Progress 10/01/01 to 09/30/07
Outputs
Outputs included field days and visits to research/demonstration sites for several projects which were included in the Smithfield Foods, Inc./NC Attorney General projects for evaluating alternative manure treatement systems for meeting critieria as Environmentally Superior Technology. The Technical Advisory Board for the "Smithfield Projects" visited various sites where there were aerated biofilters, wetlands treatment, covered earthen digesters, belt for collection of manure and separating urine, and a sequencing batch reactor. Dissemination of the reports for these projects was by posting on the web site of the Animal and Poultry Waste Management Center at NC State University. Other outputs of research on this project was two patents issued for method and for apparatus for forming struvite from wastewater for removing phosphorus.
Impacts
The research/demonstration of alternative manure treatment technologies resulted in documentation of technical performances that can be used for evaluating options for manure treatment. This performance information along with the cost information was used to determine whether the technologies met the criteria of Environmentally Superior Technologies under the terms of the agreement between Smithfield Foods, Inc. and the NC Attorney General. One wastewater treatment system and four solids treatment systems were designated to meet the environmental criteria, but not the cost criteria. This demonstrated the challenges in obtaining treatment that meet high environmental standards as well as being econimically viable. This has resulted in further legistation by the state legislature to provide cost sharing to continue to evaluate alternative technologies.
Publications
- Westerman, P. W., J. Arogo Ogejo, G. L. Grabow and M. E. Adcock. 2006. Swine anaerobic lagoon nutrient concentration variation with season, lagoon level, and rainfall. Presented at 2006 ASABE International Meeting, Portland, OR, 9-12 July 2006. ASAE Paper No. 064146. ASAE, St. Joseph, MI 9 pg.
- Journal Articles Shah, S. B., G. L. Grabow and P. W. Westerman. 2006. Ammonia desorption in five types of flexible tubing materials. Applied Engineering in Agriculture 22(6):919-923.
- Shah, S. B., P. W. Westerman and J. Arogo. 2006. Measuring ammonia concentrations and emissions from land and liquid surfaces: A review. J. Air & Waste Manage. Assoc. 56(7):945-960.
- Conference Papers and Proceedings Koleva, M., J. Cheng, R. Arsov, and Y. Topalova (2006) Possibilities for Implementation of the CANON Technology for Biological High Strength Nitrogen Removal. Proceedings of the 11th Scientific and Practical Conference "Water Quality Technologies and Management in Bulgaria", 22-23 February 2006, Sofia, Bulgaria, pp141-150.
- Book Chapters Arogo, J., P. W. Westerman, A. J. Heber, W. P. Robarge, and John J. Classen. 2006. Ammonia emissions from animal feeding operations. In: Animal Agriculture and the Environment: National Center for Manure and Animal Waste Management White Papers, p. 41-88. Edited by J. M. Rice, D. F. Caldwell, and F. J. Humenik. ASABE, St. Joseph, MI. 776 pages
- Sweeten, J. M., L. D. Jacobson, A. J. Heber, D. R. Schmidt, J. C. Lorimor, P. W. Westerman, J. R. Miner, R. H. Zhang, C. M. Williams, and B. W. Auvermann. 2006. Odor mitigation for concentrated animal feeding operations: white paper and recommendation. In: Animal Agriculture and the Environment: National Center for Manure and Animal Waste Management White Papers, p. 721-758. Edited by J. M. Rice, D. F. Caldwell, and F. J. Humenik. ASABE, St. Joseph, MI. 776 pages
- Peer Reviewed Extension Publications Shah, S., P. Westerman and J. Parsons. 2006. Poultry Litter Amendments. NC Extension Bulletin AG-657. North Carolina Cooperative Extension Service, North Carolina State University, Raleigh, NC. 2 pg. http://www.bae.ncsu.edu/programs/extension/publicat/wqwm/poultry/fact sheet_agw-657short.pdf
- Shah, S., P. Westerman and J. Parsons. 2006. Poultry Litter Amendments. NC Extension Bulletin AGW-657. North Carolina Cooperative Extension Service, North Carolina State University, Raleigh, NC. 8 pg. http://www.bae.ncsu.edu/programs/extension/publicat/wqwm/poultry/fact sheet_agw-657long.pdf
- Patents Bowers, Keith E. and Philip W. Westerman. 2006. Apparatus for removing phosphorus from waste lagoon effluent. US Patent Number 6,994,782. Issued Feb. 7, 2006. US Patent and Trademark Office, Alexandria, VA.
