Aeration to Improve Biogas Production by Recalcitrant Feedstock

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Purpose

Why aerate biogas digesters?

Most agricultural waste is largely composed of polymers such as lignin and complex carbohydrates that are slowly or nearly completely non-degradable in anaerobic environments. An example of such a waste is chicken litter in which wood chips, rice hulls, straw and sawdust are commonly employed bedding materials.  This makes chicken litter a poor candidate for anaerobic digestion because of inherently poor digestibility and, as a consequence, low gas production rates.

Previous studies, however, have shown that the addition of small amounts of air to anaerobic digestates can improve degradation rates and gas production. These studies were largely performed at laboratory-scale with no provision to keep the added air within the anaerobic sludge.

What Did We Do?

Picture of 4 digesters with sprayer tanksFour digesters were constructed out of 55 gallon sprayer tanks. The digestate was 132 L in volume with a dynamic headspace of 76 L. At the bottom of each tank a manifold was constructed from ½” PVC pipe in an “H” configuration and with a volume of approximately 230 mL. The bottom of the manifold had holes drilled in it to allow exchange with the sludge. Tanks were fed 400 g of used top dressing chicken litter (wood shaving bedding) obtained from a local producer (averaging 40% moisture and 15% ash) in 2 L of water through a port in the tank [labeled “1” in figure]. Two hundred mL of air were fed to the manifold through a flow meter [2] 0, 1, 4, or 10 times daily in 15-minute periods at widely spaced intervals by means of an air pump and rotary timer [4]. A gas port [3] at the top of the tank allowed for sampling and led to a wet tip flow meter (wettipflowmeters.com) to measure gas production. Digestate samples were taken out of a side port [5] for measurement of water quality and dissolved gases and overflow was discharged from the tank by means of a float switch wired in line with a ½” PVC electrically actuated ball valve.

Seven dried and weighed tulip poplar disks were added to each tank at the beginning of the experiment. At the end of the experiment, the disks were cleaned and dried for three days at 105 0C before re-weighing. Dissolved and headspace gases were measured on a gas chromatograph equipped with FID, ECD, and TCD detectors. Water quality was measured by standard APHA methods.

What Have We Learned?

Graph of chemical oxygen demand per liter and graph of liters of biogas per day

Adding 800 mL of air daily increased biogas production by an average of 73.4% compared to strictly anaerobic digestate. While adding 200 mL of air daily slightly increased gas production, adding 2 L per day decreased gas production by 16.7%.

Aerating the sludge improved chemical oxygen demand (COD) with the greatest benefit occurring at 2,000 mL added air per day. As noted, however, this decreased gas production in the control indicating toxicity to the anaerobic sludge.

The experiment was stopped after 148 days. When the tanks were opened, there was widespread fungal growth both on the surface of the digestate and the wood disks in the aerated tanks [left], whereas non-aerated tanks showed little evidence of fungal growth [right]. While wood disks subjected to all treatments lost significant mass (t-test, α=0.05), disks in the anaerobic tank lost the least amount of weight on average (6.3 g) while all other treatments lost over 7 g weight on average.

Picture of widespread fungal growth on the surface of the digestate and the wood discs in aerated tanks

Future Plans

Research on other feedstocks and aeration regimes are being conducted as are 16s and 18s community analyses.

Chart of grams dry weight pre experiment and post experiment

Corresponding author (name, title, affiliation)

John Loughrin, Research Chemist, Food Animal Environmental Research Systems, USDA-ARS, 2413 Nashville Rd. B5, Bowling Green, KY 42104

Corresponding author email address

John.loughrin@ars.usda.gov.

Other Authors

Karamat Sistani, Supervisory Soil Scientist, Food Animal Environmental Research Systems. Nanh Lovanh, Environmental Engineer, Food Animal Environmental Research Systems.

Additional Information

https://www.ars.usda.gov/midwest-area/bowling-green-ky/food-animal-envir…

Acknowledgements

We thank Stacy Antle and Mike Bryant (FAESRU) and Zachary Berry (WKU Dept. of Chemistry) for technical assistance.

Composting of Dairy Manure with the Addition of Zeolites to Reduce Ammonia Emissions

