Optimum moisture levels for biodegradation of mortality composting envelope materials

Ahn, Heekwon; Richard, Tom L.; Glanville, Thomas D.

doi:10.1016/j.wasman.2007.05.022

Cited by 75 publications

(48 citation statements)

References 21 publications

(25 reference statements)

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“…For very moist and dense envelope materials like corn silage, duct spacing of 0.5 m or less is likely to be needed to insure achievement of the recommended minimum matrix O2 concentration of 5%. Relatively low O2 concentrations observed in silage test units during trials #1 and 2 also are consistent with earlier work by Ahn et al, (2008aAhn et al, ( , 2008b showing the gas permeability of silage to be <40% of that for moist ground cornstalks (<19% if dry), and < 35% of that for moist oat straw (<26% if dry).…”

Section: Oxygen Concentrationssupporting

confidence: 90%

“…The relationship between initial envelope material m.c. and T30 is consistent with work by Ahn et al (2008a) that documented increased rates of envelope material biodegradation and heat production as m.c. increased.…”

Section: Internal Temperature (Field Trials)supporting

confidence: 88%

“…Failure to vent excess water vapor from the pile can cause saturation and further weakening of the matrix. Ahn et al (2008aAhn et al ( , 2008b reported that at 80% of their water-holding capacity, the mechanical strength and gas permeability of ground cornstalks were only 22% and 46%, respectively, of the strength and permeability of cornstalks at 20% of their water-holding capacity.…”

Section: Introductionmentioning

confidence: 99%

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Performance of a plastic-wrapped composting system for biosecure emergency disposal of disease-related swine mortalities

et al. 2016

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A passively-ventilated plastic-wrapped composting system initially developed for biosecure disposal of poultry mortalities caused by avian influenza was adapted and tested to assess its potential as an emergency disposal option for disease-related swine mortalities. Fresh air was supplied through perforated plastic tubing routed through the base of the compost pile. The combined air inlet and top vent area is ⩽∼1% of the gas exchange surface of a conventional uncovered windrow. Parameters evaluated included: (1) spatial and temporal variations in matrix moisture content (m.c.), leachate production, and matrix O2 concentrations; (2) extent of soft tissue decomposition; and (3) internal temperature and the success rate in achieving USEPA time/ temperature (T) criteria for pathogen reduction. Six envelope materials (wood shavings, corn silage, ground cornstalks, ground oat straw, ground soybean straw, or ground alfalfa hay) and two initial m.c. 's (15-30% w.b. for materials stored indoors, and 45-65% w.b. to simulate materials exposed to precipitation) were tested to determine their effect on performance parameters (1-3). Results of triple-replicated field trials showed that the composting system did not accumulate moisture despite the 150 kg carcass water load (65% of 225 kg total carcass mass) released during decomposition. Mean compost m.c. in the carcass layer declined by ∼7 percentage points during 8-week trials, and a leachate accumulation was rare. Matrix O2 concentrations for all materials other than silage were ⩾10% using the equivalent of 2 m inlet/vent spacing. In silage O2 dropped below 5% in some cases even when 0.5 m inlet/vent spacing was used. Eight week soft tissue decomposition ranged from 87% in cornstalks to 72% in silage. Success rates for achievement of USEPA Class B time/ temperature criteria ranged from 91% for silage to 33-57% for other materials. Companion laboratory biodegradation studies suggest that Class B success rates can be improved by slightly increasing envelope material m.c. Moistening initially dry (15% m.c.) envelope materials to 35% m.c. nearly doubled their heat production potential, boosting it to levels ⩾silage. The 'contradictory' silage test results showing high temperatures paired with slow soft tissue degradation are likely due to this material's high density, low gas permeability and low water vapor loss. While slow decomposition typically suggests low microbial activity and heat production, it does not rule out high internal temperatures if the heat produced is conserved. Occasional short-term odor releases during the first 2 weeks of composting were associated with top-tobottom gas flow which is contrary to the typical bottom-to-top flow typically observed in conventional compost piles. In cases where biosecurity concerns are paramount, results of this study show the plasticwrapped passively-ventilated composting method to have good potential for above-ground swine mortality disposal. m.c. doubles their heat production potential resulting in significantly hig...

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Section: Oxygen Concentrationssupporting

confidence: 90%

Section: Internal Temperature (Field Trials)supporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Performance of a plastic-wrapped composting system for biosecure emergency disposal of disease-related swine mortalities

et al. 2016

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“…Since the optimum moisture content of compost material is observed near the WHC, thermal property values at 80% of WHC may be used as a standard of practical thermal properties (Ahn et al, 2008b). Thermal conductivity and volumetric heat capacity of saw dust, soil compost blend, beef manure, and turkey litter showed the highest values at 80% of WHC; K (0.12-0.81 W/m°C) and C (1.36-4.08 MJ/m 3°C ).…”

