Tag: manure storage

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Existing Equine Pasture Best Management Survey Findings from NE-1441 States


Purpose

Pasture is a good source of nutrition and 94% of U.S. equine operations allow horses to access pastures [8]. Proper management of equine operations requires the adoption of Best Management Practices (BMPs) to balance nutrient production and prevent erosion. Government agencies are concerned about non-point sources of water pollution and have focused on agriculture, including equine operations, as a major contributor to water quality issues. Many states’ laws have regulated equine farms, requiring farm managers to incorporate BMPs. Best Management Practice utilization on horse farms needs to be quantified before regulations are adopted. The objectives of these various states’ surveys were to quantify and assess the use of the equine industry’s BMPs in pasture management and erosion control and to examine potential environmental impacts. The object of this abstract is to compare and look for some similarities in the ways horse farms are managed to mitigate negative environmental impacts. Few studies have investigated horse BMPs in the regions. More research is needed to assess the effect of horse farm management on the nation’s water quality.

What did we do?

Over the past five years, state university extension equine specialist participating on the NE-1441: Environmental Impacts of Equine Operations, multi-state project, have conducted surveys of their state equine industry. Many of the state surveys were conducted to quantify and assess the use of the equine industry’s BMPs in pasture management and erosion control and to examine potential environmental impacts.

In all cases a written survey instrument was developed and the questions were reviewed by experts in the field for content and face validity. Some of the surveys used the multiple waves, (postage) mailing techniques, while some used online survey mailings, and others used an SRS clicker feedback style quiz during a program or event [1,3,7,10]. Several states developed a large list of names and email addresses consisting of horse owners/farm managers from within their state. All used follow-up reminders sent to non-responding addresses to increase return rates. All of the state’s surveys analyzed the data for descriptive statistics. Frequencies and percentages were determined for all surveys. Cross tabulations were used to determine the relationship between management practices and farm management demographics. There is difficulty in comparing the different surveys because they are all different in methodology and in the way they were conducted and analyzed.

What have we learned?

Size and scope of the equine industry-

The New Jersey equine industry consists of 7,200 horse farms with 29% having 8 or more horses. In NJ more than 50% of the farms had 5 or fewer horses and 56% of the farms had 4.05 hectors (10 ac) or less and 18.6% had more than 8.09 ha. [10] The Maryland Equine Industry consists of 87,000 horses located on 20,200 operations, averaging 11.6 ha of pasture [3].  The Pennsylvania study averaged housing 13.4 horses on 21 ha (52.7 ac) of pasture and has 32,000 operations [7].  The Tennessee study reported the average herd size of 5, with 25.6 ac designated for pasture [6]. Forty-two percent of Vermont’s horse operation house over 9 horses on 25 ac of land.

Methods horse farms used to manage pasture quality-

Results of a Pennsylvania horse farm survey showed, that during the growing season, as many as 65% reported using a rotational pasture system and 25% continuously grazing horses [7].  A Maryland survey found that only 30% of horse farm operators used rotational grazing on their farms [3].  In a Tennessee survey, continuous grazing was practiced by 51.5% of respondents. Only 23.8% of TN respondents allowed pasture to recover to a recommended grazing height and 45.3% reported sometimes resting pastures [6].  The New Jersey survey reported 54% practicing some form of rotational grazing [9].  A study conducted on farms in Minnesota and Wisconsin revealed farms had an average stocking density of 1.75 acres per horse [1].  Designated sacrifice lots were present on 84% of farms, while the average ground cover was 88% in NJ [10]. The PA study, reported 23.8% allowed pasture to recover to a recommended grazing height and 45.3% reported sometimes resting pastures. Most respondents, 75.4% assessed their pasture vegetative cover at 80% or better, and 5% reported poor vegetative cover [7].

Methods horse farms used to manage soil and weeds-

Pasture weed problems were reported to be a major issue by 78.1% of TN owners. Half of TN farm operators (49.8%) indicated they have never performed soil fertility tests [6]. While in NJ, 31% of horse farms indicated they soil test [10]. PA horse farm operators (49.8%) indicated they have never performed soil fertility tests on their pastures, with only 25.4% testing soil every 1-3 yrs [7].  In the NJ survey 89% reported mowing pastures [10].

Methods horse farms used to manage manure-

The PA survey reported that farms composting and using compost on the farm (34.1%), hauled off the farm fresh (10.9%), spread fresh on crop/pasture fields daily (10.6%), composted and hauled off farm (7.7%), horses pastured 24 hr/d with manure harrowed or removed (16.4%), horses pastured 24 hr/d with manure never managed (7.1%) [7]. New Jersey farms, 54% indicated they spread manure on their farmland, and 74% indicated that they have a designated area for storing manure. NJ farm with greater pasture acreage were positively correlated with having manure storage [10].  The TN survey, reported, that stall waste was stored on bare ground in uncovered piles (89.8%) and either stored indefinitely or spread regularly on pastures [6].

How do farm managers receive/obtain information-

Several studies showed, horse managers are receiving most of their educational information from publications, magazine articles and the internet [7].  Therefore, Extension needs to reach horse farm managers with what we do best, factsheets, popular press articles and meetings. In the PA survey, resources participants used for information included books, magazines, publications (79.4%), internet resources (79.1%), acquaintances (65%), agencies (60.5%), multi-media (27.8%), private businesses (15.7%), and 2% reported using none. Participants indicated that the primary limitation to them altering current management practices was finances (75%), knowledge (37.5%), regulations (13.7), and an inability to obtain services (11.7%) [7].

In a South Dakota study, 29% of participants indicated that their primary need for information was regarding horse pasture management and 12% wanted to figure out how to increase grazing for horses as a primary goal. Many new SD landowners were present at an Extension event with 38% having owned their acreage for less than 3 years, and only 19% had owned their acreages for more than 10 years [5].

