The long-awaited, five-year, $17.3 million study to identify effective swine manure management alternatives is nearing completion.

North Carolina's pork industry experienced an unprecedented growth spurt beginning in the mid-'70s, with 2.7 million hogs, then culminating at about 10 million head when a building moratorium was enacted in 1997.

The production stalemate caused by the mandatory moratorium barred the building of new swine production facilities utilizing the anaerobic lagoon and spray-field technology, the low-cost manure storage and treatment system considered the standard in the state.

With the rapid growth came environmental, social and political scrutiny centered on water and air quality issues associated with hog density, and the traditional manure-handling methods on the state's approximately 2,000 production sites.

In the summer of 2000, the state's attorney general entered into agreements with the state's largest pork producer, Smithfield Foods, its subsidiaries, and Premium Standard Farms. Those companies funded a monumental effort to identify and develop environmentally superior technologies (EST) that could replace the popular lagoon-spray-field systems.

Smithfield Foods contributed $15 million, while Premium Standard Farms added $2.3 million to the research till. In March 2002, the state's attorney general accepted a third agreement with Frontline Farmers, a group of independent contract hog finishers who offered their facilities to develop and implement the ESTs selected.

C.M. (Mike) Williams, director of the Animal and Poultry Waste Management Center at North Carolina State University (NCSU), led the charge to select and evaluate 16 EST candidates.

The agreement also mandated “comprehensive determinations of economic feasibility.” Researchers targeted economic variables such as the projected 10-year annualized cost for each technology tested, projected revenues from by-products, cost-share monies and incentives, and the impact an EST may have on the competitiveness of the state's pork industry compared to those in other states.

Candidate ESTs were analyzed in two phases. The Phase 1 report, issued in July 2004, reviewed eight ESTs. Two met the environmental performance standards — the Super Soils on-farm liquid technology and Orbit HSAD (high solids, anaerobic digester).

A year later, the Phase 2 report was filed, singling out three additional technologies that met the technical performance criteria. They included the Super Soils-Compost System; Gasifier (Re-Cycle) system; and Biomass Energy Sustainable Technology (BEST) Idaho fluidized bed combustion system.

The latter three systems and the Orbit HSAD (high solids, anaerobic digester) system are for the treatment of solids only, which must be coupled with a system that treats the liquid components (urine, flushed water/manure slurry) of the waste stream.

The Super Soils-liquid system was the only liquid system that met technical performance criteria. Table 1 offers additional details about the five candidate ESTs.

Cost Comparison Basis

To establish the economic values mandated in the agreement, researchers used the projected costs of retrofitting an existing lagoon-spray-field system with the ESTs, including the impact the technology would have on the competitiveness of the state's pork industry.

The unit cost for this analysis is based on the cost/1,000 lb. steady state live weight (SSLW)/year, on a 10-year annualized basis. (Table 1).

“The annualized cost ($/1,000 lb. SSLW/year) is a pretty good way to think about these technologies, because it's a cost per unit of capacity,” explains Kelly Zering, NCSU agricultural economist and project team leader.

For example, the value assigned to one head of finishing capacity is 135 lb. SSLW. Therefore, 1,000 lb. of finishing capacity, divided by 135, is 7.4 head. A sow in a farrow-to-wean system is 433 lb., so 1,000 lb. SSLW equals 2.3 sows; a nursery pig is 30 lb., so 1,000 lb. SSLW represents 33.2 nursery pigs.

The baseline, annualized cost of the typical lagoon-spray-field system in North Carolina is $86.81 (Table 2). The annualized, incremental cost in this table reflects the additional cost a producer would be expected to incur each year for 10 years, over and above what they were spending with the lagoon-spray-field system, explains Zering. Those costs could be reduced if energy and/or by-products of the technology could be sold.

“In brief, the collective economic data indicates the projected additional costs of retrofitting existing lagoon-spray-field farms with candidate ESTs for a complete treatment system (liquid and solid treatment) ranges from $90 to over $400 per unit cost,” Williams says.