- Bowers, Keith E. and Philip W. Westerman. 2006. Method for removing phosphorus from waste lagoon effluent. US Patent Number 7,005,072. Issued Feb. 28, 2006. US Patent and Trademark Office, Alexandria, VA.
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Progress 10/01/05 to 09/30/06
Outputs
Several alternative swine manure management systems or technologies have been evaluated in N. C. Most of these systems were evaluated on swine farms, and some were pilot scale or lab scale systems. A poster with an overview of several of the evaluations was prepared for an international conference showing the environmental criteria used and the relative costs of the various systems or technologies. Essentially, all the systems that were evaluated were determined to be too expensive to implement on farms. The inhibition effects of high potassium concentration on thermophilic anaerobic digestion of swine waste were studied. A continuous stirred tank reactor (CSTR) operated at a hydraulic retention time (HRT) of 10 days and a chemical oxygen demand (COD) loading of 7.2-7.5 g/L/day was used to digest swine waste and cultivate thermophilic anaerobic microorganisms. To evaluate the toxicity of potassium, batch inhibition tests were also conducted. Without acclimation to
potassium, the inhibition threshold beyond which methane production decreased significantly was 3 g K/L. Volatile fatty acids accumulation was observed during the decline of methane production. Propionic acid was the dominant fatty acid, indicating propionic acid utilizers were more sensitive to potassium inhibition than acetoclastic methanogens. Acclimation to 6 g K/L increased the tolerance of anaerobic inocula to potassium inhibition without significantly reducing the methanogenic activity. Inhibition threshold was increased from 3 g K/L for unacclimated inocula to 6 g K/L for inocula acclimated to 6 g/L of potassium. Emission of ammonia and hydrogen sulfide from an anaerobic swine waste treatment lagoon and a fan-ventilated swine confinement building were measured continuously for a few days in each season over a one-year period. Ammonia nitrogen emissions measured with a small chamber floating in the lagoon showed seasonal average emission rates ranging from about 1,000 to over
4,000 microgram per square meter per minute for winter and summer, respectively. Hydrogen sulfide emissions were less by 3 to 4 orders of magnitude. Average seasonal emission rates from the barn in units of grams per day per 500 kg live weight were 12 to 24 for ammonia nitrogen, and 1.4 to 4.3 for hydrogen sulfide.
Impacts
Intensive livestock production presents challenges for preventing air and water quality degradation. Concerns include odor, ammonia emission, and nutrient management. It is important to demonstrate and evaluate alternative systems in pilot-scale and full-scale before they can be recommended for farmers. Livestock producers need more management options to address the environmental concerns, but the management options need to be reasonable in costs and management requirements, and clearly show environmental improvements. The evaluations of alternatives for swine manure management in N. C. should have application for other states that raise swine.
Publications
- Blunden, J., V. P. Aneja and P. W. Westerman. 2006. Measurement and analysis of ammonia and hydrogen sulfide emissions from an anaerobic swine waste treatment lagoon and confinement building in North Carolina. In: Proceedings of the Workshop on Agricultural Air Quality: State of the Science, p. 71-79. June 5-8, 2006, Potomac, MD.
- Chen, Y. and J.J. Cheng. 2006. Application of anaerobic processes. Water Environment Research. 78(10), 1363-1385.
- Westerman, P., J. Classen, M. Williams, and K. Zering. 2006. Overview of evaluations of alternative swine manure treatment systems in North Carolina, USA. In: (Ed. Soren Petersen) Proceedings of the 12th RAMIRAN International Conference, Technology for Recycling of Manure and Organic Residues in a Whole-Farm Perspective, Vol. II, p. 13-15, Aarhus, Denmark, Sept. 11-13.