Future Plans

Knowledge of the current scope and nature of equine industry management practices are important when developing regulations and laws that will govern land management on equine operations. Recently, several state environmental regulations are having a direct impact on equine operations. However, horse farms frequently manage horses on fewer acres per animal unit and have the potential to pose a significant environmental risk. A NJ study reported that the rate of spreading manure decreased on farms with over 20 horses [10].

Most states surveys data shows that many horse farms are utilizing BMPs to help reduce environmental impact. However, many of these studies determined that landowners of small acreages have little knowledge of natural resources management [2,5,7].  There are several areas, such as soil testing and the use of sacrifice loafing areas in pasture management, where educational programming and cost share funding are needed to target specific BMPs underutilized by the equine industry. Nearly all survey respondents reported having some pasture and nutrient management questions [2,5,7,10].

In order to help stable managers understand the principles of sustainable best management practices, Cooperative Extension can conduct state-wide “Environmental Stewardship Short Courses.” These educational programs need to be a comprehensive series of educational programs (face-to-face meeting or webinars) to promote adoption of best management practices on equine operations. In addition, what is really needed is a comparative surveys instrument that can be used nation-wide to quantify and assess the use of the equine industry’s BMPs on horse farms.

Authors

Ann Swinker, Extension Horse Specialist, Pennsylvania State University aswinker@psu.edu

Betsy Greene, Extension Equine Specialist, University of Vermont

Amy Burk, Extension Horse Specialist, University of Maryland

Rebecca Bott, Extension Equine Specialist, South Dakota State University

Bridget McIntosh, Extension Equine Specialist, Virginia

Additional information

  1. Earing J, Allen E, Shaeffer CC, Lamb JA, Martinson KL. Best Management Practices on Horse Farms in Minnesota and Wisconsin. J Anim. Sci. 2012; 90:52.
  2. Fiorellino, N., McGrath , J., Momen, B., Kariuki, S., Calkins, M., Burk, A., 2014. Use of Best Management Practices and Pasture and Soil Quality on Maryland Horse Farms, J. Eq. Vet. Sci. 34:2, 257-264.
  3. Fiorellino, N.M., K.M. Wilson, and A.O. Burk. 2013. Characterizing the use of environmentally friendly pasture management practices by horse farm operators in Maryland. J. Soil Water Conserv. 68:34-40.
  4. Henning J, Lacefield G, Rasnake M, Burris R, Johns J, et al. Rotational grazing. University of Kentucky, Cooperative Extension Service 2000; (IS-143).
  5. Hubert, M., Bott, R.C., Gates, R.N., Nester, P.L., May 2013. Development and Branding of Educational Programs to Meet the Needs of Small Acreage Owners in South Dakota, J. of NACAA. 6:1, 2158-9429.
  6. McIntosh, B. and S. Hawkins, Trends in Equine Farm Management and Conservation Practices ASAS, Phoenix, AZ. 2/13/12.
  7. Swinker, A., S. Worobey, H. McKernan, R. Meinen, D. Kniffen, D. Foulk, M. Hall, J. Weld, F. Schneider, A. Burk, M. Brubaker, 2013, Profile of the Equine Industry’s Environmental, Best Management Practices and Variations in Pennsylvania, J. of NACAA. 6:1, 2158-9429.
  8. USDA: Aphis” VS, (1998). National Animal Health System, Highlights of Equine: part III, p. 4.
  9. Westendorf, M. L., T. Joshua, S. J. Komar, C. Williams, and R. Govindasamy. 2010. Manure Management Practices on New Jersey Equine Farms. Prof. Anim. Sci. 26:123-129.
  10. Westendorf, M. L., P. Venkata, C. Williams, J. Trpu and R. Govindasamy. 2012. Dietary and Manure Management Practices on Equine Farms in Two New Jersey Watersheds, Eq. Vet. Sci. 33:8,601-606.

Acknowledgements

The State University Extension Equine Specialist that make up the NE-1441: Environmental Impacts of Equine Operations, Multi-State Program. USDA, NRCS-CIG grant for funding the Pennsylvania project.

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Sustainable Dairy Production Housing / Manure System: Compost Bedded Loose Housing Dairy Barn


What Are Compost Bedded Dairy Barns?

In the U.S., the first compost bedded loose housing (CBP) dairy barns were developed by Virginia dairy producers in the 1980’s to increase cow comfort and longevity.  The key component of a CBP dairy barn is a large, open resting area generally bedded with sawdust or dry, fine wood shavings that is tilled to support aerobic composting. Studies in Minnesota in the early 2000’s built a knowledge base which researchers in Kentucky have utilized during the past 5 years  as the foundation for our research and extension activities on the CBP barns, herds housed within them, and assessing compost fertility. CBP barns fit within goals of sustainable agriculture for dairies with less than 500 lactating cows because of benefits to the cow (space, rest, exercise, and social interaction – Videos 1 & 2), the farmer (low investment, labor-extensive, reduced manure storage costs with composted manure under roof), milk production (milk quality, milk yield), and the environment (reduced ammonia and greenhouse gas emissions, odor and dust emissions, reduced energy consumption, improved manure fertility and flexibility to meet nutrient management plans).  Operator experiences and research results of completed and on-going CBP barn projects are presented. 

What we did

Our first activity was to assess the existing CBP barns in KY to establish the reasons for success. Fifty-five known existing CBP dairy barns in KY were visited from September 2010 to March 2011 to determine the management, barn construction details and management factors that lead to successful operation and herd improvements. Five areas of research were subsequently identified. Critics have expressed concerns about mastitis risks in barns.  Environmental mastitis has been the main concern due to the bacterial load in the CBP barn compost. A study was conducted of mastitis incidence and milk Somatic Cell Count (SCC) of CBP barns relative to “gold standard”, sand bedded free stall barns. Dairymen also wanted to have more certainty of the compost nutrient value for land application. A study was initiated to determine N and P in compost and their release for plant uptake during the first year. For one year, bed data for temperature, moisture, nutrient content by depth, and barn climate were collected to understand the seasonal climatic effects on the compost bed and how quickly these effects are seen. Finally, bed tillage, using cultivators or rototillers, was evaluated for effects on bed performance.