By comparison, a permitted lagoon-spray-field system would have cost about $85 (per unit cost) in 2004. That figure has become a target for the technology suppliers, but it is important to recognize that an annualized incremental cost of $85 would result in a predicted 12% reduction in the state's herd size, Williams says.

“The clear message from the industry and agri-business representation is that a 12% reduction is unacceptable,” he says. “However, I think it is unreasonable to expect that anything that may have a (negative) impact on herd size is, by default, economically infeasible. My position is, if you accept a target or recommendation as reasonable, then that can and should be pursued with a policy and a timeline that minimizes the impact on herd size.”

For Zering, the question begging an answer is: “How much can we ask North Carolina farmers to spend to retrofit, and what would be the impact on the industry if we do that?”

Williams says the long-term impact of adopting the ESTs that currently meet performance standards could result in a 12-50% reduction in North Carolina's pork output.

“The agreement states that the companies (Smithfield Foods, Premium Standard Farms) will adopt the technologies that are determined to be economically feasible,” says Williams. “It also states that the companies acknowledge that the costs may be higher than the existing spray-field technology, as well as gives them the right to dispute the findings.”

Following is a more detailed explanation of the five candidate ESTs:

One Liquid EST Named

Super Soils — Liquid: This solids separation/nitrification-denitrification/soluble phosphorus removal/solids processing system was tested on a 4,000-head finishing site with six naturally ventilated barns equipped with pit fans and a pit recharge system.

The liquid portion of this technology that met the EST standards processed approximately 10,000 gal. of wastewater/day. The liquid waste stream flows between tanks in a circulating loop undergoing denitrification (anaerobic process) in one tank and nitrification (aerobic process) through the use of concentrated nitrifying bacteria in a second tank. The treated wastewater is stored and used for recharging pits. A portion is further treated for soluble phosphorus removal and irrigated fertilizer application.

“The Super Soils process primarily treats the waste to remove the solids by chemical application, which lowers the solids as well as the phosphorus. The liquid is then processed through nitrification-denitrification. Biologically, ammonia is first under an aerobic treatment process, with oxygen added for conversion to nitrate. Then, in simplistic terms, in the anaerobic environment, the nitrate is converted to harmless nitrogen gas. The process is similar to a small municipal waste treatment system,” Williams explains.

“They successfully did two things with their liquid treatment, initially. First, when they took out the solids, their process dropped the nutrient phosphorus out, so that removed one environmental variable of concern. Second, their approach also killed the pathogenic bacteria, meeting another performance standard,” he says.

In the first-generation technology, the data shows they were getting close to 100% reduction in the established performance criteria.

Williams says the Super Soils-Liquid technology looks like a tank farm, where the lagoon is replaced by a series of tanks.

Basically, it's a conglomeration of different technologies from around the world. “They combined these technologies to operate at a lower cost than the high-energy, high-oxygen content used by municipalities, which would be very, very cost prohibitive in the pork industry,” he says.

Still, the cost of the system tested stands at nearly $400 annualized incremental cost (Table 2). “The Super Soils group, with their second-generation project, are proposing to get the cost down close to $100,” Williams says.

The Super Soils-Liquid technology must be coupled with some type of solid separation treatment.

Four Solid ESTs Surface

The EST standards were met by four solid treatment systems. Three were pilot-sized projects with solids managed off the farm on a separate site and costs projected to full-scale operation. A fourth, the compost technology, was operated full scale and proposed to be an on-farm system.

The four solids treatment technologies included:

Orbit HSAD: The main component of this technology is an enclosed, high-temperature (thermophilic) anaerobic digester, which converts the solids portion of the waste stream into methane and carbon dioxide (biogas). This biogas is used as an alternative energy source to generate electricity or heat.