Section: Resultsmentioning

confidence: 99%

Determination of thermal properties of composting bulking materials

Ahn

Sauer²,

Richard

et al. 2009

Bioresource Technology

Self Cite

102

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Thermal properties of compost bulking materials affect temperature and biodegradation during the composting process. Well determined thermal properties of compost feedstocks will therefore contribute to practical thermodynamic approaches. Thermal conductivity, thermal diffusivity, and volumetric heat capacity of 12 compost bulking materials were determined in this study. Thermal properties were determined at varying bulk densities (1, 1.3, 1.7, 2.5, and 5 times uncompacted bulk density), particle sizes (ground and bulk), and water contents (0, 20, 50, 80% of water holding capacity and saturated condition). For the water content at 80% of water holding capacity, saw dust, soil compost blend, beef manure, and turkey litter showed the highest thermal conductivity (K) and volumetric heat capacity (C) (K: 0.12-0.81 W/m °C and C: 1.36-4.08 MJ/m 3°C ). Silage showed medium values at the same water content (K: 0.09-0.47 W/m °C andC: 0.93-3.09 MJ/m 3°C ). Wheat straw, oat straw, soybean straw, cornstalks, alfalfa hay, and wood shavings produced the lowest K and C values (K: 0.03-0.30 W/m °C and C: 0.26-3.45 MJ/m 3°C ). Thermal conductivity and volumetric heat capacity showed a linear relationship with moisture content and bulk density, while thermal diffusivity showed a nonlinear relationship. Since the water, air, and solid materials have their own specific thermal property values, thermal properties of compost bulking materials vary with the rate of those three components by changing water content, bulk density, and particle size. The degree of saturation was used to represent the interaction between volumes of water, air, and solids under the various combinations of moisture content, bulk density, and particle size. The first order regression models developed in this paper represent the relationship between degree of saturation and volumetric heat capacity (r = 0.95-0.99) and thermal conductivity (r = 0.84-0.99) well. Improved knowledge of the thermal properties of compost bulking materials can contribute to improved thermodynamic modeling and heat management of composting processes. KeywordsThermal properties, Compost bulking materials, Thermal conductivity, Thermal diffusivity, Volumetric heat capacity RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. b s t r a c tThermal properties of compost bulking materials affect temperature and biodegradation during the composting process. Well determined thermal properties of compost feedstocks will therefore contribute to practical thermodynamic approaches. Thermal conductivity, thermal diffusivity, and volumetric heat capacity of 12 compost bulking materials were determined in this study. Thermal properties were determined at varying bulk densities (1, 1.3, 1.7, 2.5, and 5 times uncompacted bulk density), particle sizes (ground and bulk), and water contents (0, 20, 50, 80% of water holding capacity and saturated condition). For the water con...

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“…Silage's higher biodegradability-due in part to its favorable initial moisture content for microbial activity (74% vs 29% for cornstalks) (Table 4) and to partial decomposition during the ensiling process-is believed to be the main reason for this. Higher biodegradability for silage was evidenced by internal temperatures in silage field test units that, regardless of ambient temperatures, were consistently 10-30°C higher than in cornstalks (Glanville et al 2005), and also by laboratory biodegradability tests (Ahn et al 2008b) showing maximum oxygen uptake rates of 50 and 12 mg O 2 /g VS respectively for silage and cornstalks.…”

Section: Leachate Qualitymentioning

confidence: 94%

Soil Contamination Caused by Emergency Bio-Reduction of Catastrophic Livestock Mortalities

Glanville

Ahn

Richard

et al. 2008

Water Air Soil Pollut

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Catastrophic regional losses of poultry and livestock have caused environmental officials in North America to seek emergency on-farm disposal alternatives that pose less pollution risk to soil and shallow groundwater than burial. Bio-decomposition of remains followed by land application of the resulting product is used throughout the U.S. and Canada for management of routine poultry, swine, and cattle mortalities, and is often cited as being more environmentally friendly than burial since it recycles nutrients and other potential pollutants into the topsoil and crop production cycle, rather than placing them deeper in the ground and closer to groundwater. During emergencies, however, when time and resources are limited, bioreduction is likely to be done in unsheltered windrows constructed on unprotected soil-conditions that could cause localized soil pollution. Pollution associated with emergency bio-reduction procedures was assessed by Water Air Soil Pollut (2009) 198:285-295 DOI 10.1007 Note: Due to the heterogeneous inputs and layered structure of onfarm emergency mortality disposal "composting" operations, the authors have chosen to refer to this as "bio-reduction" rather than composting which has long been associated with frequently-and completely-mixed solid waste treatment processes designed to achieve homogeneous matrix characteristics that are considered optimal for high rates of biological activity. comparing pre-and post-bio-reduction concentrations in soil beneath the bio-reduction sites. Small but statistically significant (p<0.05) increases in chloride at depths of 1.2 m indicated that bio-reduction leachate reached this depth. Significant increases in % total nitrogen and % total carbon were observed only in the top 15 cm of soil, but large increases in total ammonia-nitrogen were observed at depths of 30-90 cm. The total mass of N added to soil by bio-reduction was 10-25% of the estimated total N in the cattle carcasses, indicating that bio-reduction poses a lower pollution threat to soil and shallow groundwater than burial. T. D. Glanville (*)Department

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Optimum moisture levels for biodegradation of mortality composting envelope materials

Cited by 75 publications

References 21 publications

Performance of a plastic-wrapped composting system for biosecure emergency disposal of disease-related swine mortalities

Performance of a plastic-wrapped composting system for biosecure emergency disposal of disease-related swine mortalities

Determination of thermal properties of composting bulking materials

Soil Contamination Caused by Emergency Bio-Reduction of Catastrophic Livestock Mortalities

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