What we learned

Facility design, ventilation, timely addition of fresh, dry bedding, frequent and deep stirring, and avoidance of overcrowding are the keys to a good working CBP barn. Poor management may lead to very undesirable compost bed conditions, dirty cows, elevated SCC, and increased clinical mastitis incidence. Most Kentucky dairy producers listed increased cow comfort and welfare as the main benefit to the CBP barn system, while others cited increased cow cleanliness, low maintenance nature of the system, and the barn’s usefulness for special needs and problem cows. Evaluation of annual bed performance data led to development of new compost bed management strategies. Instead of using the hygiene score for cows or bed temperature, moisture content was viewed as the primary measure since it was a leading indicator of the bed before failure. The time between a good performing bed and a poor performing bed was a matter of days when the moisture content exceeds 60% – wb. The comparison of CBP barns to sand bedded freestall barns validated producers’ observations of comparable SCC and mastitis incidence prevalence in CBP barns. Finally, CBP compost added to soil differs in P dynamics depending on soil test P level. In Low Soil Test P (STP) soils the CBP tended to slowly mineralize, and like inorganic P fertilizers, was subject to adsorption. In High STP soil, P in compost was first adsorbed, but then slowly released with time.

Future plans

  1. Computational Fluid Dynamics (CFD) modeling of the compost bed management and barn design alternatives for demonstration to dairymen for planned and existing facilities.
  2. Effect of Rapid Eye Movement (REM) sleep on cow health, production and comfort.
  3. Mastitis incidence as affected by microbial ecology of the cow udder and compost bedded pack.
  4. Life Cycle Assessment (LCA) and economic analysis of system: milk production, barn, and compost disposal.

Authors

Joseph L Taraba, Extension Professor, Biosystems and Agricultural Engineering, University of Kentucky, Lexington KY – joseph.taraba@uky.edu. 859.218.4353.

Jeffery M Bewley, Associate Extension Professor, Animal Food Sciences, University of Kentucky, Lexington KY

George B Day, Adjunct Instructor, Biosystems and Agricultural Engineering, University of Kentucky, Lexington KY

Mark S Coyne, John H. Heick Professorship, Plant and Soil Sciences; University of Kentucky, Lexington KY

Michael Sama, Assistant Professor, Biosystems and Agricultural Engineering, University of Kentucky, Lexington KY

Randi A Black, PhD Graduate Student , Animal Sciences, University of Tennessee, Knoxville TN

Flavio A Damasceno, Professor (Associate), Departamento de Engenharia, Universidade Federal de Lavras, Lavras, MG – Brasil

Elizabeth A Eckelkamp, Graduate Research Assistant, Animal Food Sciences, University of Kentucky, Lexington KY

Leslie A Hammond, Graduate Research Assistant , Plant and Soil Sciences; University of Kentucky, Lexington KY

John Evans, Graduate Research Assistant, Biosystems and Agricultural Engineering, University of Kentucky, Lexington KY

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Extension Recognizes Pennsylvania Farms that Adopt Sound Management Practices Protecting Water Quality and the Environment

penn state extension environmental friendly farm signPurpose

The Environmentally Friendly Farm program was developed by Penn State Equine Extension and is designed to recognize farms that adopt environmentally sound management practices that protect water quality and the environment. The program is supported by funds from the USDA Natural Resource Conservation Service (NRCS), Conservation Innovation Grant. Strategies are employed on Environmentally Friendly Farms to maintain productive pastures, reduce soil erosion, limit nutrient runoff from animal facilities and barnyards, safely store manure, recycle nutrients, and control animal access to surface waters. Excess sediment and nutrient runoff from manure poses health threats not only to the environment, but also to animals and people. Farm managers who practice environmental stewardship maintain healthy environments for their animals, their families, and their community.

What did we do?

Farm managers can apply for the program by request a copy of the application from Penn State Equine Extension by visiting us online at http://www.extension.psu.edu/equine, emailing or calling our extension office. Second, complete the Environmentally Friendly Farm application requesting background information about the farm operation.

Next, complete the Environmentally Friendly Farm Self-Assessment Checklist. Each statement is checked “yes” if the practice is in place on the farm, “no” if the practice is not in place or “non-applicable if the statement does not pertain to the farm operation. The checklist consists of a series of statements that identify potential on-farm practices in the following areas: Environmentally Sensitive Areas, Pastures, Animal Concentration Areas, Manure Storage, and Mechanical Manure Application.

Once the paperwork has been received, a farm site visit will be scheduled. Personnel from Penn State Extension, the County Conservation District, or the Natural Resource Conservation District (NRCS) will visit farms to verify that statements made in the application and checklists are accurate. At the same time, additional information and assistance will be provided to help improve farm management and develop any necessary plans for the farm.

The farm will be recognized by the public, conservation and agricultural agencies, and other farm managers as an operation that is committed to clean water and a healthy environment. Each farm manager will receive an Environmentally Friendly Farm sign that can be displayed on the farmstead. Farms that qualify will also be given permission to use the Environmentally Friendly Farm artwork on their website, brochure, and other marketing materials. Approved farms will be listed on the Penn State Equine Extension website.

This recognition will reflect the commitment of the farm manager to environmental stewardship and can serve as a marketing tool for the farm.

What have we learned?

After personnel visited farms to verify that statements made in the application and checklists are accurate. At the same time, additional information and assistance is provided to help improve farm management and develop any necessary plans for the farm. In addition, agency personal developed a personal relationship with the farm manager. The farm managers who practice environmental stewardship maintain healthy environments for their animals, their families, and their community.