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Purpose

The purpose of this project was to demonstrate the effects of adding natural clinoptilolite zeolites to a dairy manure compost mix at the moment of initiating the composting process on ammonia emissions, nitrogen retention, composting performance, and characteristics of the final compost product. A typical dairy cow in the U.S. produces approximately 148 lb of manure daily (feces and urine, not counting bedding; Lorimor et al., 2000). This amounts to millions of tons of monthly manure production. On-farm composting of manure is one of the most-used practices to manage dairy manure in Idaho. Composting reduces manure volume between 35 and 50%, which allows the material to be significantly more affordable to transport than fresh, wet manure. Composting converts the nitrogen (N) present in the raw manure into a more stable form, which is released slowly over a period of years and thereby not totally lost to the environment. Composting contributes to alleviating problems associated with ground and surface water contamination and also reduces odor complaints (Rink et al., 1992; Fabian et al., 1993). During the manure handling and composting process, between 50 and 70% of the nitrogen can be lost as ammonia if additional techniques are not used to increase nitrogen retention. In most cases, manures from dairies and other livestock operations don’t have the proper carbon to nitrogen (C:N) ratio to be composted efficiently without added carbon (usual straw bedding has a C:N of 60 to 90). Dairy cow manure is rich in nitrogen (C:N ratios below 18:1), causing a great proportion of the available nitrogen to be lost as ammonia due to the lack of carbon to balance the composting process. The loss of nitrogen from manures as ammonia reduces the nutrient value of the manure, produces an inefficient composting process, and generates local and regional pollution. Lack of carbon also results in a lower-grade compost that can carry elevated concentrations of salts, potassium and phosphorous. In many arid zones there are not enough sources of carbon to balance the nitrogen present in the manure.

Zeolite is a mineral defined as a crystalline, hydrated aluminosilicate of alkali and alkaline earth cations having an infinite, open, three-dimensional structure. Zeolites are able to further lose or gain water reversibly and to exchange cations with and without crystal structure (Mumpton, 1999). Zeolites are mined in several western U.S. states where dairy production also is concentrated. This paper showcases a project that explored the effects of adding natural zeolites to dairy manure at the time of composting as a tool to reduce ammonia emissions and retain nitrogen in the final composted product.

What did we do?

This on-farm research and demonstration study was conducted at an open-lot dairy in southern Idaho with 100 milking Jersey cows. Manure stockpiled during the winter and piled after the corral’s cleaning was mixed with freshly collected manure from daily operations and straw from bedding and old straw bales, in similar proportions for each windrow. The compost mixture was calculated using a compost spreadsheet calculator (WSU-Puyallup Compost Mixture Calculator, version 1.1.; Puyallup, WA). Moisture was adjusted by adding well water to reach approximately 50% to 60% moisture on the initial mix. Windrows were mixed and mechanically turned using a tractor bucket. Three replications were made on control and treatment. The control consisted of the manure and straw mix as described. The treatment consisted of the same mix as the control, plus the addition of 8% of clinoptilolite zeolite by weight during the initial mix. Windrows were actively composted for four months or more. Ammonia emissions were measured using passive samplers (Ogawa & Co., Kobe, Japan) for the first five to seven days after building each windrow (called turn 1 in Figure 1) and after the two subsequent turns. Ammonia emissions per measurement period and per turn were obtained. Three periods of one to three days at the time of building each windrow and after the first turn were measured. After the second turn, two measurement periods of three to four days were made. Values of mg NH3-N/m3 are time-corrected by minutes of sampling (Figure 1). Complete initial manure (compost feedstock mix) and final screened compost nutrient lab analyses were performed for each windrow. Analyses of variance (ANOVA) on lab data and on ammonia samples were performed using SAS 9.4 (SAS Institute, Cary, NC).

Figure 1. Ammonia emissions per period and turn

What have we learned?

The addition of 8% w/w natural zeolites to the dairy manure compost mix on a mechanically turned system using a tractor bucket reduced cumulative ammonia emissions by 11% during the first three turns (Figure 2) and showed a significant reduction trend in ammonia emissions. Figure 1 shows the differences and trend line in ammonia emissions per monitoring period and per turn. Treated windrows’ cumulative emissions were significantly lower (P<0.05) at 2.76 mg NH3-N/m3 from control windrows at 3.09 mg NH3-N/m3. Nitrates (NO3) on the composted treatment (702 ppm) were 3 times greater (p=0.05) than the control (223 ppm) (Figure 3). These results demonstrate that the addition of natural zeolites has a positive effect on reducing ammonia emissions during the composting process and increasing the conversion to nitrates, retaining nitrogen in the compost in a form that is more available to crops.

Figure 2. Cumulative ammonia emissions

Figure 3. Nitrate, ppm before and after composting

Future Plans

Field days and journal publications about this project are expected to occur within the next year.

Corresponding author, title, and affiliation

M. E. de Haro-Martí. Extension Educator. University of Idaho Extension, Gooding County, Gooding, Idaho.

Corresponding author email

mdeharo@uidaho.edu

Other authors

M. Chahine. Extension Dairy Specialist. University of Idaho Extension, Twin Falls R&E Center, Twin Falls, Idaho. H. Neibling. Extension Irrigation Engineer. University of Idaho Extension, Kimberly R&E Center, Kimberly, Idaho. L. Chen. Extension Waste Management Specialist,

Additional information

References:

Fabian, E. F., T. L. Richard, D. Kay, D. Allee, and J. Regenstein. 1993. Agricultural composting: a feasibility study for New York farms. Available at: http://compost.css.cornell.edu/feas.study.html . Accessed 04/28/2011.

Lorimor, J., W. Powers, A. Sutton. 2000. Manure Characteristics. Manure Management System Series. Midwest Plan Service. MPWS-18 Section 1. Iowa State University.

