This webinar discusses the science and economics behind the use of worms in the processes of composting (i.e., vermicomposting) and treatment of wastewater and manure liquid waste stream (vermifiltration). This presentation was originally broadcast on May 20, 2022. Continue reading “Use of Vermifiltration as a Tool for Manure Management”
Characterization of Innovative Manure Treatment Components
Purpose
Improvements in manure treatment/nutrient management are an important need for dairy farms to move substantively towards sustainability. This project quantifies several individual manure treatment components and component assemblies targeted to address farm/environment needs. Project outcomes should help dairy farms to make better-informed decisions about manure/nutrient management systems.
Societal demand for farms to reduce their environmental impact is driving the need for improved and cost-effective manure/nutrient management options. Dairy farms may need advanced manure treatment systems to be economically, environmentally, and societally sustainable.
What Did We Do?
Specific treatments being evaluated include anaerobic digestion, active composting, sequencing batch reactors, solid-liquid separation systems including, screw press separation, dissolved air floatation, centrifuging, and solid treatment systems including bedding recovery units and pelletization. We are working with a farm that has an anaerobic digester and screw press separators. They have been planning to install a Dissolved Air Flotation (DAF) system. The farm was approached with an in-vessel composting technology “active composting” to determine if it could effectively convert portions of the digested separated liquid flow to a stabilized solid that could be pelletized and exported, while the liquids could be further treated to become dilute enough to be spray irrigated on a limited acreage.
What Have We Learned?
We learned that although the active composting process was able to quickly produce stabilized high solid content material from a variety of mixes of digested separated liquid and dried shavings, the energy needed ranged from $9 to $14 per cow per day. Through volume/time calculations, the pumping system from the reception pit to the digester and the post digestion pit to the separators varied although the % solids were consistent. Doppler flow meters purported to be able to measure manure did not give consistent volume results. Screw press solid liquid separation can result in a bedding product with relatively low moisture (60%) from anaerobically digested dairy manure. Determining an optimum manure treatment system for dairy manure will be difficult given the variability from farm to farm.
Future Plans
Specific treatments yet to be evaluated include: anaerobic sequencing batch reactors, solid liquid separation systems including dissolved air floatation (DAF), centrifuging, and solid treatment systems including bedding recovery units (BRU) and pelletization. Covid supply chain issues and travel restrictions have slowed progress. The DAF system can be directly analyzed as it is installed on the dairy. A neighboring farm has a BRU that will be sampled and analyzed. Data from a centrifuge and pelletizer will be obtained from the literature. Putting the process in a treatment train will be explored on a spreadsheet.
Authors
Peter Wright, Agricultural Engineer, PRO-DAIRY, Cornell University
Corresponding author email address
Additional authors
Lauren Ray, Environmental Energy Engineer, PRO-DAIRY, Cornell University
Curt Gooch, Emeritus Senior Extension Associate, Cornell University
Additional Information
We have completed several fact sheets including Manure Basics, Advanced Manure Treatment – Part 1: Overview, Part 2: Phosphorus recovery technologies, Part 3: Nitrogen recovery technologies, and Part 4: Energy extraction. These are available at: https://cals.cornell.edu/pro-dairy/our-expertise/environmental-systems/manure-management/manure-treatment
Publications: Peter Wright, Karl Czymmek, and Tim Terry “Food waste coming to your farm? Consider where the nutrients go and manure processing for nutrient export” PRO-DAIRY The Manager, contained in Progressive Dairy Vol. 35 No. 5 March 12, 2021
Acknowledgements
This work was supported by a joint research and extension program funded by the Cornell University Agricultural Experiment Station (Hatch funds) and Cornell Cooperative Extension (Smith Lever funds) received from the National Institutes for Food and Agriculture (NIFA,) U.S. Department of Agriculture. 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. New York State Pollution Prevention Institute (NYSP2I) at the Golisano Institute for Sustainability (GIS) paid for the sampling that was funded by a grant to RIT from by the Environmental Protection Fund as administered by the NYS Department of Environmental Conservation.
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. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.