Future Plans

This program will be continued through 2016. We hope to provide additional information and assistance to help improve farm management.

Authors

Ann Swinker, Extension Horse Specialist aswinker@psu.edu

Donna Foulk, Helene McKernan, Pennsylvania State University, University Park, PA 16802

Additional information

Farms can request a copy of the application from the Penn State Extension Equine Team by visiting us online at http://www.extension.psu.edu/equine

Acknowledgements

This program was funded partly by a USDA NRCS-CIG grant.

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Analyses of Microbial Populations and Antibiotic Resistance Present in Stored Swine Manure from Underground Storage Pits

 

Why Study Antibiotic Resistance in Manure?

Antimicrobial compounds have been commonly used as feed additives for domestic animals to reduce infection and promote growth. Recent concerns have suggested such feeding practices may result in increased microbial resistance to antibiotics, which can have an impact on human health. As part of our research project we have been studying the commensal microbial populations present in stored swine manure and the swine GI tract. We have extended this work to include studies on the antibiotic resistance present in these populations.

What did we do?

Predominant microbial populations were identified by both pure culture isolations and direct 16S rDNA sequencing of total DNA from swine feces and stored manure samples. Antibiotic resistance was analyzed using similar pure culture isolation methods. Pure cultures were isolated following plating on anaerobic and aerobic media containing tetracycline, tylosin, or erythromycin. Polymerase chain reaction (PCR) analyses using primers based on a variety of antibiotic resistance genes was carries out with both pure culture isolates and total DNA from swine feces and stored manure.

What have we learned?

Results of pure culture isolation and direct 16S rDNA gene sequence analyses indicate that the bacterial populations of the swine GI tract (feces) and stored manure ecosystems are predominantly composed of anaerobic, low mole %G+C, Gram-positive bacteria, most of which represent novel genera and species. Results of antibiotic resistance gene PCR studies demonstrated the presence of a variety of tet (e.g., tetK, tetO) and erm (e.g., ermA, ermC) resistance gene classes in both anaerobic and aerobic pure cultures and total DNA from both swine feces and stored manure, as well as the identification of novel bacteria containing new resistance genes. Comparison of DNA sequences suggests that horizontal transfer of resistance genes between bacterial strains has also occurred. The data indicate that both the swine gastrointestinal (GI) tract and stored swine manure may serve as reservoirs of known and novel antibiotic resistant bacteria and resistan ce genes.

Future Plans

We are interested in developing methods to reduce antibiotic resistance in the swine GI tract and stored manure, and to determine if antibiotic resistance genes present in these ecosystems can be transferred to bacteria that may affect human health (e.g., E. coli, Salmonella, Campylobacter).

Authors

Terence R. Whitehead, Research Microbiologist, USDA-ARS- National Center for Agricultural Utililzation Research, Peoria, IL 61604 terry.whitehead@ars.usda.gov

Michael A. Cotta, USDA-ARS-National Center for Agricultural Utilization Research, Peoria, IL 61604

Additional information

Terence R. Whitehead, NCAUR, 1815 N. University St., Peoria, IL 61615 309-681-6272

USDA-ARS-NCAUR-Bioenergy Research Unit: http://ars.usda.gov/main/site_main.htm?modecode=50-10-05-20

Cotta, M.A., Whitehead, T.R., and Zeltwanger, R.L. Isolation, Characterization, and Comparison of Bacteria from Swine Faeces and Manure Storage Pits. (2003) Env. Microbiol. 5:737-745. http://onlinelibrary.wiley.com/doi/10.1046/j.1467-2920.2003.00467.x/pdf

Whittle, G., Whitehead, T.R., Hamburger, N., Shoemaker, N.B., Cotta, M.A., and Salyers, A.A. Identification of a new ribosomal protection type of tetracycline resistance gene, tet(36), from swine manure pits . (2003) Appl. Environ. Microbiol. 69:4151-4158. http://aem.asm.org/content/69/7/4151.full

Cotta, M.A., Whitehead, T.R., Falsen, E., Moore, E. and Lawson, P.A. Robinsonella peoriae gen.nov., sp. nov., isolated from a swine-manure storage pit and a human clinical source. (2009) Int. J. System. Evol. Microbiol. 59:150-155. https://pubmed.ncbi.nlm.nih.gov/19126740/

Whitehead, T.R. and Cotta, M.A. Stored Swine Manure and Swine Feces as Reservoirs of Antibiotic Resistance Genes. (2013) Lett. Appl. Microbiol. 56:264-267. http://onlinelibrary.wiley.com/enhanced/doi/10.1111/lam.12043/

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Small to Mid-Sized Dairies: Making Compact Anaerobic Digestion Feasible

Why Consider Small or Medium Digester Projects?

Anaerobic digestion (AD) is an environmentally-friendly manure management process that can generate renewable energy and heat, mitigate odors, and create sustainable by-products such as bedding or fertilizer for dairies and farmers. However, due to economics, a majority of commercially available AD technologies have been implemented on large farming operations. Since the average herd size of dairies across the country is below 200 head of milking cows, there is a need for small-scale AD systems to serve this market.

eucolino allen farmsWhat did we do?

The University of Wisconsin-Oshkosh, in collaboration with BIOFerm™ Energy Systems, installed the EUCOlino—a small-scale, mixed, plug-flow digester—onto on a 136 milking head Wisconsin Dairy. The system is pre-manufactured, containerized and requires very limited on-site construction.   This includes grading, pouring a concrete pad for the containers and electrical services installation.

Start-up and commissioning were performed after the delivery of the 64 kWe combined heat and power (CHP). The input materials consist of bedded-pack dairy manure (corn or bean stover and straw), parlor wash water, and minor additional substrates such as lactose or fats, oils, and grease.