“Orbit is a 100% enclosed steel tank centralized treatment system. After the manure stream has undergone the separation process, the solids/slurry, 25-30% solids, is delivered to the digester, which looks like a large shipping crate,” says Williams. “It is designed to be compartmentalized, making it easy to add or remove capacity pretty easily.”

Solids spend 15-21 days in the digester, depending on loading rates (quantity, time) and waste stream components. Approximately 75% of the organic carbon is converted to biogas, with the remainder producing an effluent sludge. This sludge and the remaining solid fraction are further processed to make a value-added liquid fertilizer, a soil amendment or compost.

“The Orbit HSAD system generates methane, so the key to its success will depend on the capability to get a reasonable return on the energy (i.e. electricity) that's developed, and the fate of the digestate (slurry) after the energy has been extracted,” says Williams.

Theoretically, the energy can be routed back into the grid as electricity, although the market often depends on location and energy demand in an area.

Using the “cost/1,000 lb. SSLW/year” metric, the amount is estimated at $373.22, but the cost will vary depending on the solids concentration delivered.

Realistically, this is not an on-farm system, so it may not be fair to use that metric, Zering notes. More likely, a “tipping fee” would be charged based on quantity and solids percentage delivered. Municipal waste processors commonly charge tipping fees. “The technology supplier says the cost will be considerably less than $373/1,000 lb. SSLW,” he says.

“Our position was, if the technology provider gave us information to show that there was a market for one or more of their products, and they could sell all they wanted for an established price, then we would include that in the analysis,” says the NCSU economist. “It's reasonable to assume that you could sell all of the electricity that you could produce from hog farms in North Carolina, but when it comes to selling the compost or some other product, then the market becomes more localized — and we need some data to support those economics.”

To better establish the breakeven costs of the solids treatment systems, Zering and his colleagues also developed a sensitivity analysis to determine the impact solids separation rates would have on the annualized incremental costs, using the cost/1,000 lb. SSLW metric (Table 3).

“The cost/dry ton treated/processed serves as an indication of the breakeven value necessary to fully cover the process. Because this is a ‘dry ton treated’ figure, the cost of separation is not included,” he explains.

Using the Orbit system as an example, the cost/dry ton treated is $872.15, at the highest rate operated in the experiment. If the slurry were delivered at 25% solids, the cost/wet ton would be one-fourth of that amount, or $218.04. “That would be the tipping fee if you wanted to hold net costs at zero,” Zering explains. The cost/dry ton does not account for any revenues generated from added-value products.”

When analyzing the solid separation technologies, Zering thinks the cost/dry ton treated is better than the cost/1,000 lb. SSLW, because the latter is so dependent on the type of solids separation available.

“Some technologies capture 15% of the solids, while others capture well above 50%, so the cost/1,000 lb. SSLW is so conditional,” he says.

Returning to Table 3, Zering notes the actual moisture content of the solids used in the test, and the cost calculated/dry ton treated. The three columns to the right show the costs/dry ton converted to cost/1,000 lb. SSLW/year at three solids separation rates (low, medium, high).

“If you only get 0.15 dry tons/1,000 lb. SSLW, then you get a low cost/1,000 lb. SSLW, because you're just not getting much solids to process,” he continues.

The medium separation rate (0.43) in Table 3 was used for the predicted annualized incremental costs presented in Table 2.

At the high separation rate, where most of the solids are separated out of the waste stream, the costs/1,000 lb. SSLW go up, because there are more solids to process.

“If you ever get to the point where you are generating revenues from the solids, those costs are offset. Then, the more efficient you are, the more revenue you get,” Zering notes. “That is why the cost/dry ton processed is the best way to think about what it costs for each of the solids treatment systems.”

For perspective, it is also important to remember that a complete manure management package would require both liquid and solids processing. Therefore, combining the Super Solids-Liquid technology costs with Orbit solids processing delivered at 25% solids, the total annualized incremental cost/1,000 lb. SSLW would be roughly $618/year. Zering says the total could be lowered because the Super Soils-liquid expenditure includes some land application costs for the solids.