Mumpton, F.A. 1999. La roca magica: Uses of Natural Zeolites in Agriculture and Industry. Proceedings of the National Academy of Sciences of the United States of America, Vol. 96, No. 7 (Mar. 30, 1999), pp. 3463-3470

Rink, R., M. van de Kamp, G.B. Willson, M.E. Singley, T.L. Richard, J.J. Kolega, F.R. Gouin, L.L. Laliberty Jr., D.K. Dennis. W.M. Harry, A.J. Hoitink, W.F.Brinton. 1992. On-Farm Composting Handbook. NRAES-54. Natural Resource, Agriculture, and Engineering Service. Cooperative Extension. Ithaca, New York.

Acknowledgements

This project was made possible through a USDA- ID NRCS Conservation Innovation Grants (CIG) # 68-0211-11-047. The authors also want to thank the involved dairy farmer and colleagues that helped during this Extension and research project. Thanks to Dr. April Leytem and her technicians at USDA-ARS in Kimberly, ID, for the loan of the Ogawa passive samplers and for sample analysis.

Additive to Mitigate Odor and Hydrogen Sulfide Gas Risk from Gypsum Bedded Dairy Manure

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Purpose

Dangerous levels of hydrogen sulfide (H2S) gas released from gypsum-bedding-laden dairy manure storages have imposed risks to animal and human health, as demonstrated both on-farm and in bench scale studies (Fabian-Wheeler et al., 2017; Hile, 2016). Gypsum bedding is popular with some producers for advantages to cow comfort and health along with agronomic benefits. This project demonstrated the effect of iron oxide (FeO2) as a promising additive to dairy manure storages on mitigating H2S releases and odor.

What did we do?

Two bench-scale trials comprised three replicates each (15 kg manure each vessel) of three treatments: (1) control (dairy manure only), (2) manure with gypsum added 0.35% by weight, and (3) manure with gypsum and iron oxide added at a 1:1 molar ratio with gypsum. Headspace gas concentrations were measured using a Fourier transform infrared analyzer (FTIR model 700, California Analytical, Inc., Orange, CA) from each experimental vessel prior to and during manure agitation. Nutrient analyses were performed upon initial mixing and at the end of the incubations (PSU Agricultural Analytical Laboratory and Fairway Laboratories). Final incubation of the first trial included an odor evaluation of headspace gas according to international standard EN 13725 using qualified human assessors at the Penn State Odor Assessment Laboratory (abe.psu.edu/research/natural-resource-protection/odors). Odor quality testing on undiluted headspace gas used the labelled magnitude scale (LMS), Odor Intensity Referencing Scale (OIRS) and Hedonic Tone (pleasantness).

What have we learned?

High total sulfur in gypsum-laden manure confirms that gypsum provides the sulfur source that is converted to H2S. However, introduction of iron oxide maintained 98.8% total sulfur of manure sample by the end of incubation. The H2S concentrations remain low (below 5 ppm) in static conditions until gases are immediately released as soon as manure is agitated. Maximum H2S concentrations were reduced 83% to 96% in gypsum-laden manure by adding iron oxide (Figure 1). Despite anecdotal field reports of increased malodor associated with gypsum bedded manure, odor detection threshold (DT) did not increase with addition of gypsum compared to the control (manure only). However a 1:1 molar ration of iron oxide reduced the DT by approximately 50%. Odor quality results show that gypsum-laden manure created a less pleasant odor when compared to control manure.

Figure 1. Analyzer H2S concentrations from vessel headspace for each treatment evaluated sequentially over time during three agitation events at day 17, 24, and 31 manure age

Future Plans

Field-scale research would strengthen these findings and document management and economics associated with the iron oxide treatment use on farm. Additional odor surveys would confirm odor intensity reduction via iron oxide.

Corresponding author, title, and affiliation

Eileen E. Fabian (Wheeler), Professor in Agricultural and Biological Engineering (ABE) at Penn State (PSU)

Corresponding author email

fabian@psu.edu

Other authors

Long Chen, Ph.D. Candidate in ABE at PSU, Dr. Michael Hile, Project Associate in ABE at PSU and Dr. Mary Ann Bruns, Associate Professor in Ecosystems Science & Management at PSU

Additional information

Fabian-Wheeler, E., M. L. Hile, D. J. Murphy, D. E. Hill, R. Meinen, R. C. Brandt, H. A. Elliott, D. Hofstetter. 2017. Operator Exposure to Hydrogen Sulfide from Dairy Manure Storages Containing Gypsum Bedding. Journal Agricultural Safety and Health 23(1): 9-22.

Hile. M. L. 2016. Hydrogen sulfide production in manure storages on Pennsylvania dairy farms using gypsum bedding. Ph.D. dissertation. University Park, PA.: The Pennsylvania State University, Department of Agricultural and Biological Engineering.

Acknowledgements

This work was a partnership of Penn State College of Agricultural Sciences graduate student competitive grant program, Penn State Extension, and USA Gypsum

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.