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Progress 10/01/04 to 09/30/05
Outputs
Several alternative swine manure management systems or technologies are being evaluated in N. C. Most of these systems are being evaluated on swine farms, and some are pilot scale or lab scale systems. Evaluation of two solids/liquid separation systems for flushed swine manure were published in a journal. The two systems were: 1) a screw-press separator (FAN) followed by tangential flow gravity-settling tanks (TFS system), and 2) a screen and screw-press separator (Filtramat) followed by TFS system. Input to the separation systems typically had 0.5% to 1.0% total solids. As a percentage of input to the systems, the recoveries in separated solids were about 10% for total solids, about 10% to 20% for suspended solids, and about 1% and 4% for nitrogen and phosphorus, respectively. The recovery of moist solids (70 % moisture) per unit of flow was variable and averaged about 3 to 4 kg per cubic meter (25 to 33 lb per 1000 gal.). The moist separated solids averaged about
0.5% nitrogen and 0.1% to 0.2% phosphorus. Although concentration reductions through the total system did not agree well with the mass recoveries, the concentration reductions through the TFS systems were similar for the two sites, and showed 40% to 60% reductions for suspended solids, phosphorus and several other parameters. Concentration reductions through the FAN and Filtramat components were 13% and 6% for total solids, respectively. Another technology evaluation for centrifuge removal of solids and phosphorus from flushed swine manure or lagoon sludge was reported in a conference paper. The centrifuge removed about 50 percent of phosphorus without adding chemicals, but could remove up to 80 percent with addition of chemicals.
Impacts
Intensive livestock production presents challenges for preventing air and water quality degradation. Concerns include odor, ammonia emission, and nutrient management. It is important to demonstrate and evaluate alternative systems in pilot-scale and full-scale before they can be recommended for farmers. Livestock producers need more management options to address the environmental concerns, but the management options need to be reasonable in costs and management requirements, and clearly show environmental improvements. The evaluations of alternatives for swine manure management in N. C. should have application for other states that raise swine.
Publications
- Westerman, P. W. and J. Arogo. 2005. On-farm performance of two solids/liquid separation systems for flushed swine manure. Applied Engineering in Agriculture 21(4):707-717.
- Westerman, P. W. and J. Arogo Ogejo. 2005. Centrifuge solids/liquid separation of swine flushed manure and lagoon sludge. Presented at 2005 ASAE International Meeting, Tampa, FL, 17-20 July 2005. ASAE Paper No. 054090. ASAE, St. Joseph, MI 12 pg.
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Progress 10/01/03 to 09/30/04
Outputs
Several alternative swine manure management systems or technologies are being evaluated in N. C. Most of these systems are being evaluated on swine farms, and some are pilot scale or lab scale systems. Evaluation of two solids/liquid separation systems were completed for flushed swine manure: a screw-press separator (FAN) followed by tangential flow gravity-settling tanks (TFS system), and a screen and screw-press separator (Filtramat) followed by TFS system. Input to the separation systems typically had 0.5% to 1.0% total solids. As a percentage of input to the systems, the recoveries in separated solids were about 10% for total solids, about 10% to 20% for suspended solids, and about 1% and 4% for nitrogen and phosphorus, respectively. The recovery of moist solids (70 % moisture) per unit of flow was variable and averaged about 3 to 4 kg per cubic meter (25 to 33 lb per 1000 gal.). The moist separated solids averaged about 0.5% nitrogen and 0.1% to 0.2% phosphorus.
Although concentration reductions through the total system did not agree well with the mass recoveries, the concentration reductions through the TFS systems were similar for the two sites, and showed 40% to 60% reductions for suspended solids, phosphorus and several other parameters. Concentration reductions through the FAN and Filtramat components were 13% and 6% for total solids, respectively. The Ekokan LLC waste treatment system consists of solids/liquid separation and biofiltration of the liquid with upflow aerated biological filters. Flushed waste flows through a solids-liquid separator and then is pumped to an equalization tank. Liquid flows from the equalization tank by gravity and passes through first-stage and second-stage aerated biofilters connected in series (two sets, or four biofilters in total), with each biofilter having 130 m3 of plastic media in a 151 m3 (40,000 gal.) tank. Overall, the aerated biofilters demonstrated potential for greater than 90% reduction of
ammonia in spring season, resulting in relatively high concentrations of nitrite plus nitrate nitrogen in biofilter effluent (170 to 300 mg/L). Continuous aeration of the biofilters resulted in an energy use of about 2,100 kWh/d.
Impacts
Intensive livestock production presents challenges for preventing air and water quality degradation. Concerns include odor, ammonia emission, and nutrient management. It is important to demonstrate and evaluate alternative systems in pilot-scale and full-scale before they can be recommended for farmers. Livestock producers need more management options to address the environmental concerns, but the management options need to be reasonable in costs and management requirements, and clearly show environmental improvements. The evaluations of alternatives for swine manure management in N. C. should have application for other states that raise swine.
Publications
- Westerman, P. W. and J. Arogo. 2004. EKOKAN biofiltration technology performance verification. In: Development of Environmentally Superior Technologies: Phase I Report for Technology Determination per Agreements Between the Attorney General of North Carolina and Smithfield Foods, Premium Standard Farms and Frontline Farmers, Appendix A.6. 85 pg. A&PWMC, NC State University, Raleigh, NC.