Naturally, variable costs may differ in other parts of the country. These are North Carolina costs and should be used as a reference point only, Zering says.

Super Soils-Compost System: This composting facility is a centralized site that receives separated solids from a 4,360-head finishing facility. The Super Soils-Compost technology mixes separated solids from swine manure system flow with bulking materials, such as wood chips or cotton gin by-products, daily.

When the composting process is complete, the product is placed in curing piles and allowed to stabilize. The cured product can be used for fertilizers and other soil amendment products.

The breakeven on this technology is $194.56 on a dry ton basis (Table 3). In the cost comparison, using the $/1,000 lb. SSLW and a medium separation rate, the annualized cost is a favorable $83.27. But, again, this cost would have to be combined with a liquid processing technology.

Gasifier (Re-Cycle): This gasifier system was located at NCSU's Animal & Poultry Waste Management Center, and utilized a belt system to deliver the solids to be gasified. The belt system cost is not included in Table 3. Any solids delivery system could be used.

In the pilot-scale experiment, solids at 50% moisture were loaded into the gasifier daily, and heated to nearly 1,500° F. “The percent moisture matters, because it affects the amount of fuel required to gasify the solids. The drier, the better,” Williams says.

The gasification process produces by-products: carbon monoxide, carbon dioxide, methane and ash. The ash could be used as a feed supplement or as a fertilizer amendment. The waste heat produced from the gasification process could be captured and utilized.

“I think the gasifier approach is a very logical way to handle manure solids, because it reduces the volume dramatically; plus you get an energy product,” he says.

The annualized cost metric is $76.33/1,000 lb. SSLW, excluding use of the energy. The projected breakeven is $178.35/dry ton.

BEST-Idaho: The solids from two BEST test farms, 3,000- and 4,000-head finishers, respectively, were blended with turkey litter and trucked to a combustion facility in Coeur d' Alene, ID, for evaluation.

“To get the moisture content of the solids correct, it was blended with poultry litter,” Williams notes.

The combustion and emissions characteristics of the manure solids-litter mixture were evaluated in an atmospheric bubbling, fluidized bed system maintaining a bed temperature above 1,300° F.

“This technology also uses high-temperature combustion. The BEST-Idaho system, however, relies on an aerobic, fluid-on-vent combustion process. And like the anaerobic gasification process, this technology extracts energy from the solids, reducing the content to ash. The heat is captured to turn a turbine or generate steam to power a feedmill, an ethanol plant or a similar application.”

The breakeven on this technology, using the dry ton basis, is $597.38. In the cost comparison, using the $/1,000 lb. SSLW and a medium separation rate, the annualized cost is $255.68.

Closing Thoughts

Williams sees the multi-year project to identify environmentally superior technologies as an opportunity to answer some energy-dependence questions.

“This is an opportunity to take what has been demonstrated technically, and pursue over a reasonable amount of time some of the incentives that could be very favorable to pork producers who want to incorporate these technologies and provide energy by-products as a result,” says Williams. “I think government incentives will be critical to making these technologies work.

“Various sources of financial support, including cost-share programs, may be available in the future, with the most promising opportunities for technologies that generate energy,” he adds.

“These are technologies that people, are not familiar with,” Zering says. “I think we did the best we could to actually measure the costs to build and operate (these technologies).

“We think there is some new information about the cost to put these systems on the farm and operate them,” he continues. “It boils down to — how much capital will I have to come up with to finance, put in place and operate a system on a day-to-day basis?

“I think different parts of the country — different parts of the world — will utilize different combinations of treatments. In some places, water is very valuable, so they might not want to just allow it to evaporate or spray it on fields where it's not utilized by plants. In the Midwest, plant nutrients are very important. In other parts of the world, energy is more valuable, so capturing it and utilizing it will be the highest priority,” Zering concludes.