Solid materials are dumped via bucket tractor into a hopper feeder system that uses an auger to feed substrate into the anaerobic digestion tank. Additional parlor water is piped directly into the anaerobic digestion tank and mixed with the solids to make a feedstock of approximately 13% total solids. The solids are fed hourly, which is controlled by the PLC system.

The digester has a ~30-day retention time and the biogas produced is stored in a bag above the fermenters. Biogas produced is conditioned and combusted in a CHP mounted on a separate skid. Effluent from the system is pumped directly to an open pit lagoon for storage and subsequently land applied as fertilizer. The system produces approximately 25 – 33 m3/hour of biogas, with a raw biogas quality of 52-60% CH4 and less than 700 ppm H2S.

concrete pads for installation
installation
input

What have we learned?

This project has been an important step forward in developing future small-scale anaerobic digesters across the U.S.  Notably, our installation has given us insight into balancing system economics with the size of small-scale models; the energy output of the system must exceed pre-processing energy requirements and the digester must still be large enough for the designed residence time. Our experience has shown that, while reducing the size of a digester, these requirements remain essential for an installation to economically make sense.

Additionally, challenges involved in AD at the small-scale are related to pre-processing or feedstock conveyance. Once suitable consistence or size for conveyance, anaerobically digesting the organic fraction can be relatively easy. Inconsistency of incoming feedstocks is very detrimental to the system’s stability. Additionally, exterior feedstock storage and above ground piping can limit processing potential when severe cold weather settles in. While all of these are challenges that are easily overcome with engineering, they come at a cost and that can make or break the economics at this scale.

Future Plans

For the small-scale EUCOlino to be effective in the United States, it is key to establishing a U.S.- based manufacturing location. Pre-processing needs to be well-suited to the incoming feedstock. Post-digestion products need established off-takers, for electricity generation, bedding, fertilizer, etc.

Authors

Steven Sell, Manager Application Engineer, BIOFerm™ Energy Systems beaw@biofermenergy.com

Whitney Beadle, Marketing Communications, BIOFerm™ Energy Systems

Additional information

The following publications offer additional information on the Allen Farms digester:

Readers interested in this topic can also visit our website for more information on the Allen Farms digester and other BIOFerm projects. We can also be found on Facebook, Twitter, and LinkedIn.

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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University and Anaerobic Digestion Industry Partnerships – Laboratory Testing

The anaerobic digestion (AD) industry often is in need of laboratory testing to assist them with issues related to project development, digester performance and operation, and co-digestion incorporation. This presentation will highlight laboratory procedures that can be carried out through a University partnership, including biochemical methane productivity (BMP), specific methane activity assays (SMA), anaerobic toxicity assays (ATA), solids, nutrient and elemental proximate analysis for inputs, outputs and co-products, as well as a host of other activities. The presentation will illustrate the lessons that can be learned from the results of these tests, using real-life examples of testing already completed for industry partners.

Why Provide Guidance on Laboratory Testing for Anaerobic Digestion?

Laboratory testing allows characterization of anaerobic digestion (AD) inputs, outputs, and process stability. Testing can be carried out within AD industry laboratories, and they can also be carried out through partnerships with active AD research laboratories at academic institutions. The purpose of this project was to provide a document that summarizes common laboratory procedures that are used to evaluate AD influents, effluents, and process stability and to illustrate real-life examples of laboratory test results.

What did we do? 

The overview of common laboratory procedures was written based on the need to introduce third-party AD developers and government agencies to evaluating AD outputs and process stability. The authors are practiced at performing AD laboratory tests and have expertise and valuable information concerning these types of evaluations. Following a description of each test, we included the purpose of the test and an example of how the test results can be interpreted.

What have we learned? 

Laboratory testing of AD samples is performed to determine the concentration of certain constituents such as organic carbon, volatile fatty acids, ammonia-N, organic-N, phosphorus, and methane. Contaminants can be tested for such as fecal coliform indicator pathogens, pesticides, and pharmaceuticals. Understanding the concentration of specific constituents enables informed decisions to be made about appropriate effluent management.

Biochemical methane potential (BMP) and specific methanogenic activity (SMA) tests are used to estimate the biogas and methane that can be produced from an organic waste or wastewater during AD. These tests are often used by industry during the design phase to predict total biogas output, allowing for correct sizing of engines and estimation of potential revenue.

Anaerobic toxicity assays (ATAs) test the effect of different materials on biogas production. Unknown inhibitors may reside within new feedstock materials which can lead to an unanticipated reduction in digester performance, so it is important to use ATAs to test the effect of new feedstock material on the AD system before it is used. A common example is when energy-rich organic materials are added to a digester that practices co-digestion.

Future Plans 

Future plans are to prepare an extension fact sheet about the basics of anaerobic digestion effluents and processes, including the overview of common laboratory testing used to evaluate AD influents, effluents, and process stability.

Authors

Shannon Mitchell, Post-doctoral Research Associate at Washington State University shannon.mitchell@email.wsu.edu

Jingwei Ma, Post-doctoral Research Associate at Washington State University

Liang Yu, Post-doctoral Research Associate at Washington State University

Quanbao Zhao, Post-doctoral Research Associate at Washington State University

Craig Frear, Assistant Professor at Washington State University

Additional information 

Craig Frear, PhD

Assistant Professor

Center for Sustaining Agriculture and Natural Resources

Department of Biological Systems Engineering

Washington State University

PO Box 646120

Pullman WA 99164-6120

208-413-1180 (cell)

509-335-0194 (office)

cfrear@wsu.edu

www.csanr.wsu.edu

Acknowledgements

This research was supported by funding from USDA National Institute of Food and Agriculture, Contract #2012-6800219814; and by Biomass Research Funds from the WSU Agricultural Research Center.