- Westerman, P. W. and J. Arogo. 2004. Biomass energy sustainable technology performance verification (solids/liquids separation). In: Development of Environmentally Superior Technologies: Phase I Report for Technology Determination per Agreements Between the Attorney General of North Carolina and Smithfield Foods, Premium Standard Farms and Frontline Farmers, Appendix A.2. 88 pg. A&PWMC, NC State University, Raleigh, NC.
- Westerman, P. W. and J. Arogo. 2004. On farm performance of two solids/liquid separation systems for flushed swine manure. ASAE Paper No. 044073. Written for presentation at the 2004 ASAE/CSAE Annual International Meeting, Ottawa, Ontario, Canada, Aug. 1-4. 19 pg. ASAE, St. Joseph, MI.
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Progress 10/01/02 to 09/30/03
Outputs
Alternative swine manure management systems are being evaluated in N. C. Most of these systems are being evaluated on swine farms, and some are pilot scale or lab scale systems. Two solids/liquid separation systems were evaluated for flushed swine manure: a screw-press separator (FAN) followed by tangential flow gravity-settling tanks (TFS system), and a screen and hydraulic press separator (Filtramat) followed by TFS system. Approximately 36,000 kg of wet solids (about 68 % moisture) were collected in large bags during May through July 2003, and trucked to EPI in Idaho for combustion testing. Initial combustion tests indicated that a 3:1mixture of turkey litter and separated swine solids combusted adequately producing a good ash product. The Ekokan LLC waste treatment system consists of solids/liquid separation and biofiltration of the liquid with upflow aerated biological filters. Flushed waste flows through a solids-liquid separator and then is pumped to an
equalization tank. Liquid flows from the equalization tank by gravity and passes through first-stage and second-stage aerated biofilters connected in series (two sets, or four biofilters in total), with each biofilter having 130 m3 of plastic media in a 151 m3 (40,000 gal.) tank. Data showed 90% or more TAN reduction during May-June, 2003. Organics destruction and nutrient uptake in an integrated pilot system of anaerobic digestion and duckweed nutrient removal for swine wastewater treatment were monitored under field conditions. Raw swine wastewater of 100 gallons/day was first treated in a 1,000-gallon anaerobic digester with floating ballast rings. Duckweed (Lemna gibba 8678) was grown in three 1,000-gallon tanks to recover nutrients from the anaerobic effluent. The duckweed was periodically harvested and can be used as animal, poultry, and fish feed. The overall removals through the entire system was 90 % for COD, 70 % for N, and 75 % for P. A belt-based housing system was
evaluated for approximately 100 grow-finish pigs. The belt system works well for collecting dry fecal stream (50% DM) and results in a substantial reduction in ammonia emission (6.5% of feed nitrogen). A project is in progress to identify the sources of airborne emissions from swine houses. Trials to date show that animal and/or floor surface is source of phenolics/VFA. Alkanes are from pit. Ammonia is from floor and pit (50/50), and methane is from animal only. Together with the DIAS (Danish institute of animal science), the source of odor will be more closely examined (slats vs. animal).
Impacts
Intensive livestock production presents challenges for preventing air and water quality degradation. Concerns include odor, ammonia emission, and nutrient management. It is important to demonstrate and evaluate alternative systems in pilot-scale and full-scale before they can be recommended for farmers. Livestock producers need more management options to address the environmental concerns, but the management options need to be reasonable in costs and management requirements, and clearly show environmental improvements. The evaluations of alternatives for swine manure management in N. C. should have application for other states that raise swine.
Publications
- Westerman, P. W., J. Arogo, A. Kantardjieff and P. Kantardjieff. 2003. Evaluation of Ekokan biofiltration treatment system on a swine farm. ASAE Annual International Meeting, July 27-30, 2003, Las Vegas, NV. ASAE Paper No. 03-4125. ASAE, St. Joseph, MI.
- Westerman, P. W. and J. Arogo. 2003. Ekokan upflow biofiltration treatment system. In: Proceedings of the North Carolina Animal Waste Management Workshop, p. 26-29, October 16-17, Research Triangle Park, NC. N. C. St. University, Raleigh, NC.
