organic matter in biosolids also reduces nutrient leaching, binds heavy metals present in the soil and biosolids, and improves soil texture and water holding capacity.

The biggest change was be the adoption of the Federal biosolids management regulations, 40 CFR Part 503. These regulations, which were established using environmental and health risk based assessments, provide a scientific basis for the use of biosolids throughout the United States.

When used in land reclamation or in agriculture at rates based on crop nutrient needs, biosolids will not harm the environment or impact human health. There is extensive research establishing that the long-term use of biosolids is safe and will not cause degradation of ground or surface waters, soils, will not adversely affect crops grown on these soils, nor affect animals fed the crops or grazed on land where biosolids were applied.

Like any chemical used in production agriculture, biosolids must be used in accordance with sound agronomic practices and must meet the standards set by the Federal and State government if it is to remain safe and effective. Federal regulations set down minimum requirements for quality and management techniques, and the states can impose more stringent requirements to meet special circumstances or concerns within a particular region.

Biosolids have been used safely for many years, and we have the information necessary to make judgments concerning the proper quality and quantity of biosolids needed by crops while providing a high level of environmental protection. There remains disagreement within the scientific community over some of the heavy metal standards. It is unlikely that everyone will ever agree over the safety of many of the products we use every day. As our knowledge grows, we can modify the standards to make the practice of recycling biosolids safer and more acceptable, but we can begin to more widely utilize this valuable and misplaced resource now without fear we will be ruining our or our children’s environment or health.

Land Application of Biosolids Questions and Answers for Farmers

Sewage sludge or biosolids are the residue of material removed from sewage during the treatment process. Biosolids consist mainly of the bodies of dead bacteria, but there are also insoluble materials such as nutrients, sand and silt. Biosolids are not raw human wastes or the material filtered from untreated sewage!

Biosolids have been used as a substitute for commercial fertilizers in the United States for over 50 years. While you will get many opinions about the use of biosolids, most experts agree that the use of clean biosolids (low in heavy metals) at rates which meet the crop nitrogen need is a sound agricultural practice, and will not result in a risk to the farmer’s health or a danger to his neighbors, nor will it lead to a degradation of the surrounding environment.

All biosolids which are used on agricultural land in New Jersey must be stabilized. This process destroys the harmful bacteria and reduces the potential for odors from the sludge after application. Biosolids which are stabilized by aerobic or anaerobic digestion will have an earthy, musty odor. Biosolids stabilized by the use of lime will have an ammonia odor for several hours after being applied to the field. Most biosolids are applied in the liquid form, and are injected into the soil during application. This eliminates all but a very faint earthy odor, detectable at the edges of the field where material has been applied.

Many biosolids used as a fertilizer now being used on farms are in a liquid form, having a solids content of less than 6%. These biosolids are usually injected into the soil by specialized equipment, and little or no biosolids are visible on the ground surface after application. In most cases, biosolids are applied to fallow ground, but there are farms that inject biosolids into a perennial grass hay sod with excellent results. Liquid biosolids may also be applied to the surface of the ground as long as there is a growing crop, or the soil is disced or plowed within 24 hours of application. Some biosolids are applied in the dewatered form, similar to dairy manure. A manure spreader is used, and in this case the biosolids must be tilled into the soil within 24 hours of application.

The State regulations allow biosolids to be applied as a substitute for the nitrogen a farmer might normally use on his crops. This means that biosolids can be applied at a rate equal to the Extension Service recommendation for nitrogen for the particular crop being produced. A farmer using biosolids, therefore, saves on the cost of nitrogen and phosphorus fertilizers, as well as obtaining a portion of the potassium requirements of the crops.

A second benefit is the improvement in soil tilth, which comes from the addition or organic matter in the biosolids. Biosolids are 60 – 70% organic matter, and this will improve the water holding capacity of the soil.

Thirdly, the nitrogen in the biosolids is partially in the organic form. This means that this nitrogen is released slowly over the entire growing season, thereby reducing the potential of a rainstorm washing out all the seasons nitrogen before the crop has had a chance to use it. The organic portion the biosolids represents 30-60 lbs of the total N available over the growing season.

There are positive aspects to the use of biosolids on farmland, as well as some inconveniences. For many farmers, the positive aspects far outweigh these inconveniences. Because a permit is required from the State, the land application operation is subject to inspection by the regulatory agency. These inspections are very infrequent, and do not involve the farm operation outside those directly associated with the application or storage of biosolids.

There are slight odors sometimes associated with the application of biosolids, these odors being noticeable immediately adjacent to the field being used. Often neighbors or the township will object to the issuance of the permit. The permit application process requires notice to the township, and good practice suggests that the neighbors also be notified. These objections can often be alleviated by a visit to an operating site, where these people can see that there will not be any major odor or other environmental problems associated with the site. There may, however, be some degree of ongoing objection to the operation until the site has been operated for some time without the problems feared by those living near the site.

The actual application of the biosolids is perhaps the biggest inconvenience to the farmer. In most operations, only 8-10 acres per day can be completed due to the volumes of biosolids needed to meet most crop nitrogen needs. Biosolids cannot be applied during rainy days or on wet fields, so biosolids cannot be applied as quickly as commercial fertilizers. By having adequate equipment, however, the biosolids applier can work with the farmer to complete fields quickly as they become available for planting.

Overall, the experience of farmers using biosolids has been that the benefits far outweigh the minor inconveniences associated with using biosolids as your source of nitrogen.

All biosolids and biosolids derived products, no matter what the source, contain some heavy metals. The biosolids used on farmland are tested at least monthly for heavy metal content, and the DEP approves each source of biosolids prior to allowing application to the farm. The state sets limits for the amount of each metal allowed in the biosolids, and these limits are among the most stringent in the nation.

When biosolids are applied to land with the proper soil pH (6.5 or greater), the metals are bound to the soil particles, and do not move into either the crop or the groundwater. The permit issued by the State requires that the soil pH be maintained at 6.5 or higher, thus insuring that the heavy metals do not contaminate the soil, crop or water. In addition, there are maximum amounts of metal which may be applied over the life of the site, with these limits being set by the Federal government. These limits further safeguard the farmer and the general public by insuring that no matter what the future use of the land, there will be no risk of a health or environmental hazard. Because of the high standard New Jersey sets for biosolids going onto farmland, it takes a minimum of 100 years to reach the load for the most restrictive metal, which in most cases is copper.

There is a wealth of evidence which shows that when biosolids meeting limits for metals is used in place of fertilizer, there is no danger to either the farmer, his neighbors or the general public.

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