Research & Development

Investment in research & development for new animal waste management technologies has significant potential to improve animal production efficiency and reduce the negative environmental impacts of meat production. However, technological improvements must first and foremost be financially feasible for individual farmers before they can be implemented on a broader scale.  

In recent decades, major pork processors have committed to improving their waste management practices through technological initiatives on company-owned farms.  This section reviews two of these agreements, then outlines a series of technologies that were developed through these unique research and development initiatives.

 

Premium Standard Farms

The State of Missouri and Premium Standard Farms entered into a consent agreement in 2004 which provided that Premium Standard Farms would establish and install “Next Generation Technologies” on company-owned swine operations in Missouri that would reduce waste nutrient content, pathogens, odor, and air pollutants stemming from the farms' lagoons. One Next Generation Technology utilizes digesters and scrapers to mechanically remove the waste from underneath the confinement barns and into the lagoon. Scrapers were found to be an odor-reducing technology, and have since been installed on Premium Standard Farms-owned operations.

 

the Smithfield Agreement

A second agreement promoting the development of novel waste management technologies is the Smithfield Agreement, ratified in 2000 between the State of North Carolina and Smithfield Foods in the wake of Hurricane Floyd. The Smithfield Agreement required Smithfield Foods and its subsidiaries to fund the development of Environmentally Superior Technologies for waste management on new and existing swine CAFOs. Based on North Carolina's Swine Waste Management Performance Standards, each technology system was measured for its ability to substantially reduce or eliminate nitrogen and phosphorous, copper and zinc, atmospheric emissions of ammonia, odor, and disease transmitting vectors and airborne pathogens from the farms' waste management system. A resulting Smithfield Agreement study concluded that an Environmentally Superior Technology for managing swine waste on Smithfield-owned hog operations consisted of the “Super Soils” Generation 1 in combination with “Orbit” High Solids Anaerobic Digestion, “BEST” fluidized bed combustion of solids, “RE-CYCLE” gasification of solids, or “Super Soils” solids compost. However, the Super Soils technology was not implemented on Smithfield-owned swine farms, because it failed the “economically feasible” component of the Smithfield Agreement criteria.

 

Current technological breakthroughs

 

1 - This chart offers a general summary and overview to help clarify the major differences between some WTE technologies - this list is neither comprehensive nor all-inclusive. Information is drawn from a 2006 NCSU Phase III Technology Determinations Report but does not constitute as a substitute for that information.  Please consult the report for more information.
2 - Odor reduction is generalized for comparison purposes; all technologies demonstrated some degree of odor reduction compared to lagoons/sprayfields.
3 - Key: M = Mechanical, primarily in troubleshooting equipment; E = Electrical; HS = High school education; Sp = Specialized skills, either referring to specialized equipment, advanced computer skills, or more advanced scientific or other technical training required.
4 - Costs refer to annual estimated costs; dollar signs offer extremely rough estimates for comparison purposes only, with $ equivalent to the cost of maintaining the status quo of lagoon/sprayfield.  Costs may change as technologies become more cost-effective.  See NCSU report (above) for precise estimates of annual cost.

 

Anaerobic Digester with Aeration Basin

DCOI LRF.jpg

Anaerobic digestion is a natural biological process in which microbes break down organic matter, such as swine waste, in the absence of oxygen. Anaerobic digesters store the organic material and capture and sequester the gasses (known as "biogas") produced by the bacteria. A typical anaerobic digester serving a swine farm consists of a a clay basin into which the swine waste is flushed. The lined lagoon is then covered with a plastic cover to prevent oxygen from entering and to prevent biogas from escaping. If the digester is part of a waste-to-energy system, the captured biogas is conditioned, refined, compressed, and sent to a micro-turbine, which generates electricity for on-farm operations. Excess methane is flared off, converting it to carbon dioxide, a much less potent greenhouse gas than methane. The waste in the anaerobic digester is then transferred into a separate un-covered lagoon, known as an "aeration basin", where it undergoes further biological processes to convert the ammonia into nitrogen gas for release into the atmosphere. This step reduces the overall nitrogen content of the waste.

An anaerobic digester and nitrification waste-to-energy system has been implemented successfully at Loyd Ray Farms in Yadkinville, NC, to reduce environmental impacts, generate renewable energy, and produce carbon credits.

 

“Orbit” High Solids Anaerobic Digestion (HSAD)

The Orbit HSAD technology functions similar to a moderate temperature (20-45°C) anaerobic digester like the one described above, except it uses high temperature (41-122°C) anaerobic digestion and bacteria that can adapt to 54.4°C. The higher temperature enables digestion of waste with higher solid concentrations of 35-40%, as well as improving efficiency of anaerobic microbes.

 

Scrapers

 Manure scraper.  Source : University of Missouri.