Recommendations of the Chesapeake Bay Program Expert Panel on Manure Treatment Technologies

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Purpose

The US EPA Chesapeake Bay Program assesses nutrient loading to the Chesapeake Bay. There is a need to determine the impact of manure treatment technologies on reducing the nitrogen and phosphorus loading from agriculture. Furthermore, many states within the Chesapeake Bay Watershed control nutrient discharges through watershed nutrient trading programs. Tables of standard nutrient removal efficiencies of various technologies will allow states to implement these programs.

What did we do?

The panel standing on the dock of the Chesapeake Bay

An expert panel was convened by the EPA Chesapeake Bay Program to determine nutrient removal potential of manure treatment technologies. The following seven technology categories were reviewed: thermochemical processing, anaerobic digestion, composting, settling, mechanical solid-liquid separation, and wet chemical treatment. Within these categories, the panel defined 24 named technologies for detailed review. The scientific literature was reviewed to determine the ability of each technology to transfer volatile nitrogen to the atmosphere and transfer nutrients to a waste stream more likely to be used off-farm (or transported out of the Chesapeake Bay Watershed).

What have we learned?

Manure treatment technologies are used reduce to odors, solids, and organic matter from the manure stream, with only minor reductions in nutrient loading. The panel determined that Thermo-Chemical Processing and Composting have the potential to volatilize nitrogen, and all of the technologies have the ability to transfer nutrients into a more useful waste stream. The greatest effect of treatment technologies is the transformation of nutrients to more stable forms – such as precipitation of insoluble phosphorus from dissolved phosphorus.

Future Plans

The panel’s report is undergoing final authorization from the Chesapeake Bay Program for release to the public. Future panels may choose to revisit the issue of nutrient reduction from manure treatment technologies. The current panel recommends future panels expand the categories of technologies to include liquid aerobic treatment, and examine more named technologies as they become available within the Chesapeake Bay Watershed.

Corresponding author, title, and affiliation

Douglas W. Hamilton, Associate Professor Oklahoma State University

Corresponding author email

dhamilt@okstate.edu

Other authors

Keri Cantrell, KBC Consulting;John Chastain, Clemson University; Andrea Ludwig, University of Tennessee; Robert Meinen, Penn State University; Jactone Ogejo, Virginia Tech; Jeff Porter, USDA Natural Resource Conservation Service, Eastern Technology Suppor

Additional information

https://www.chesapeakebay.net/

http://osuwastemanage.bae.okstate.edu/

Two related presentations given at the same session at Waste to Worth 2017

Acknowledgements

Funding for this panel was provided by the US EPA Chesapeake Bay Program and Virginia Tech University through EPA Grant No. CB96326201

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.

Evaluating the Impact of Ammonia Emissions from Equine Operations on the Environment


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Purpose 

In the United States, animal agriculture is the largest source of ammonia (NH3) emissions that are a major air and water pollutant contributing to eutrophication, soil acidity, and aerosol formation that can impair atmospheric visibility and human health. Ammonia volatilization occurs when excess crude protein (CP) is fed and excreted as urinary nitrogen, primarily as urea. Information regarding NH3 emissions from equine operations is limited. It is generally understood that air quality in stables can adversely affect both horse and human health, however, the effects of different housing systems and nutritional management of horses on air quality have received little investigation.

What did we do? 

In the first study, 9 mature horses were used in a 3 X 3 replicated Latin square design study to determine the effects of dietary CP concentrations on potential NH3 losses from feces and urine. Horses were fed 3 diets formulated using bahiagrass and Tifton-85 bermudagrass hays and a commercial vitamin mineral supplement. The 3 diets differed in dietary CP concentration and were labelled as: LOW-CP, MED-CP, and HIGH-CP (10.6, 11.5 and 12%, respectively). Total collection of feces and urine was conducted over 3 days. For in-vitro determination of NH3 concentrations, urine samples were pooled and mixed with either wheat straw or wood shavings, while fecal samples were pooled and mixed with wheat straw. Ammonia emission by these samples was measured using a vessel emission system with an airflow rate (2.5 L min-1) at 20°C over a 7-d period. Concentration of NH3 in each vessel was measured using a photoacoustic multi-gas analyzer. Temperature, airflow rate and NH3 concentration in each vessel were used to calculate NH3 emission rate (ER).

The objective of the second study was to determine air emissions from 4 Mid-Atlantic equine operations as affected by housing type and feeding practices. A questionnaire was administered to respective farm managers to record facility and individual stall dimensions, daily cleaning practices, and feeding practices. Farm A was a University riding stable, Farm B was a University breeding farm, Farm C was a racehorse training facility, and Farm D was a Standardbred breeding facility. At least 4 stalls were chosen in each facility based upon location within barn to quantify NH3 concentrations. Body weight, breed, age, class of horse, exercise schedule, and time spent in the stall were recorded for the horses in the selected stalls. For analysis of NH3 concentration, air samples were collected from stall floors using a dynamic flux chamber and concentrations measured using a photoacoustic NH3 analyzer. To achieve a representation of NH3 emitted from stall surfaces, 5 locations were selected and measurements taken at approximately the same time each day. Temperature, airflow rate and a weighted concentration of NH3 in the flux chamber were used to calculate NH3 emissions.