Editor's note: Phase 1 & 2 Technology Determination reports, technology descriptions and additional information generated through the “Development of Environmentally Superior Technologies for Swine Waste management” initiative can be found at:

ESTs Explained

An environmentally friendly technology (EST) is “any technology, or combination of technologies, that 1) is permittable by the appropriate government authority; 2) is determined to be technically, operationally and economically feasible for an identified category or categories of farms as described in the agreements; and 3) meets the following performance standards:

  • “Eliminates the discharge of animal waste to surface waters and groundwater through direct discharge, seepage or runoff;

  • “Substantially eliminates atmospheric emissions of ammonia;

  • #8220;Substantially eliminates the emission of odor that is detectable beyond the boundaries of the parcel or tract of land on which the swine farm is located;

  • “Substantially eliminates the release of disease transmission vectors and airborne pathogens; and

  • “Substantially eliminates nutrient and heavy metal contamination of soil and groundwater.”

Table 1: Comparison of Candidate Technologies, Experimental Conditions and Invoiced Costs
Technology Super Soils Liquid Orbit HSAD3 Super Soils Composting BEST Idaho Combustion Gasifier Re-Cycle
Pilot or Full Scale Full Pilot Full Pilot Pilot
Complete or Incomplete System Complete On-farm Incomplete Off-farm Complete Off-farm Incomplete Off-farm Incomplete Off-farm
Type of Farm Served Feeder-Finish N/A N/A N/A N/A
Capacity, head 4,360 N/A N/A N/A N/A
SSLW1 Capacity Served (lb.) 588,600 N/A N/A N/A N/A
% of Capacity Occupied During Experiment 85% N/A N/A N/A N/A
Solids Processing Rate N/A 660 - 2,200 lb./day @ ~25% DM4 68,750 lb./week @ 16.7% DM 739 lb./hr. @ 30 to 60% DM 18 to 30 lb./hr. @ 48 to 79% DM
Duration of Experiment 11 months 4 months 6.5 months 15 days 2 trials
Total Installed Cost (APWMC2 Invoices+Other) $1,041,621 $805,848 $210,663 Not Reported Not Reported
Type of Manure Removal Pit N/A N/A N/A N/A
Reported Volume of Barn Effluent/Day/1,000 lb. SSLW of Capacity 19.14 N/A N/A N/A N/A
1SSLW = steady state live weight
2APWMC = Animal & Poultry Waste Management Center, North Carolina State University
3HSAD = high solids, anaerobic digester
4DM = dry matter content
Table 2. Predicted Annualized Incremental Costs1 (Task 1) of the EST Candidate Technologies
Technology Annualized Cost1 ($/1,000 lb. SSLW/year)
Baseline (lagoon and spray-field) $86.81
On-Farm Complete Systems Annualized Incremental Cost1 ($/1,000 lb. SSLW/year)
Barham Farm4 $89.17
Environmental Technologies (Sustainable NC-Frontline Farmers)4 $136.70
Re-Cip4 Solids Separation Reciprocating Wetlands $143.21
Super Soils - Liquid $399.71
Separated Solids Treatment Systems (Add-On Technologies)2, 3 (assumes 0.43 dry tons of solids collected/1,000 lb. SSLW/year) Annualized Incremental Cost1 ($/1,000 lb. SSLW / year)
BEST Idaho (centralized fluidized bed combustion facility) $255.68
Gasifier (Re-Cycle) $76.33
Orbit High Solids Anaerobic Digester $373.22
Super Soils Composting Facility $83.27
1Annualized costs as shown in this table are calculated for a 4,320-head finishing farm using a pit-recharge system of manure removal and nitrogen-based land application to forages.
2The annualized incremental costs for the solids treatment technologies include the avoided cost of on-farm land application of solids. That is, ($/1,000 lbs. SSLW/yr.) = ($/dry ton technology cost - $/dry ton avoided land application cost)* (dry tons of solids/1,000 lbs. SSLW/yr.). By accounting for avoided land application costs, the incremental annualized costs for the solids treatment systems can be added directly to the incremental annualized costs for complete on-farm systems (which include the cost of land-applying solids).
3See separate technology reports for additional analysis of breakeven prices for product sales.
4Manure management technologies “on the bubble.”