Manure scraper. Source: University of Missouri.

Scrapers are a machine that automatically removes waste from underneath CAFO confinement barns into a drainage pipe, which leads to the waste lagoon. A Premium Standard Farms study, done in partnership with Iowa State University, compared automated scraping systems with tip-tank flush systems for use at swine barns with shallow pits. Flush systems use water (or lagoon effluent) to flush the waste from underneath the barns when waste in the collection tank reaches a certain level. Compared to deep pit systems, scraper systems significantly reduce ammonia, odor, hydrogen sulfide, and greenhouse gas emissions. However, retrofitting deep pit farms for scrapers requires modification of the pits, which can be expensive.

 

“BEST” Fluidized Bed Combustion of Solids

Both versions of the “BEST” waste management system studied separate solid waste with dry matter content of 30% or higher from the liquid waste flushed from barns. This separation reduces the organic content of the liquid waste that must undergo further treatment, and provides manure solids that can be used in other ways. Fluidized bed combustion tests can be used to determine the energy value and emissions of the solids, and test the resulting ash for value as a fertilizer.

 

“RE-CYCLE” Gasification of Solids

This system uses belt manure removal to separate the solid and liquid waste. The solids are burnt in a low-oxygen environment to release gases like methane, carbon monoxide, and hydrogen. The gases are collected and used to make fuel-grade ethanol. The ash produced may be used as a fertilizer or feed supplement. Pathogens are destroyed by the high temperature of gasification. The liquid waste receives treatment in a sequencing batch reactor.

 

“Super Soils” Processing System

 Super soils system on a farm in North Carolina. Source: Vanotti, USDA.

Super soils system on a farm in North Carolina. Source: Vanotti, USDA.

The “Super Soils” system was one of the waste management technologies evaluated under North Carolina's Smithfield Agreement. It was tested at a North Carolina hog farm raising 4,000 hogs. The Super Soils system separates the solid waste from the liquid waste using a flocculating agent. The solids are taken offsite, composted, used in a fertilizer blend, bagged, and sold for off farm use. The liquid waste receives further treatment. Nitrogen is removed from the waste by converting it to gas. This is accomplished by cycling the waste between tanks that convert nitrogen through a several-step-process from ammonia to nitrogen gas. Most of the treated liquid waste is then stored until it is used to recharge the pits underneath the barns, although some of the liquid waste is treated for soluble phosphorous removal.

Since the start of the Smithfield Agreement study, the Super Soils technology has been updated twice. The latest version of this initiative is the “Terra Blue” System. It uses solid-liquid separation, biological nitrogen removal, and disinfection and phosphorus removal unit processes to treat swine waste. “Terra Blue” was implemented on a farrow-to-finish operation with 1,200 sows and 12,960 hogs. With this system, some of the wastewater goes on to be treated with lime, which separated the phosphorous from the waste and disinfects the effluent. The phosphorus treated water is stored in a former lagoon and used for crop irrigation. The phosphorous precipitate is looped back to the solid separation unit and leaves the farm with the manure solids.

 

“AgriClean” Mesophilic Digester and “AgriJet” Flush System

This system was implemented at a farm with 12 barns and 11,520 hogs, where five barns were flushed using water pressure from the AgriJet system. After daily flushing, the waste enters an underground tank where it is pumped to a fixed-film mesophilic digester. Methane is then flared, while solids and liquids are separated. Solids are land applied, and the liquid waste stored in a lagoon.

 

Innovative Sustainable Systems Utilizing Economical Solutions (“ISSUES”)

The first ISSUES technology is the RENEW System, which uses a mesophilic digester, a microturbine generator, aeration and a wastewater filtering, and disinfection systems. The waste flows from an underground tank to the digester. The digester produces biogas to fuel the microturbine, generating electricity. From there, the waste flows to a polishing storage basin, then to an aerobic digester where it undergoes nitrification. Some of the waste returns to the polishing basin and is either recycled to flush the barns or land applied. Other waste flows to a sand carbon filters and reverse osmosis filtration system. Then it is disinfected using ozonation and ultraviolet light, and used as drinking water for the pigs.

The second technology is a patented permeable lagoon (“Bio-Cap ML”). The waste flows from the barns to the covered anaerobic lagoon, which reduces ammonia emissions and odor. Next the waste flows to an aerated nitrification pond, and then to a denitrification/irrigation storage pond until it is used to flush the barns or applied to land.

The third technology is an aerobic blanket. Instead of covering the lagoon with a permeable cover, it covers it with a layer of aerated water. Like the permeable cover, the aerated layer reduces ammonia emissions and odor.