 

Figure 1 Cumulative ammonia emissions rate of urine when mixed with A) shavings and B) straw and incubated

Figure 2. Daily ammonia emissions per horse over 3 days using the flux chamber system on 4 horse operations

What have we learned? 

When measuring NH3 concentrations and calculating the ER in-vitro, urinary-N was the main source of NH3 volatilized from equine manure, potentially due to the high urea-N concentration in the urine. Cumulative fecal NH3 emissions ranged from 19.7 to 39.8 mg/m2 and contributed only a small amount in comparison to the NH3 lost from urine. While dietary CP intake did not influence NH3 emissions, cumulative emissions tended to be higher when horses consumed more CP. Urinary NH3 emissions were greater when mixed with wheat straw compared to wood shavings. This study shows there may be a relationship between dietary CP intake and potential NH3 losses from equine urine under laboratory conditions. When estimating NH3 emissions on the 4 equine operations, greater dietary CP intake was associated with increased urinary NH3 volatilization. Daily CP intake ranged from 149-211 % above NRC CP requirement. Estimated NH3 emissions from facilities ranged from 18.5 to 124 g d-1 horse-1 and were similar to emissions previously reported from other large livestock species. Differences in NH3 emissions could be due to several factors including cleaning practices and ventilation rate. These studies provide a better understanding of the impact equine operations are having on atmospheric NH3 levels.

Future Plans    

Future research will aim to quantify NH3 emissions from entire equine operations as well as accounting for diurnal, seasonal and regional fluxes in NH3. In addition, there is interest to determine how protein quality will affect NH3 emissions from horse urine.

Corresponding author, title, and affiliation        

Jessie Weir, University of Florida

Corresponding author email   

jessie23@ufl.edu

Other authors   

Hong Li, Assistant Professor, University of Delaware; Lori K. Warren, Associate Professor, University of Florida; Erica Macon, Graduate Student, Middle Tennessee State University; Carissa Wickens, Extension Equine Specialist, University of Florida

Additional information               

Additional information regarding these projects is available by contacting Jessie Weir (jessie23@ufl.edu), or Carissa Wickens (cwickens@ufl.edu). 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.

Using Wet Scrubber to Reduce Ammonia Emission from Broiler Houses


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Purpose 

Research on mitigating the effects of animal feeding operations (AFOs) on air quality in the US has made great strides in recent years. Development of cost-effective air emission mitigation and assessing the effectiveness of these technologies is urgently needed to improve our environmental performance and to help producers address increasing regulatory pressures. Scrubbers have been shown to be a powerful tool in reducing ammonia (NH3), dust and odor emissions. An affordable two-stage acid scrubber was developed by USDA ARS for treating exhaust air and can easily be installed onto the exhaust fans of existing poultry facilities. A field project was conducted to evaluate the efficiency of the acid scrubber under field conditions on three broiler farms, two located in Delaware (DE) and one located in Pennsylvania (PA).

What did we do? 

The two-stage scrubbers were installed on the minimum fans of three farms that were using different practices and settings. One farm used 36” minimum fans and reused existing litter throughout the project while an organic farm used a 36” minimum fan, but used new bedding materials for every flock. The third scrubber was installed on a research farm with a 24” minimum fan and used litter. Sodium bisulfate was used as the acid agent. Ammonia concentration and airflow rate through each fan were continuously measured. Scrubber liquid samples were analyzed to calculate the efficiency of each scrubber. Acid, water and electricity consumption of each scrubber were recorded over multiple flocks and seasons.

What have we learned?              

The mean NH3 capturing efficiencies of the three scrubbers for the three sites were 31.3, 34.3 and 11.0 %, respectively. The low efficiency (11%) of one scrubber was due to high NH3 emission rate and inadequate acid solution in the scrubber (the solution at this site was checked and replaced weekly whereas the solution at the other two sites were checked daily). For every kg NH3 captured, the average water, sodium bisulfate and electricity consumption at the three sites were 0.23 m3, 15.10 kg and 43.74 kWh, respectively.

Future Plans 

Based on the field experiences of running the three scrubbers, several recommendations are suggested: 1) increase fan run time to compensate for air flow loss due to high pressure drop, 2) add insulation on drain valves, 3) heat fresh water line and add a heater in pump boxes, 4) clean dust scrubber at least twice per flock for houses with used litter, 5) replace acid solution more frequently toward end of the flock for best performance, 6) add a storage tank for spent liquid if the growers do not have crops or pasture to apply to, and 7) add an automatic acid dosing system to reduce labor requirement and improve scrubber performance.