Active participation in livestock and poultry sustainability initiatives
Purpose
Whether at the farm, integrator or industry level, sustainability programs have unique goals, metrics and approaches. In many cases, there is no definitive path for meeting long-term goals, but in the ambiguity is opportunity. Meeting sustainability goals will take a community of persons on and off farm willing to support measurements, communication and technology development. This session builds on the Livestock and Poultry Environmental Learning Community’s (LPELC) September 2021 Webinar, Industry Initiatives for Environmental Sustainability – a Role for Everyone.
This Waste to Worth workshop features small and large group discussions to identify modes for active participation in livestock and poultry sustainability initiatives.
What Did We Do?
Industry-led sustainability programs are in various stages of charting a destination for environmental metrics, like greenhouse gas emissions, water quality, water use, etc. However, with respect for the range of individual farm resources, climates and systems, there is no prescriptive path.
As farmers and organizations chart their own sustainability journey, there is a need for on-farm baseline metrics, goal setting, and technology guidance. LPELC’s mission is to provide on-demand access to “the nation’s best science-based resources that is responsive to priority and emerging environmental issues associated with animal agriculture” (LPELC.org). The LPELC is in a strong position to share science and support communication efforts. However, like sustainability journeys, LPELC needs a roadmap.
This workshop will illuminate what resources are currently available, knowledge, technology and communication gaps, and how LPELC members can support on-farm sustainability initiatives. Participants will collectively shape a logic model for a “Community of Support for Producer Engagement in Livestock Industry Environmental Sustainability Initiatives”.
What Have We Learned?
A summary of the workshop results will be shared following the conference.
Future Plans
We intend the workshop results to foster stronger networks and collaborative directions for advancing on-farm sustainability initiatives. We aim for short, medium and long-term outcomes that include stronger understanding of current efforts within the livestock industries and LPELC, along with support mechanisms for decision making and funding opportunities.
Authors
Erin Cortus, Associate Professor and Extension Engineer, University of Minnesota
Corresponding author email address
ecortus@umn.edu
Additional authors
Marguerite Tan, Director of Environmental Programs, National Pork Board; Hema Prado, Director of Sustainability, American Egg Board; Michelle Rossman, Vice President – Environmental Stewardship, Dairy Management Inc.
Additional Information
Webinar – Industry Initiatives for Environmental Sustainability – a Role for Everyone https://lpelc.org/industry-initiatives-for-environmental-sustainability-a-role-for-everyone/#more-33017
US Pork Industry Sustainability Goals https://www.porkcares.org/pork-industry-sustainability-goals-and-metrics/
US Roundtable for Sustainable Poultry https://www.us-rspe.org/
US Dairy Net Zero Initiative https://www.usdairy.com/getmedia/89d4ec9b-0944-4c1d-90d2-15e85ec75622/game-changer-net-zero-initiative.pdf?ext=.pdf
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. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.
Manure Treatment Technology Adoption by Swine and Dairy Producers: Survey Feedback
Purpose
Sound management of manure is essential to optimize its benefits for soil health and crop production, and to minimize costs and environmental risks. Along with changes in farm scale and practices, modern farms are increasingly looking to process or treat manure to address problem areas and to take advantage of market opportunities on their operations. A variety of manure treatment technologies are available and new technologies continue to be developed for managing nutrients, solids, energy, water, and other components of manure. But, while these new treatment technologies hold potential to improve the environmental, economic, and social sustainability of livestock and poultry production, questions remain regarding producer adoption of treatment systems on their operations. To improve our understanding of decision-making processes employed when producers evaluate and adopt manure treatment technologies, the authors conducted a survey aimed at dairy and swine producers in the Midwest.
What did we do?
Two surveys were developed, one tailored to dairy producers and one for swine producers. All operation sizes and production systems were included. The surveys were administered using Qualtrics, an online survey platform. Questions asked covered manure-related practices in animal facilities, manure handling, and land application. Additional questions asked producers to prioritize their needs for manure treatment, factors influencing technology selection, current technologies being utilized, and principal barriers for adoption. Respondents were asked to select up to three critical outcomes for their farms’ manure treatment technologies, the most influential factors (or technology characteristics) for manure treatment adoption, and the main barriers for technology adoption. The authors collaborated with Nebraska Extension and with state producer associations to reach swine and dairy producers in Nebraska and other Midwest states, with the survey first launched in the fall of 2021. Magazine articles, radio programs, listservs, and social media were used to promote the surveys.
