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Moody L.B.,Fertilizer Institute | Burns R.T.,University of Tennessee at Knoxville | Bishop G.,University of Tennessee at Knoxville | Sell S.T.,Iowa State University | Spajic R.,Agrokor Belje
Applied Engineering in Agriculture | Year: 2011

There has been an increasing interest in manure anaerobic digestion; however, economic constraints are still one of the limits to widespread use of the technology in the United States. Co-digestion of manure with other feedstocks has been noted as a way to increase the economic feasibility of animal feeding operation anaerobic digesters via increased energy production potential. A wide variety of materials have been proposed as co-digestion materials, and additional substrates will continue to receive consideration. Biochemical methane potential assays (BMPs) have been reported to provide a "firstcut" evaluation of potential substrates. This article provides specific details about the BMP assay process used by the Agricultural Waste Management Laboratory (AWML) at Iowa State University (ISU) on agricultural materials and by-products, including the assay method and utilization of the results. Additionally, BMP results from 31 samples assayed in the ISU AWML as broader anaerobic digestion research or as service to the industry have been included. Results showed that the high solid content and non-homogeneity of agricultural materials and by-products can increase variability in assay results. The method utilized here helped limit the effects by utilizing volatile solids concentrations instead of chemical oxygen demand to initiate the BMP assays and to normalize the results. The coefficient of variation for the assays performed in triplicate ranged from1.6% to 33% in which the majority was less than 15%. For five of the substrate types analyzed (beef manure, dairy manure, cheese when lactate permeate, food processing marinate, and enzyme process by-product), multiple samples were assayed from different sources. The sample standard deviations indicated that methane production potential could be affected by material source and that BMP assays reported here should only be used as an estimate when considering which types of materials to assay. © 2011 American Society of Agricultural and Biological Engineers. Source


Rahman S.,North Dakota State University | Xin H.,Iowa State University | Xin H.,Egg Industry Center | Roberts S.A.,Akey Nutrition and Research Center | And 6 more authors.
Transactions of the ASABE | Year: 2012

Ammonia (NH3) emissions from laying hens are affected by nutrient content of the diet, manure quantity, and manure properties such as moisture content, nitrogen content, and pH. These production traits may vary with strain of the hen. However, limited information is available concerning the effects of laying-hen genetics on manure properties and NH3 emission. This study was conducted to comparatively quantify production performance, manure properties, and NH3 emissions (through N mass balance) of four white-egg-laying strains (Hy-Line W-36, Hy-Line W-98, Lohmann LSL Lite, and Bovans White) and four brown-egg-laying strains (Hy-Line Brown, Lohmann Brown, ISA Brown, and Bovans Brown) during two production periods of 27-28 weeks (P1) and 35-36 weeks (P2) of age. The diets were formulated to meet the nutritional needs of the brown and white hens. As a result, crude protein contents during P1 and P2 were, respectively, 13.2% and 15.2% for the brown hens but 14.5% and 17.4% for the white hens. The results showed that the brown and white hens had similar hen-day egg production (97.5% to 89.2% for brown hens and 96.0% to 88.2% for white hens) and egg mass output (57.1 to 52.6 g d-1 hen-1 for brown hens and 55.6 to 51.2 g d-1 hen-1 for white hens) but different feed consumption (112 to 98 g d-1 hen-1 for brown hens and 101 to 93 g d-1 hen-1 for white hens, p < 0.01) and feed efficiency (1.97 to 1.87 g feed g-1 egg for brown hens and 1.82 g feed g-1 egg for white hens, p < 0.0001 and p = 0.11). The higher feed consumption for the brown hens stemmed from their heavier body mass (1.81 to 1.78 kg vs. 1.56 to 1.53 kg for white hens). Manure moisture content was higher for the brown hens than for the white hens, although the dry-matter manure production was not significantly different. The results further revealed that under the experimental conditions (i.e., higher CP contents of the diet for the white hens than for the brown hens) the white hens had higher NH3 emissions than the brown hens as expressed per hen (37% to 19% higher, p = <0.001 to 0.016), per animal unit (AU, 500 kg live body mass; 59% to 39% higher, p = 0.0007 to 0.007), per unit of egg mass output (41% to 24% higher, p = 0.01 to 0.09), per unit of feed N consumed (39% to 27% higher, p = 0.01 to <0.0001), and per unit of dry manure (56% to 39% higher, p = 0.001 to 0.007). Certain differences existed in production performance among strains within the brown or white hens, but no differences in NH3 emissions were detected. Because of the relatively small sample size (number of hens involved) and the relatively short monitoring period, the results should be referenced with these limitations in mind. Further larger-scale studies with longer monitoring periods to verify these findings are warranted. © 2012 American Society of Agricultural and Biological Engineers. Source


Moody L.B.,Fertilizer Institute | Burns R.T.,University of Tennessee at Knoxville | Sell S.T.,Iowa State University | Bishop G.,Iowa State University
Applied Engineering in Agriculture | Year: 2011