Corresponding author, title, and affiliation        

Hong Li, Assistant Professor, University of Delaware

Corresponding author email    

hli@udel.edu

Other authors   

Chen Zhang, Philip Moore, Michael Buser, Cathleen J. Hapeman, Paul Patterson, Gregory Martin, Jerry Martin

Additional information              

Zhang, Chen, Hong Li , Philip A Moore , Michael Buser, Cathleen J. Hapeman, Paul Patterson, Gregory Martin. 2016. ASABE Annual International Conference. Paper number 2461008; Orkando,Florida, July 17 – July 20.

Acknowledgements       

This study was partially supported by funds from USDA-NRCS Conservation Innovation Grant Program (Award No. NRCS 69-3A75-12-244), University of Delaware, Penn State University, Oklahoma State University, University of Maryland, and USDA-ARS. The cooperation and assistance of the collaborating producer is also acknowledged.

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.

Reducing Greenhouse and Ammonia Emissions from Manure Systems


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Purpose             

Dairy manure systems produce greenhouse gas and ammonia emissions that contribute to climate change. There are many potential practices and management strategies that can reduce these emissions which can conserve nutrients and reduce environmental impacts. This work assesses different processing strategies, additives, and manure storage covers to reduce emissions from dairy manure systems.

What did we do? 

We completed three laboratory/field trials to assess emissions from manure systems. The first trial was to assess the greenhouse gas and ammonia emissions during storage and land application of manure that was processed with solid separation and digestion in combination with solid separation. A second trial assessed emissions and manure characteristics from storage with various commercial additives. The third study assessed ammonia emissions from digested manure storages with various biomass covers including raw wood, steam treated wood, and biochar produced from wood and corn cobs.

What have we learned? 

The results from the study indicate that separation and digestion result in significant reductions in greenhouse gas emissions. However, as expected, ammonia emissions following digestion are increased due to increased nitrogen mineralization. Results also indicate that separation alone had a similar impact to greenhouse gas emissions, but did not further reduce emissions following digestion. Commercially available products that are designed to be added to manure storages had little to no impact on emissions or manure characteristics for the conditions present in this study. Lastly, biochar was capable of reducing ammonia emissions significantly when applied as a cover. Although the biochar was capable of sorbing ammonical nitrogen, the results indicate that the physical barrier on the manure surface was the primary driver for the reduction in ammonia emissions.

Future Plans    

Following the outcomes of this work, information is being added to a dairy manure life cycle assessment to determine larger system wide impacts from changes in management practices or the inclusion of a processing system. In addition, work is being conducted to look at potential benefits that may be gained over a number of impact factors when manure management systems are optimized with other waste management systems from the municipal sector.

Corresponding author, title, and affiliation        

Rebecca Larson, Assistant Professor, University of Wisconsin-Madison

Corresponding author email    

rebecca.larson@wisc.edu

Other authors   

M.A. Holly, Agricutural Engineer at USDA ARS, J.M. Powell, Soil Scientist at USDA ARS, H. Aguirre-Villegas, Assistant Scientist at University of Wisconsin-Madison

Additional information 

Holly, M.A., R.A. Larson, M. Powell, M. Ruark, and H. Aguirre-Villegas. 2017. Evaluating greenhouse gas and ammonia emissions from digested and separated manure through storage and land application. Agriculture, Ecosystems & Environment, 239:410-419. http://www.sciencedirect.com/science/article/pii/S0959652616321953

Holly, M.A. and R.A. Larson. 2017. Effects of Manure Storage Additives on Manure Composition and Greenhouse Gas and Ammonia Emissions. Transactions of the ASABE, Accepted in Print.

Holly, M.A. and R.A. Larson. 2017. Evaluation of Biochar, Activated Biochar, and Steam Treated Wood as Dairy Manure Storage Covers for Ammonia Mitigation. In Review.

Acknowledgements       

This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2013-68002-20525. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

 

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.

Integrating Small Scale Digestion Systems in Developing Regions


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Purpose           

People in developing countries regularly lack access to energy or their energy source is not reliable. Low cost anaerobic digestion systems have the potential to provide methane to be used in a variety of end uses. Unfortunately, many low cost systems are not evaluated and it is unclear if they are living up to the expectations of the end users or those that are promoting or financially supporting their installation.

What did we do? 

We have evaluated multiple small scale anaerobic digestion systems in Uganda and Bolivia to assess their energy production potential, impact of digestate as a fertilizer (using plot studies), pathogen reduction through the digester, and impact to kitchen air quality when biogas stoves replace firewood. Based on feedback we have also designed, tested and implemented a low cost separation system for handling digestate to recycle separated liquids and improve handling of solids. We have also modified an absorption chiller to run on biogas and are in the process of wider spread adoption and evaluation.

What have we learned? 

Throughout this assessment we have learned that many institutional level digestion systems in developing countries are not meeting the biogas demands of the end users. While they like the improved cooking time and reduced air quality impacts in the kitchen, only small households are producing enough gas to realize many of these benefits. Biogas poses a reduction in PM2.5 (fine particulates) within kitchens when compared to firewood stoves. However, when any amount of firewood is used in the kitchens (when there is not enough biogas), much of this benefit is lost. Therefore it is critical to improve the biogas production of these systems.