Responses were analyzed using descriptive methods. Eighteen respondents provided information to characterize seven swine farms and ten dairy operations. Swine respondents had farms in Nebraska (7), Iowa (2), and Ohio (1). For dairy, 7 of the farms were in Nebraska and 1 was in Minnesota. Swine farm systems were divided between the ones that had farrowing (farrow-to-finish and farrow-to-wean systems) and the ones without it (grow-to-finish and wean-to-finish systems) (Table 1). Respondents were asked to provide insights for their farms’ primary manure management systems. A dairy operation’s primary manure management system was defined as the one receiving manure from the lactating cows. For swine, the primary manure management system received manure from the gestation sows or the finishing herd. For both swine and dairy, secondary systems were defined as utilizing separate storage and handling facilities.
| Species and herd type | Number of farms | Herd size – average | Herd size – range |
|---|---|---|---|
| Dairy – lactating cow herd | 8 | 933 | 30 to 2,150 |
| Swine (farrowing) – sow herd | 4 | 2,762 | 250 to 7,500 |
| Swine (finishing) – finisher herd | 5* | 23,600 | 1,200 to 70,000 |
| Note: *One finishing farm did not share its herd size information. | |||
What have we learned?
The dairy and swine farms demonstrated differences in manure treatment needs and consequently adopted different treatment technologies (Figures 1 and 2).
FTF = farrow-to-finish
PSOP = partially slotted open pens
PP = pull-plugs
FTW = farrow-to-wean
ISWPSF = individual stalls w/partial slotted floor
DP = deep pits
GF-F = grow-finish or finishing
ASFB = all slotted-floor building
FL = flushing
WTF = wean-to-finish
CH = chemicals
AE = aeration
LA = lagoons
AD = anaerobic digestion
CO = composting
CS = corn stalks
Sd = sedimentation
DD = direct drying
Mch = mechanical
TL = treatment lagoon
Co = composting
Stt = sand settling lane or basin
AE = aeration
NS = no separation
AD = anaerobic digestion
The most-used technologies in the primary manure management system for each industry were: mechanical separation, sand settling lanes, and sedimentation basins for dairy farms; and addition of chemicals, treatment lagoons, and composting for swine operations (Figure 3).
Allowing water to be reused and exporting nutrients were the primary desired outcomes of implementing manure treatment technologies for dairy and swine farms, respectively (Figure 4). Accordingly, 6 of 7 dairy farms were recycling water in their operations, while only 1 out of 10 was doing so on the swine side.
Diverse factors influenced the selection of the implemented technologies in both livestock operations. Low management demand, low maintenance, “performs best functionally” (best performance achieving the desired goals of manure treatment), and low initial cost are among the most-mentioned factors (Figure 5).
Swine and dairy farmers identified initial cost, operational cost, and return on investment as the primary barriers to future technology adoption (Figure 6). Management demand was another important barrier among swine producers.
None of the survey respondents used membranes, electrochemical precipitation, or gasification technologies, demonstrating that cutting-edge manure treatment technologies are being more slowly adopted by regional livestock producers. The high cost and potential high management demand of these technologies could be barriers for their adoption.
Future plans
Our research work has moved into qualitative exploration. Focus groups will be held with swine and dairy producers, where they will discuss and share their manure treatment needs and desired outcomes from new treatment options. These activities will be organized online and will allow producers to share their manure management perspectives for the present and future. The results of our surveys and focus groups are being used to inform a decision-support tool being developed as part of the Management of Nutrients for Reuse (MaNuRe) project. Our findings will also be used to help develop extension programs that meet the needs of producers for manure management in Nebraska and neighboring states.
Authors
Juan Carlos Ramos Tanchez, Graduate Research Assistant, University of Nebraska-Lincoln.
Corresponding author email address
jramostanchez2@huskers.unl.edu
Additional authors
Richard Stowell, Professor of Biological Systems Engineering, University of Nebraska-Lincoln.