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Antibiotic Degradation During Anaerobic Digestion and Effects of Antibiotics on Biogas Production


Purpose 

The purpose of this research was to investigate the degradation of four animal husbandry antibiotics during anaerobic digestion (AD) and study biogas inhibition from the antibiotics. This study was designed to fill information gaps related to AD inhibition by different antibiotic classes in diluted manures received by anaerobic digesters, particularly cattle manure, and the need to more thoroughly investigate antibiotic degradation products from the AD process.

What did we do? 

We conducted AD bench-scale experiments that investigated biogas inhibition and antibiotic degradation. First, cattle manure was added to glass bottles. A known amount of antibiotic standard was added to the manure. A small amount of dilution water was added and the manure-antibiotic slurry was mixed briefly. Then, anaerobic digestion inoculum was added to the bottle. The air in the bottle was purged with nitrogen gas. Finally, the bottles were sealed and placed in an incubator set at 37°C. Biogas measurements and small liquid samples for antibiotic analysis were taken daily. At the end of the 40 day AD study, the solids were extracted to determine the amount of antibiotic adsorbed to the solids.

What have we learned? 

Results from our research showed that three out of four antibiotics degraded within 5 days of AD. Several degradation products were detected, some of which could be biologically active. The antibiotic that did not degrade was mostly found in the liquid phase of the AD reactor slurry and a small portion was adsorbed to the solids. Our results suggest that when antibiotic contaminated feedstocks are added to AD reactors, persistent antibiotics and transformation products may contaminate the liquid and solid effluents.

Our results showed the one of the antibiotics tested was more toxic to the AD process. Approximately 6.4-36 mg/L florfenicol lowered biogas production by 5-40%. Greater than 91 mg/L of the other antibiotics was needed to lower biogas production. These higher concentrations can be found in urine and feces of treated animals but they are not typical for the AD reactor following the addition of multiple feedstocks, inoculum, and dilution water. Our results suggest that there is little concern for these antibiotics to lower biogas production when cattle manure is used as an AD feedstock because the antibiotic concentration should be below inhibitory concentrations.

Future Plans 

Future research plans are to investigate the microbial population change in anaerobic digesters due to antibiotic contaminated cattle manure.

Authors

Shannon Mitchell, Post-doctoral Research Associate at Washington State University shannon.mitchell@email.wsu.edu

Craig Frear, Assistant Professor at Washington State University

Additional information 

http://www.ncbi.nlm.nih.gov/pubmed/24113548

Acknowledgements

This research was supported by Biomass Research Funds from the WSU Agricultural Research Center; and by the BioAg (Biologically Intensive Agriculture and Organic Farming) Grant Program of the Washington State University Center for Sustaining Agriculture and Natural Resources.

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Low-Power Aerators Combined with Center Pivot Manure Application at a Northeast Nebraska Hog Finishing Facility Created an Easy to Manage, Turn-Key System

trnkey animal waste management systemApplying livestock manure from lagoon storage through center pivot irrigation has long been considered a low-labor, uniform method of application that can deliver nutrients in-season to a growing crop. Three challenges with this system have been odor, pivot nozzle clogging and loss of nitrogen. A new innovation in lagoon treatment addresses these challenges. Low-power circulators were installed at a Northeast Nebraska commercial hog finishing facility and used to aerate the lagoon by moving oxygen-rich water and beneficial microbes to the bottom of the lagoon, reducing odor and potent greenhouse gases while lowering disease pathogen risk. This process preserved nitrogen and made it 40-60% more available in the first year of application. Circulation also reduced lagoon solids and bottom sludge, resulting in reduced agitation and dredging expense. Having a continuously well-mixed lagoon facilitated accurate manure nutrient sampling and consistent nutrient concentration delivery to the irrigation system. Combined with the ease of calibration of the center pivots, precision uniform nutrient application was achieved. Center pivot application had several additional advantages over tractor-based systems: less soil compaction, optimal nutrient timing during plant growth, higher uniformity, lower labor and energy costs, and eliminating impact on public roads. The circulators combined with flush barns and center pivot irrigation creates a complete turn-key manure management system.

Do Circulators Make a Difference in Liquid Manure Storage?

pumping nutrients from lagoon on korus pig siteThe purpose of the project was to evaluate the effectiveness of low powered circulators to treat livestock waste in lagoons. The objective was to evaluate how the addition of circulators to a livestock pond would change: 1. Odor levels, 2. Pivot nozzle clogging problems, and 3. Nitrogen loss.

What did we do?

A demonstration was conducted by installing five circulators on a lagoon receiving manure from a 3000 pig finisher facility. The lagoon is owned by a Lindsay customer that was already pumping the top water from the pond through pivots, but was having difficulty with plugging nozzles and was hiring a commercial pumper to agitate and pump solids. The circulators were installed in May of 2013. Starting with the day of installation and each month after through November 2013, effluent lab samples were collected, photos of the pond and effluent were taken, and odor level estimated.

comparison of manure application systems

report from Korus farm
table of report from Korus farms

The effluent was pumped through pivots where odor and nozzle clogging problems were evaluated on August 15th and December 2nd of 2013. The pond was refilled with fresh water, circulated for a few days, and re-pumped right after the August 15th event so more of the nutrients could be utilized by the crops.

What have we learned?

The benefits of using aerobic lagoons with livestock waste have been known for many years. The challenge has been finding a cost effective and reliable method to facilitate the process. The cost to run all five circulators was about $3300 per year figuring $0.10 per kWh.