Maize plot trials show that compared to control plots digestate applied in any form (slurry or separated solids) significantly improves yields. When compared to inorganic fertilizer applications the grain yields are statistically similar but the stover yields increase significantly. End users show a preference for using the separated solids and the reduction in water needed to operate the systems. While these benefits seem appealing, there may be concern for the risks associated with pathogens in the digestate when applied to food crops. While digesters showed a significant reduction in pathogen related to the system retention time, pathogen remained in the effluent and must be handled properly to limit transfer to food and the human health risks after ingestion.

Increasing the end use of biogas beyond cooking to chillers has shown great potential for implementation and has high demand for end users. Systems have been able to provide cooling at multiple locations for extended periods with low biogas demands. Additional materials are needed to provide end users with guidance on troubleshooting and operation.

Future Plans    

Based on the results of these studies we are moving forward with farmer trials of the digestate to assess end user issues and motivations. In addition, we are currently designing a low cost heating system to improve biogas production efficiency in order to meet end user needs or decrease the size of digesters. Finally we are working on an evaluation of chiller biogas needs and providing training on all aspects of the digestion systems.

Corresponding author, title, and affiliation      

Rebecca Larson, Assistant Professor at the University of Wisconsin-Madison

Corresponding author email    

rebecca.larson@wisc.edu

Other authors   

A. McCord, Associate Director at University of Wisconsin-Madison, Vianney Tumwesige, CEO at GreenHeat Uganda, Dorothy Lsoto at W2E Uganda

Additional information              

http://www.greenheatinternational.com/

http://www.waste2energyltd.com/

McCord, A.I., S.A. Stefanos, V. Tumwesige, D. Lsoto, A. Meding, A. Adong, J.J. Schauer, and R.A. Larson. 2017. Biogas and the impacts of fuel choice on institutional kitchen air quality in Kampala, Uganda. Indoor Air. In Review, revisions requested.

McCord, A.I., S.A. Stefanos, V. Tumwesige, D.T. Lsoto, M. Kawala, J. Mutebi, I. Nansubuga, and R.A. Larson. 2017. Anaerobic digestion and public sanitation in Kampala: risks and opportunities. In Review.

Fertilizer Value of Nitrogen Captured using Ammonia Scrubbers

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Purpose

Over half of the nitrogen (N) excreted from broiler chickens is lost to the atmosphere as ammonia (NH3) before the manure is removed from the barns, resulting in air and water pollution and the loss of a valuable fertilizer resource. A two stage exhaust scrubber (ARS Air Scrubber) was developed by scientists with USDA/ARS to trap ammonia and dust emissions from poultry and swine facilities. One objective of this study was to determine the fertilizer efficiency of N, which is mainly present as ammonium (NH4), captured from the exhaust air from poultry houses using acid scrubbers, when applied to forages. The second objective was to determine if any of the scrubber solutions resulted in a decrease in phosphorus (P) runoff or soil test P.

What did we do?

This study was conducted using 24 small plots (1.52 x 6.10 m) located on a Captina silt loam soil at the University of Arkansas Agricultural Experiment Station. There were six treatments in a randomized block design with four replications per treatment. The treatments were: (1) unfertilized control, (2) potassium bisulfate (KHSO4) scrubber solution, (3) alum (Al2(SO4)3.14H2O) scrubber solution, (4) sulfuric acid (H2SO4) scrubber solution, (5) sodium bisulfate (NaHSO4) scrubber solution and (6) ammonium nitrate (NH4NO3) fertilizer dissolved in water. The four scrubber solutions, which were obtained from scrubbers attached to exhaust fans on commercial poultry houses, and the ammonium nitrate solution were all applied at an application rate equivalent to 112 kg N ha-1. Forage yields were measured periodically throughout the growing season. A rainfall simulation study was conducted five months after the solutions were applied to determine potential effects on P runoff.

ARS air scrubber in Arkansas

Applying scrubber solutions

Rainfall simulation

What have we learned?

Forage yields (Mg ha-1) followed the order: potassium bisulfate (7.61), sodium bisulfate (7.46) > ammonium nitrate (6.87), alum (6.72), sulfuric acid (6.45) > unfertilized control (5.12). These data indicate that forage yields with scrubber solutions can be equal to or even greater than that obtained with equivalent amounts of N applied as commercial fertilizer. This is likely due to the presence of other nutrients, such as K in acid salts, like potassium bisulfate. Nitrogen uptake followed similar trends as yields, although there were no significant differences among N sources.

 

Total P loads in runoff were 37, 25, 20, 19, 17, and 14 g P ha-1, for sulfuric acid, potassium bisulfate, sodium bisulfate, unfertilized control, ammonium nitrate, and alum. The alum solution resulted in significantly lower P loads than H2SO4. This was likely due to a decrease in the water extractable P (WEP) in the soil, since alum was also shown to significantly reduce WEP compared to the unfertilized control. None of the treatments affected Mehlich III extractable P.