Table 3. Sensitivity Analysis on Solids Treatment Systems: The Impact of Solids Separation Rate on Annualized Incremental Costs ($/1,000 lb. SSLW/year)
Technology Moisture Content of Solids1 (%) $/Dry Ton2 Treated/Processed Low Separation Rate3 Medium Separation Rate4 High Separation Rate5
(0.15 dry tons of solids/1,000 lb. SSLW/yr.) (0.43 dry tons of solids/1,000 lb. SSLW/yr.) (1.14 dry tons of solids/1,000 lb. SSLW/yr.)
$/1,000 lb. SSLW/yr.
BEST Idaho 70% $597.38 $89.31 $255.68 $680.42
Gasifier (Re-Cycle) 50% $178.35 $26.75 $76.33 $203.14
Orbit HSAD 70% $872.15 $130.82 $373.28 $993.38
Super Soils-Compost 83% $194.56 $29.18 $83.27 $221.60
Note: These costs are based on demonstrated performance and cost data (usually from pilot-scale or prototype systems). Solids treatment technology providers have proposed steps to reduce the costs of these systems in future generations of their technologies. All of these solids treatment technologies also have an associated proposed by-product revenue stream. If product revenue exceeds breakeven prices for solids treatment, the incremental cost of solids treatment could become negative; that is, a net revenue. See the Task 1 Final Reports for these technologies for detailed breakeven analyses, a discussion of potential revenue streams, and the costs and returns of proposed next-generation solids treatment systems.
Note: The numbers in boldface (medium separation rate) represent the numbers that are reported in the Task 1 summary table for solids treatment technologies.
1Moisture content of separated solids has a significant effect on the cost/dry ton of solids treatment systems. The costs reported in this table assume the moisture content that is listed in this column. Changing this assumption changes the predicted costs reported in this table.
2The costs in this column reflect the per-dry-ton technology cost minus the avoided per-dry-ton cost of on-farm land application of solids.
3Low separation rate corresponds to performance data collected from the BEST FAN + TFS separator as operated at Corbett Farm #1. Among the Environmentally Superior Technologies (EST) separators, the EKOKAN separator had the lowest modeled separation rate at 90 dry lb. of solids (0.045 dry tons)/1,000 lbs. SSLW/yr.
4Medium separation rate corresponds to performance data collected from the Environmental Technologies, Inc. separator as operated at Chuck Stokes Farm.
5High separation rate corresponds to performance data collected from the Super Soils separator as operated at Goshen Ridge Farm. Among the EST separators, the belt system had the highest modeled separation rate at 2,990 dry lb. of solids (1.495 dry tons)/1,000 lb. SSLW/yr.

Technologies ‘On the Bubble’

There are a few technologies that are very, very close to making the cut,” Williams emphasizes. A soon-to-be released Phase 3 report will contain recommendations to technology providers that are “on the bubble,” providing them an opportunity to make adjustments and be reconsidered.

One such technology, a covered, anaerobic lagoon that operates at ambient temperatures, was tested at the 4,000-sow, farrow-to-wean farm owned by Julian Barham, Zebulon, NC. “They met the criteria for all parameters, except the ammonia emissions,” Williams explains.

Another is the Environmental Technologies' closed-loop, liquid treatment system. “I consider them on the bubble because the economics are comparatively better, and they are very, very close on a couple of the environmental parameters,” he says.

Finally, the Re-Cip solids separation, reciprocating wetlands system shows promise. This technology, tested on a 2,000-head finishing unit, features cells or basins in which alternating anaerobic and aerobic conditions are created to remove nitrogen from the swine waste stream. “The economics, comparatively, are much better than the Phase 1 Super Soils technology,” Williams says. “The only environmental parameter that did not meet requirements was the pathogens, so they may be able to make adjustments for that.”