The circulators facilitated the following changes in the pond:

  • Reduced dry matter in effluent to <0.4%-starting at 0.57% and ending at 0.37%
  • Greatly reduced hog hair and soybean hulls caught in the filter resulting in virtually eliminating nozzle and pressure regulator clogging on the pivot
  • Reduced solids and bottom sludge-sonar indicated a 5+ ft reduction in bottom solids in 5 months
  • Doubled 1st year availability of nitrogen-%NH4 to total N was >80% compared to average book values of 40%
  • Greatly reduced offensive manure odor-downwind from pivot applying effluent, very little odor was observed
  • Reduced disease pathogens-Total Coliform went 11,000 to 30 CFU/g & Escherichia coli went from 460 to <10 CFU/g
  • Reduced flies-virtually eliminated floating solids and fly habitat on the pond
  • Reduced severe greenhouse gasses (GHGs)
  • Generated safer and lower odor water to recycled back through the barn for manure removal

Future Plans

We would like to continue evaluating the system for more precise odor reduction ratings, nitrogen preservation during pond storage, and affect on disease pathogens.

Author

Steve Melvin, Irrigation Applications Specialist, Lindsay steve.melvin@lindsay.com

Additional information

Call Steve Melvin at 402-829 6815 for additional information.

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Manure Management Practices for Mitigation of Gaseous Emissions from Naturally Ventilated Dairy Barns


How Does Management Impact Ammonia, Hydrogen Sulfide & Greenhouse Gases In Dairy Barns?

Emissions of pollutant gases from dairy barns are dependent on manure retention time in the barn and the quality of flushing water (for manure-flush systems). Strategies for mitigating air emissions from barns thus are a function of manure management either via optimal flushing or scraping, and pretreatment of flushing water.

What did we do?      

Ammonia (NH3), hydrogen sulfide (H2S), and greenhouse gases (CO2, CH4, and N2O) emissions, under different manure collection strategies, from a naturally ventilated dairy barn housing about 850 lactating Holstein cows were measured using an on-site real-time monitoring system. The manure collection strategies evaluated included: (i) altering manure-flushing frequency, (ii) alternating flushing and scraping to remove manure, and (iii) manure solids separation system via centrifugation of the flush water.

What have we learned?

Doubling flushing frequency (every 3 h flushing) did not significantly affect NH3 emission (25.5 g cow-1 d-1) compared to the normal every 6 h flushing (24.5 g cow-1 d-1) but reduced CO2 emission by 7.3%. On the hand, H2S, CH4, and N2O emissions were 1.3, 176% and 18.5% higher at the 3-h flushing schedule than at the normal 6-h flushing schedule. Flushing at half the frequency (every 12 h) reduced H2S, CO2, and CH4 by 59.4, 19.8 and 28.5%, respectively. Alternating manure flushing and manure scraping (or vacuuming) every 6 h, decreased CO2, CH4, and N2O emissions by 13.0, 7.8 and 19.5% compared to normal 6-h manure flushing alone. Use of centrifuged water for manure flushing significantly improved emissions mitigations more than all other strategies. Emissions of all the five gases decreased by 43.0 % for NH3, 37.3 % for H2S, 1.2% for CO2, 3.7% for CH4, and 51.7 % for N2O under the latter practice.

Future Plans  

Evaluation of other manure management practices which have not previously or adequately been tested at full-scale facilities or operations.

Authors

P.M. Ndegwa, Associate Professor, Biological Systems Engineering, Washington State University, PO Box 646120, Pullman, WA 99164, USA ndegwa@wsu.edu

H.S Joo, G.M. Neerackal, X. Wang; Department of Biological Systems Engineering, Washington State University, Pullman, WA.; and J.H. Harrison; Department of Animal Sciences, Washington State University, Puyallup, WA.

Additional information

• Joo H., P. Ndegwa, G. Neerackal, X. Wang, J. Harrison, J. Neibergs. 2013. Effects of manure management on ammonia, hydrogen sulfide, and greenhouse gases emissions from naturally ventilated dairy barns. ASABE Annual International Conference. Paper number 131593447; Kansas City, Missouri, July 21 – July 24. (doi: http://dx.doi.org/10.13031/aim.20131593447).

• Neerackal, G.M., H.S. Joo, P.M. Ndegwa, J.H. Harrison. 2014. Manure-pH management for mitigating ammonia emissions from manure-flush dairy barns. ASABE and CSBE/SCGAB Annual International Meeting. Paper number 1892636; Montreal, Quebec, Canada, July 13-17.

Acknowledgements      

This study was partially supported by funds from USDA-NRCS-CIG program (Grant No. 69-3A75-11-210), and Washington State University Agricultural Research Center. 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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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Ethnobotanical Control of Odor in Urban Poultry Production: A Review


Purpose

Urban agriculture has been growing as the movement of population to the urban centers is increasing. According to FAO (2008), by 2030 majority of the population in sub sahara Africa (SSA) would be living in the urban area. Pollution from animal manure is a global concern and is much more acute and serious in countries with high concentrations of animals on a limited land base for manure disposal (Roderick, Stroot and Varel, 1998), this is the case with urban livestock production. Environmental pollution and odor complaints related to animal production have increased dramatically during the past decade (Ernest and Ronald, 2004). These odors potentially interfere with quality and enjoyment of life (Mauderly, 2002 and Albert, 2002). According to Pfost, Fulhage and Hoehne, 1999, odor complaints are more common when the humidity is high and the air is still or when the prevailing breezes carry odors toward populated areas. Inspite of the role that urban agriculture can play in pursuing the Millennium Development Goals, more specifically those, related to poverty reduction, food security, and environmental sustainability, odor from livestock still remains a major obstacle to future development. According to Obayelu 2010 there has been public’s increasing intolerance of livestock odors, hence the need to find solutions which will be ecosystem friendly. This paper will review some methods of odor control focusing on natural solutions to this problem.

What did we do?