 

Solids Separation/Constructed Wetlands System

Solids are extracted from waste and used off-farm. The waste flows through eight acres of constructed wetlands before entering an irrigation pond. Microbes in the root-zone of plants convert ammonia into nitrogen gas. From there, the waste flows to an irrigation pond.

A similar system uses earthen, synthetically lined wetland basins to remove nitrogen from the waste. The basins are filled with gravel, which serve as substrates for microbes. The waste flows from the barns to a settling tank that removes solids. The liquid waste continues on, to be pumped back and forth between the wetland basins. As the waste fills one basin, anaerobic conditions take hold and denitrification occurs. As the waste is pumped out of the basin, aerobic conditions take hold and nitrification occurs. After six days, the liquid waste is recycled to flush the barns and excess liquid is applied to land as fertilizer.

 

End-of-pipe Scrubber Systems

 Farm in the Netherlands.

Farm in the Netherlands.

Scrubber systems work by directing the gases emitted from animal waste through a cylinder of packing material (and often scrubbing liquid) that traps particulate matter, and resulting in a cleaner gas to enter the ambient air.

Scrubbers reduce emissions from CAFOs by close to 100%, and bioscrubbers by around 70%. In 2011, 10% of exhaust air from swine CAFOs in the Netherlands was treated using scrubber systems. Emerging "multi-pollutant scrubbers” have the potential to remove odor and particulate matter (PM10 and PM2.5) as well as ammonia.

 

“Environmental Technologies” Closed Loop Technology

The closed loop technology system, employed at a farm with 3,700 hogs, flushes waste into an equalization tank, before it is pumped onto an inclined-screen separator. The separated solids are land-applied or used in compost. The liquid waste is injected with a polymer flocculant and sanitizer/disinfectant, and then pumped into a settling tank. The flocculated solids settle to the bottom. The liquid waste is reused as flush water. Any excess liquid undergoes filtration and aeration before it is blended with well water to meet the solids content concentration level that satisfied human drinking water standards. The resulting water is used as drinking water for the hogs.

 

Integrated Bioresource Recovery System

This system integrates anaerobic digestion, biofilter nitrification, and greenhouse tomato production to manage hog waste. The study was done at Barham Farm, in Zebulon, NC, which raises 4,000 hogs.

The waste first flows from pits underneath the barns to an ambient-temperature in-ground anaerobic digester with an impermeable cover. The digester produces methane which fuels a generator producing electricity for the farm. Heat from the generator is also captured and used for on-farm use. The digester and methane recovery and utilization system were constructed under the U.S. Environmental Protection Agency AgSTAR Program prior to the Smithfield Agreement study.

Following the digester, the waste flows to a lagoon. Some of the effluent then goes through nitrification biofilters, which convert the ammonia into nitrate and produce nitrified water. The nitrified water is used to recharge the pits underneath the barn every eight days, which otherwise would have wastewater denitrifying into odorless nitrogen gas. The remaining lagoon effluent is used to fertilize plants and vegetables grown in on-site greenhouses via an automated irrigation system. Excess lagoon effluent is land-applied.

 

Manure Solids Conversion to Insect Biomass

The Manure Solids Conversion system uses black soldier fly larvae to digest swine manure. The waste is placed concrete pits that have edges sloped at 45-degree angles. At the top of the pit, there is a gutter with an attached bucket. The larvae are put in with the waste, and will digest the manure until they become prepupae. At that life stage, they will crawl up the slopes, fall into the gutter, and then fall into the bucket.

The digestion process cuts the amount of manure in half. The residue is dry, has a lower nutrient content and produces fewer odors. The residue could be used to feed swine, poultry and fish.

 

Ekokan Up-flow Biofilter

First the waste goes through a screening process that removes large solids, and then the liquid waste flows to an equalization tank. Next the liquid waste flows up through four biofilters, which are supplied with air via blowers at the bottom. The biofilters contain a substrate for a biofilm of bacteria that biologically degrade organics, odor, and convert ammonia into nitrate. The effluent then gravity flows to a storage tank where it is rerouted back to the solid separation basin or used to recharge the barn pits.

 

What constitutes an
"Environmentally Superior Technology"?

Many of these technologies are extremely promising, and experimentation is ongoing to improve them for future use by more farmers.  Nevertheless, these technologies can be expensive to implement on farms that already exist, and may impose significant costs relative to maintaining the status quo of a lagoon and sprayfield.  Because "economic feasibility" is part of the definition of an Environmentally Superior Technology (EST), none of the technologies reviewed qualify as an EST for existing farms as of this writing. 

However - for new farms, as of the Phase III technology determination report by North Carolina State University, the Super Soils technology combined with one of the following - the ORBIT high-temperature digester, a Super Soils composting facility, Re-Cycle gasification, or the BEST fluidized bed combustion of solids - constitutes an Environmentally Superior Technology.