While there has been increasing interest in manure anaerobic digesters during the past decade, economic constraints remain a limitation to widespread use of the technology. Literature has suggested that co-digestion with other available organic co-substrates could increase the economic viability of manure anaerobic digesters by increasing methane production potential. However, co-substrates must be carefully selected to avoid adding complexities to the manure digestion process. Biochemical methane potential (BMP) assays have been reported to provide a good initial evaluation of potential co-substrates, but they are performed under conditions optimized for the microbes, and the co-substrate is assayed under diluted conditions. Anaerobic toxicity assays (ATAs) provide additional information that could be utilized with BMP results to assist with co-substrate selection. An ATA evaluates a substrate's ability to inhibit methane production and thus determine its potential toxicity. This article provides specific details about the ATA process used by the Agricultural Waste Management Laboratory at Iowa State University on potential digester materials, including the assay method and utilization of the results. The two potential digester materials presented in this article provide examples of a toxic and a non-toxic material. Specifically, normalized BMP results indicated that the industry process by-product produced 60 mL CH 4/g VS, and that it was not toxic at material inclusion rates of up to 49%. Conversely, the enzyme process by-product produced normalized BMP results yielding 284 mL CH 4/g VS, but based on ATA results was highly toxic at all inclusion rates. These results clearly indicate the need to thoroughly evaluate co-digestion co-substrates. © 2011 American Society of Agricultural and Biological Engineers. Source


Andersen D.S.,Iowa State University | Burns R.T.,University of Tennessee at Knoxville | Moody L.B.,Fertilizer Institute | Helmers M.J.,Iowa State University
Applied Engineering in Agriculture | Year: 2011

Increased environmental awareness has promoted the need for improved feedlot runoff control. The use of vegetative treatment systems (VTSs) to control and treat feedlot runoff may enhance environmental security and protect water quality. Knowledge of effluent nutrient concentrations throughout the vegetative treatment system is required to evaluate system performance and impact on water quality. Previously collected VTS monitoring data has provided the opportunity to investigate relationships between effluent quality parameters. The objective of this study was to evaluate, through correlation and regression, the relationships between total solids, nutrients, and effluent quality indicator concentrations of feedlot runoff at various stages of treatment in a VTS, including solid settling basin, vegetative infiltration basin, and vegetative treatment area effluent. Results of a correlation and primary factor analysis showed that most of the effluent concentrations were strongly correlated to each other, with a single factor capable of describing more than 60% of the total variability of the monitored parameters. Regression equations were developed to relate nutrient content and effluent quality indicator concentrations to total solids concentrations. Results were satisfactory for NH 3-N, BOD 5, COD, Cl -, TP, and TKN, indicating that total solids concentrations provided significant insight into VTS performance relative to nutrient concentration and effluent quality indicators. A comparison between predicted, based on total solids content, and monitored annual mass release of the parameters was conducted. No statistical difference was found for NH 3-N, BOD 5, COD, Cl -, TP, and TKN; indicating that effluent volume release along with total solids concentrations could be used to provide an estimate of nutrient mass in solid settling basin, vegetative infiltration basin, and vegetative treatment area effluent. © 2011 American Society of Agricultural and Biological Engineers. Source


Andersen D.S.,Iowa State University | Burns R.T.,Iowa State University | Burns R.T.,University of Tennessee at Knoxville | Moody L.B.,Iowa State University | And 6 more authors.
Journal of Environmental Management | Year: 2013

Beef feedlots of all sizes are looking for more cost-effective solutions for managing feedlot runoff. Vegetative treatment systems are one potential option, but require performance evaluation for use on concentrated animal feeding operations. The performance of six vegetative treatment systems on open beef feedlots throughout Iowa was monitored from 2006 through 2009. These feedlots had interim, National Pollution Discharge Elimination System permits that allowed the use of vegetative treatment systems to control and treat runoff from the open feedlots. This manuscript focuses on making within site comparisons, i.e., from year-to-year and component-to-component within a site, to evaluate how management changes and system modifications altered performance. The effectiveness, in terms of effluent concentration reductions, of each system was evaluated; nutrient concentration reductions typically ranged from 60 to 99% during treatment in the vegetative components of the vegetative treatment systems. Monitoring results showed a consistent improvement in system performance during the four years of study. Much of this improvement can be attributed to improved management techniques and system modifications that addressed key performance issues. Specifically, active control of the solid settling basin outlet improved solids retention and allowed the producers to match effluent application rates to the infiltration rate of the vegetative treatment area, reducing the occurrence of effluent release. Additional improvements resulted from system maturation, increased operator experience, and the addition of earthen flow spreaders within the vegetative treatment area to slow flow and provide increased effluent storage within the treatment area, and switching to active management of settling basin effluent release. © 2013 Elsevier Ltd. Source

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