- Westerman, P. W., J. Arogo, G. Boyd and K. Elmer. 2003 Evaluation of the "BEST" system - solids/liquid separation and solids combustion. In: Proceedings of the NCSU Animal Waste Management Conference, p. 54-61, October 16-17, 2003, Research Triangle Park, NC. N. C. State University, Raleigh, NC.
- Chaiprapat, S., J. Cheng, J. J. Classen, J. J. Ducoste and S. K. Liehr. 2003. Modeling nitrogen transport in duckweed pond for secondary treatment of swine wastewater. Journal of Environmental Engineering 129(8):731-739.
- Carter, S. D., G. L. Cromwell, P. W. Westerman, J. S. Park and L. A. Pettey. 2003. Prediction of nitrogen, phosphorus, and dry matter excretion by swine based on diet chemical composition, feed intake, and nutrient retention. In: Proceedings of the 9th International Symposium on Animal, Agricultural and Food Processing Wastes, p. 285-295, October 12-15, Research Triangle Park, NC. ASAE, St. Joseph, MI.
- Cheng, J., S. Liehr and C. Lyerly. 2003. Swine wastewater treatment in an integrated system of anaerobic digestion and duckweed nutrient removal. ASAE Annual International Meeting, July 27-30, 2003, Las Vegas, NV. ASAE, St. Joseph, MI.
- Sweeten, J., L. Jacobson, A. Heber, D. Schmidt, J. Lorimor, P. Westerman, J. R. Miner, R. Zhang, C. M. Williams and B. W. Auverman. 2003. Odor mitigation for concentrated animal feeding operations: White paper and recommendations. In: Proceedings of AWRA 2003 Spring Specialty Conference Agricultural Hydrology and Water Quality. May 12-14, 2003, Kansas City, MO. AWRA, Middleburg, VA.
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Progress 10/01/01 to 09/30/02
Outputs
Alternative swine manure management systems are being evaluated in N. C. Systems include: (1) aeration (fine bubble diffusion) pond treatment of anaerobic lagoon effluent (50,000 gal./day) and recycle for flushing manure to the anaerobic lagoon (2) centrifuging flushed swine manure to remove solids and nutrients, (3) recovery of ammonia from swine lagoon effluent with ammonia stripping tower and condenser, (4) a covered anaerobic earthen digester with biogas utilization, nitrification biofilters, and utilization of effluent for greenhouse tomatoes, (5) a sequencing batch reactor for nitrification and denitrification, (6) removal of swine manure solids and combustion for energy recovery and utilization of ash minerals for diet supplements, (7) solids/liquid separation and liquid treatment in upflow aerated biofilters, and (8) a convex belt system for draining liquids and collecting manure solids from the barn for further processing by black soldier fly larvae to
produce a feed supplement (larvae), or other options. Most of these systems are being evaluated on swine farms, and some are pilot scale or lab scale systems. A trickling nitrification biofilter was operated to nitrify swine wastewater and then used as fertilizer and irrigation water for growing tomatoes in greenhouse. Ammonium in the influent was efficiently converted (almost 90%) to nitrate in the biofilter. There was seasonal effect on nitrification efficiency in the biofilter. Nitrogen and phosphorus removal from anaerobically pretreated swine wastewater by growing Spirodela punctata 7776, a promising duckweed identified in previous studies, has been investigated in outdoor tanks. Observed nitrogen and phosphorus removal rates in this study were as high as 2.32 and 0.51 g/m2-day, respectively. Nutrient concentrations in the wastewater and seasonal climate conditions had direct impacts on the duckweed growth and nutrient removal. The rate of duckweed production was 10.9 and 14.5 g
dry weight/m2-day during the summer and fall tests, respectively. A mathematical model was developed to describe nitrogen transport in duckweed-covered static ponds for nutrient recovery from swine lagoon water. A finite difference technique was used to solve the partial differential equations describing the ammonia transport and concentration in the pond. Laboratory testing was conducted with Spirodela punctata 7776, a duckweed strain, to calibrate the model. The performance of various solid separation systems will be tested under identical conditions under the USEPA Environmental Technology Program (ETV), available at http://www.epa.gov/etv/. One of the areas of concern in the program is source water protection that is being managed by NSF International (http://www.nsf.org/). Under this program a test plan has been developed to verify the separation performance of different technologies on a mass basis. The types of systems tested or under consideration include a centrifuge, sloped
screen, clarifier and press, and a sand filter.