Amy Schmidt, Associate Professor of Biological Systems Engineering, University of Nebraska-Lincoln.
Acknowledgements
Funding for this effort came from the USDA NIFA AFRI Water for Food Production Systems program, grant #2018-68011-28691. The authors would like to express gratitude to Dr. Teng Lim and Timothy Canter (University of Missouri), Mara Zelt, and Lindsey Witt-Swanson (University of Nebraska-Lincoln) for their relevant support to this study. We would also like to thank the staff at the Nebraska Pork Producers Association and the Nebraska State Dairy Association for their collaboration on our research.
Cleanout for Lagoons and Anaerobic Digesters
In this webinar, presenters share their expertise in sampling and cleanout for lagoons and anaerobic digesters and considerations in planning these operations. This presentation was originally broadcast on January 21, 2022. Continue reading “Cleanout for Lagoons and Anaerobic Digesters”
California’s Efforts to Reduce Greenhouse Gases from Dairy and Livestock Operations
This webinar discusses two programs in California, administered through the California Department of Food and Agriculture (CDFA), that provide financial incentives to dairy and livestock producers to reduce methane emissions from on-farm manure management. This presentation was originally broadcast on August 16, 2019. More… Continue reading “California’s Efforts to Reduce Greenhouse Gases from Dairy and Livestock Operations”
Development and Application of the Newtrient Evaluation Assessment Tool (NEAT): A Methodology for Comparing Manure Treatment Technologies
The recent development of the Newtrient on-line catalog (www.newtrient.com/Catalog/Technology-Catalog; see accompanying conference proceedings about the catalog) revealed the need to establish a set of environmental and farm operational based critical indicators (CIs). The indicators are useful in identifying manure treatment technologies that primarily best address dairy farm environmental sustainability but include some social aspects.
What did we do?
The Newtrient Technical Advancement Team, comprised of academic and industry professionals in dairy manure management, developed and implemented a novel methodology that identifies technologies that best address dairy farm sustainability mainly from an environmental but also from a social perspective. A project-amended process used by the International Organization for Standardization (ISO) was used as the basis for methodology development; the methodology is known as the Newtrient Evaluation and Assessment of Technology (NEAT) process.
For this work, six specific CIs were selected based on key environmental challenges/opportunities facing the dairy industry; they are: nitrogen recovery, phosphorus recovery, liquid manure storage requirements, greenhouse gas reduction, odor reduction, and pathogen reduction. A literature search was performed to evaluate 20 manure treatment technology types under five technology categories (Table 1).
A scoring system relative to the baseline condition of long-term (anaerobic) manure storage was developed and applied to each technology type and an appropriate relative score for each CI was determined. The NEAT results are presented in an easy to understand dashboard called the NEAT Matrix (Figure 1).
What have we learned?
Use of the NEAT process across the 20 manure treatment technology types confirms that there is no single technology type that can address all the environmental and operational indicators. An integrated manure management system that is comprised of strategically selected technologies may be assembled to move each dairy farm toward sustainability.
| Table 1. Technology categories and associated manure treatment technology types evaluated using the Newtrient Evaluation and Assessment of Technology (NEAT). | |
|---|---|
| Technology Category | Evaluated Technology Types |
| Primary solid-liquid separation |
|
| Secondary solid-liquid separation |
|
| Physical and biochemical stabilization |
|
| Nutrient recovery |
|
| Energy recovery |
|
Future Plans
Future research in this area will continue to focus on using NEAT to evaluate integrated manure management systems designed specifically to achieve farm goals/needs.
Corresponding author, title, and affiliation
Curt Gooch, Environmental Systems Engineer, PRO-DAIRY Dairy Environmental System Program, Dept. of Animal Science, Cornell University.
cag26@cornell.edu
Other authors
Mark Stoermann (Newtrient, LLC), Garth Boyd (Context), Dana Kirk (Michigan State University), Craig Frear (Regenis), and Frank Mitloehner (UC Davis).