For an odor to be detected downwind, odorous compounds must be: (a) formed, (b) released to the atmosphere, and (c) transported to the receptor site. These three steps provide the basis for most odor control. If any one of the steps is inhibited, the odor will diminish. (Chastain, 2000)

There are four general types of compounds for odor control: (1) masking agents that override the offensive odors, (2) counteractants that are chemically designed to block the sensing of odors, (3) odor absorption chemicals that react with compounds in manure to reduce odor emission, and (4) biological compounds such as enzymatic or bacterial products that alter the decomposition so that odorous compounds are not generated (Chastain, 2000). Some of these compounds are added directly to the manure while others are added to the feed. Yucca schidigera is a natural feed additive for livestock and poultry used to control odors, ammonia and other gas emissions, which can be detrimental to livestock performance. Essential oils are being promoted as effective and safe antimicrobial or antiviral (disinfectant) agents that also act as masking agents in the control of odor examples are thymol and carvacrol. Natural zeolite, clinoptilolite (an ammonium-selective zeolite), has been shown t o enhance adsorption of volatile organic compounds and odor emitted from animal manure due to its high surface area. Cai et al. (2007) reported reduction >51% for selected offensive odorants (i.e. acetic acid, butanoic acid, iso-valeric acid, dimethyl trisulfide, dimethyl sulfone, phenol, indole and skatole) in poultry manure with a 10% zeolite topical application. Treatment of broiler litter with alum was originally developed to reduce the amount of soluble phosphorous in poultry litter. However, it was also observed that using alum reduced the pH of the litter to below 6.5, and as a result, reductions in ammonia emissions from the litter have been observed.

Amendment of manure with alkaline materials such as cement kiln dust, lime, or other alkaline by-products can increase the pH to above 12.0, which limits the vast majority of microbialactivity, including odor producing microorganisms (Veenhuizen and Qi, 1993, Li et al., 1998). The effect of the addition of lime and other ONAs that alter the pH and moisture content of the waste and bedding requires further scientific research (McGahan, et al., 2002).

Dust particles can carry gases and odors. Therefore, dust control in the buildings can reduce the amount of odor carried outside. Management practices that can greatly reduce the amount of dust in poultry buildings are Clean interior building surfaces regularly, Reduce dust from feed, this can be by addition of oil to dry rations, proper and timely maintenance of feeders, augers, and other feed handling equipment. Also managing the relative humidity (RH) in poultry houses. Planting just three rows of trees around animal farms has also been proven to cut nuisance emissions of dust, ammonia, and odors from poultry houses. The use of tress around livestock facilities to mitigate odour and improve air quality has been recently reviewed by Tyndall and Colletti (2000). They concluded that trees have the potential to be an effective and inexpensive odor control technology particularly when used in combination with other odour control methods. Trees ameliorate odours by dilutio n of odour, encourage dust and aerosol deposition by reducing wind speeds, physical interception of dust and aerosols, and acting as a sink for chemical constituents of odour.

What have we learned?

The use of indigenous microorganisms for odor reduction related to livestock is being promoted under Natural farming, in this instance cultured mixtures of microorganisms consisting mainly of lactic acid bacteria, purple bacteria and yeast are used. This is already made into commercial product and marketed as effective microorganism activated solution (EMAS).

Interestingly, there is paucity of information on ethnobotanicals that are useful for odour control. Most literatures on ethnobotany focused of treatment and control of animal diseases but not on traditional control of the environment of livestock. As scientists are still working hard to develop chemical or biological additives which will eliminate or reduce odors associated with poultry wastes there is the need to survey traditional livestock owners for information that can serve for development of effective,inexpensive, efficient and suitable agent for odor control in poultry management.

Corresponding author, title, and affiliation

Oyebanji Bukola, Department of Animal Sciences, Obafemi Awolowo University, Ile-Ife, Nigeria

Corresponding author email

Oyebanji.bukola44@gmail.com

References

Albert, H. (2002) Outdoor Air Quality. Livestock Waste Facilities Handbook, Midwest Plan Service (MWPS),
Iowa State University in Ames, Iowa. Volume 18, section 3 Page 96.

Cai, L., Koziel, J.A., Liang, Y., Nguyen, A.T., and H. Xin. 2007. Evaluation of zeolite for
control of odorants emissions from simulated poultry manure storage. J. Environ. Qual.
36:184-193.

Chastain, J.P., and F.J. Wolak. 2000. Application of a Gaussian Plume Model of Odor
Dispersion to Select a Site for Livestock Facilities. Proceedings of the Odors and VOC
Emissions 2000 Conference, sponsored by the Water Environment Federation, April 16-19,
Cincinnati, OH., 14 pages, published on CD-ROM.

Ernest, F.B and Ronald, A.F.(2004) An Economic Evaluation of Livestock Odor Regulation Distances.
Journal of Environmental Quality, Volume 33, November–December 2004

FAO 2008. Urban agriculture for sustainable poverty alleviation and food security. FAO Rome

Mauderly, J.L. (2002) Health Effects of Mixtures of Air Pollutants. Air Quality and Health: State of the Science, Proceedings of the Clean Air Strategic Alliance Symposium, Red Deer, Alberta, Canada, June 3-4, 2002.

McGahan. E, Kolominska, C Bawden, K. and Ormerod. R (2002). Strategies to reduce odour emissions from Meat chicken farms Proceedings 2002 Poultry Information Exchange

Pfost, D. L., C. D. Fulhage, and J. A. Hoehne (1999) Odors from livestock operations: Causes and possible cures. Outreach and Extension Pub. # G 1884. University of MissouriColumbia.

Obayelu, A. E 2010. Assessment Of The Economic And Environmental Effects Of Odor Emission From Mechanically Ventilated Livestock Building In Ibadan Oyo State Nigeria. International Journal of science and nature VOL. 1(2) 113-119

Tyndall, J. and J. Colletti. 2000. Air quality and shelterbelts: Odor mitigation and livestock production a literature review. Technical report no. 4124-4521-48-3209 submitted to USDA, National Agroforestry Center, Lincoln, NE.

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. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

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