Impacts
Intensive livestock production presents challenges for preventing air and water quality degradation. Concerns include odor, ammonia emission, and nutrient management. It is important to demonstrate and evaluate alternative systems in pilot-scale and full-scale before they can be recommended for farmers. Livestock producers need more management options to address the environmental concerns, but the management options need to be reasonable in costs and management requirements, and clearly show environmental improvements. The evaluations of alternatives for swine manure management in N. C. should have application for other states that raise swine.
Publications
- Chaiprapat, S., J. Cheng, J.J. Classen, and S.K. Liehr. 2002. Role of internal nutrient storage in duckweed for secondary swine wastewater treatment. Proceedings of 2002 ASAE Annual International Meeting / CIGR XVth World Congress, July 28-31, 2002, Chicago, Illinois, USA. Paper No. 02-4130.
- Cheng, J., J. Pace, M.M. Peet, D.H. Willits, and T. Shearin. 2001. Using a greenhouse tomato crop to recover the nutrients from swine wastewater. Proceedings of the International Symposium Addressing Animal Production and Environmental Issues, October 3-5, 2001, Research Triangle Park, North Carolina, USA.
- Cheng, J., M.M. Peet, D.H. Willits, and J. Pace. 2001. Integrated farming for sustainable agriculture. Proceedings of the International Conference for Agricultural Science and Technology, November 7-9, 2001, Beijing, China.
- Cheng, J., L. Landesman, B.A. Bergmann, J.J. Classen, J.W. Howard, and Y.T. Yamamoto. 2002. Nutrient removal from swine lagoon liquid by Lemna minor 8627. Transactions of the ASAE 45(4):1003-1010.
- Cheng, J. and B. Liu. 2002. Swine wastewater treatment in anaerobic digesters with floating medium. Transactions of the ASAE 45(3): 799-805. Cheng, J., B.A. Bergmann, J.J. Classen, A.M. Stomp, and J.W. Howard. 2002. Nutrient recovery from swine lagoon water by Spirodela punctata. Bioresource Technology 81(1): 81-85.
- De Visscher, A., L. A. Harper, P. W. Westerman, Z. Liang, J. Arogo, R. R. Sharpe and O. Van Cleemput. 2002. Ammonia emissions from anaerobic swine lagoons: Model development. Journal of Applied Meteorology 41:426-433.
- Hill, V. R., A. Kantardjieff, M. D. Sobsey and P. W. Westerman. 2002. Reduction of enteric microbes in flushed swine wastewater treated by a biological aerated filter and UV radiation. Water Environ. Res. 74(1):91-99.
- Howard, J.W., J. Cheng, B.A. Bergmann, and J.J. Classen. 2002. Nutrient removal from anaerobically pretreated swine wastewater with growing duckweed: pilot study. Proceedings of the IWA 3rd World Water Congress, April 7-12, 2002, Melbourne, Australia.
- Liang, Z. S., P. W. Westerman and J. Arogo. 2002. Modeling ammonia emission from swine anaerobic lagoons. Transactions of the ASAE 45(3):787-798.
- Sweeten, J. M., L. Jacobson, A. J. Heber, D. Schmidt, J. Lorimor, P. Westerman, J. R. Miner, R. Zhang, M. Williams and B. W. Auverman. 2001. Odor mitigation for concentrated animal feeding operations. White paper sponsored by the National Center for Manure and Animal Waste Management, Published by MWPS (also available on CD), Ames, IA. 50 pg.
- Westerman, P. W. and J. R. Bicudo. 2002. Application of mixed and aerated pond for nitrification and denitrification of flushed swine manure. Applied Engineering in Agriculture 18(3):351-358.
- Westerman, P. W. and J. R. Bicudo. 2002. Management strategies for organic waste use in agriculture. Invited presentation for the 10th International Conference of the European Research Network on Recycling of Agricultural, Municipal and Industrial Residues in Agriculture "RAMIRAN 2002", May 14-18, Strbske Pleso, Slovak Republic.
- Westerman, P. W. and J. Arogo. 2002. Performance of the IESS biokinetic air waste treatment system on a swine farm. ASAE Paper No. 02-4155, ASAE Annual International Meeting, July 28-31, Chicago, IL.
- Chaiprapat, S., J. Cheng, J.J. Classen, and S.K. Liehr. 2001 Modeling Nitrogen Transfer in Duckweed Covered Pond for Secondary Treatment of Swine Wastewater. Proceedings of the International Symposium Addressing Animal Production and Environmental Issues, October 3-5, 2001, Research Triangle Park, North Carolina, USA.
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