 

Future Plans

Currently research is underway on using acid-tolerant nitrifying bacteria to generate the acidity needed to capture ammonia in the exhaust air from animal rearing facilities.

 

Corresponding author, title, and affiliation

Philip Moore, Soil Scientist, USDA/ARS

Corresponding author email

philipm@uark.edu

Other authors

Jerry Martin, USDA/ARS, Fayetteville, AR; Hong Li, University of Delaware

Additional information

Philip Moore
Plant Sciences 115
University of Arkansas
Fayetteville, AR 72701

Moore, P.A., Jr., R. Maguire, M. Reiter, J. Ogejo, R. Burns, H. Li, D. Miles and M. Buser. 2013.  Development of an acid scrubber for reducing ammonia emissions from animal rearing facilities.  Proc. Waste to Worth Conference. http://lpelc.org/development-of-an-acid-scrubber-for-reducing-ammonia-emissions-from-animal-rearing-facilities.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.

Developing a Comprehensive Nutrient Management Plan (CNMP)

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Purpose

Livestock producers are presented with a number of challenges and opportunities. Developing a quality Comprehensive Nutrient Management Plan (CNMP) can effectively help landowners address natural resource concerns related to soil erosion, water quality, and air quality from manure management. As livestock operations continue to expand and concentrate in certain parts of the country, utilizing a CNMP becomes even more important. Following the NRCS 9-step planning process is critical in developing a good plan. Effective communication is a key element between all parties involved in the planning process. A CNMP documents the decisions made by the landowner for the farmstead area, crop and pasture area, and nutrient management. Information will cover the elements essential for developing a quality CNMP.

What did we do?

Since the CNMP documents the records of decisions by the landowner, it has to be organized in such a fashion that it is understandable to and usable by the landowner. The CNMP is the landowner’s plan. Therefore, the role of the planner is to help landowners do the things that will most benefit them and the resources in the long run. This will take both time and effort. To provide consistency with other conservation planning efforts within NRCS, CNMPs following the same process outlined in the National Planning Procedures Handbook. There are several items that are essential for a quality CNMP to be developed:

• Have a good understanding of potential resource concerns especially soil erosion, water quality and air quality.

• Make the appropriate number of site visits. Trying to do this from the office will likely lead to a poor quality CNMP that may not be implemented.

• Address resource concerns for the Farmstead and Crop and Pasture areas.

• Ensure that all nutrient sources are addressed.

• Follow the 9 steps of planning.

• Decisions are agreed upon by the landowner. The CNMP reflects the landowner’s record of decisions.

• Follow-up to address any questions or concerns.

• Update as necessary. A CNMP is not a static document.

Field

Land application of animal manure without proper land treatment practices

Muddy field with standing water

Proper animal manure storage required to address water quality issues

Picture of lined water bed

Evaluation of storage area to adequately address surface and subsurface
water quality issues

Picture of tractor and tanker spreader

Land application and nutrient management are critical elements for a
properly prepared CNMP

What have we learned?

The quality of CNMPs varies greatly across the country. Some were becoming so large that landowners were having difficulty finding the activities that needed to be completed. The revised CNMP format and process following the NRCS Conservation Planning approach should improve both the quality and usability of the plans developed. Due to statutes in the Farm Bill, all conservation practices recorded in the record of decision of the CNMP, whether receiving financial assistance or not, must be implemented by the end of the established contract period between the landowner and NRCS. Therefore it is important to only include the practices that are going to be implemented. CNMPs should be periodically updated to account for operational changes such as animal numbers, cropping systems, or land application methods.

Future Plans

The CNMP planning process will be evaluated to determine whether landowner objectives are being met and resource concerns properly addressed. Additional evaluations will look at the consistency of the plans generated across the country and the usability by landowners.

Corresponding author, title, and affiliation

Jeffrey P. Porter, P.E.; National Animal Manure and Nutrient Management Team Leader, USDA-Natural Resources Conservation Service

Corresponding author email

jeffrey.porter@gnb.usda.gov

Additional information

References

USDA-NRCS General Manual – Title 190, Part 405 – Comprehensive Nutrient Management Plans

USDA-NRCS Handbooks – Title 180, Part 600 – National Planning Procedures Handbook

Code of Federal Register (CFR) Title 7, Part 1466 – Environmental Quality Incentives Program (1466.7 EQIP Plan of Operations and 1466.21 Contract Requirements)

Webinar

Comprehensive Nutrient Management Plans and the Planning Process – http://www.conservationwebinars.net/webinars/comprehensive-nutrient-management-plans-and-the-planning-process/?searchterm=cnmp

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2017. Title of presentation. Waste to Worth: Spreading Science and Solutions. Cary, NC. April 18-21, 2017. URL of this page. Accessed on: today’s date.