Additional information
Additional project information, is available on the Newtrient website: www.newtrient.com
Acknowledgements
Newtrient, LCC and the paper authors thank the following supporters of Newtrient: Agri-Mark, Inc., Dairy Farmers of America, Inc., Dairy Management Inc., Foremost Farms USA, Land O’Lakes, Inc., Maryland Virginia Milk Producers Cooperative Association, Inc., Michigan Milk Producers, National Milk Producers Federation, Prairie Farms Dairy, Inc., Select Milk Producers, Inc., Southeast Milk, Inc., St. Albans Cooperative Creamery, Tillamook County Creamery Association, and United Dairymen of Arizona
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. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.
Considerations in Evaluating Manure Treatment Systems for Dairy Farms
Advanced manure treatment may become a major system on some dairy farms in the future. Reducing the impacts of excess nitrogen and or phosphorous may be necessary on farms with a limited or remote land base. Additional treatments to recover solids, extract energy, concentrate nutrients, reduce odors, reduce the mass/volume, and/or reduce pathogens may become more of a priority as farms seek to move toward sustainability. Potential systems should be evaluated from many perspectives including on an economic and effectiveness basis. There are many variables to consider in evaluating a manure management system. Potential systems should be selected based on many criteria including: operational history, operational reliability, market penetration, capital cost, O&M cost, value proposition, and vendor information and documentation including case studies and customer reviews.
What did we do?
Manure management formally started in the second half of the 20th century with the development and implementation of the water quality best management practice (BMP) of long-term manure storage. Storage provides farms with the opportunity to recycle manure to cropland when applied nutrients can be more efficiently used by the crop. Many long-term manure storages were built to improve nutrient recycling and minimize risk. In some cases, anaerobic lagoons were built to both reduce the organic matter spread to fields and store manure. Simultaneously as poultry and livestock consolidation escalated, more manure storages were built and their volume increased to reflect the recognized need to store manure longer. Cooperative Extension, Soil and Water Conservation Districts and Natural Resources Conservation Service have assisted in providing planning, design, construction and maintenance of these manure storage systems.
What have we learned?
Many lessons have been learned from storing manure long-term. They include, but are not limited to:
-
- While storing manure long-term reduces water quality impairment, it also produces and emits methane, a greenhouse gas. Greenhouse gases are reported to contribute to global warming. The US dairy industry is under attack by some because of this, and it is likely that the decline in fluid milk sales has, in some part, been affected by this. The lesson learned here is that the implementation of BMPs can have unintended consequences; therefore, all future BMPs need to be thoroughly vetted before substantial industry uptake happens in order to avoid undesirable unintended consequences.
- Larger long-term storages are better than short-term (smaller) ones. Storages that store manure for a longer period of time provide farms with increased flexibility when it comes to recycling manure to cropland.
- Long-term storages can emit odors that can be offensive to neighbors and communities. Farms have adopted improved manure spreading practices, namely direct incorporation, to reduce odor issues but incorporation doesn’t work well on some crops. Some farms have also adopted anaerobic digestion as a long-term storage pre-treatment step in order to reduce odor emissions from storage and land application.
- Substantial precipitation can accumulate in long-term storages located on farms in humid climates. Increased storage surface area (generally an outcome of building larger storages) results in more precipitation to store and handle as part of the manure slurry. Every acre-foot of net perception results in 325,900 gallons of additional slurry to store and spread. If each manure spreader load is 5,000 gallons, then this means 65 additional loads are required.
- Neighbors of larger farms are more sensitive to intensive truck traffic than regular but low-level truck traffic. Long-term storages require intensive, focused effort to empty and the over the road truck traffic can be offensive in some farm locations.
- Insufficient storage duration results in the need to recycle manure to cropland during inopportune times and thus may not be contributing to the BMP goal. Fall spreading is still required on many farms; however, it also may be unlikely that a sufficient spring planting window exists for farms to spread all their manure in the spring, avoid compacting wet soils and also get spring crops planted in time.
- Where longer term storage duration and or incorporation of the manure to prevent odor emissions is needed to facilitate spring and summer manure spreading, farms may have more manure nutrients than needed to meet crop demand.
Future Plans
The above lessons learned support the need for advanced manure treatment systems on some farms that can also be used as the basis for considerations that should be included when evaluating all manure treatment systems. It is important that the manure treatment equipment/system components and the overall system address the farm need(s) as best as possible. A challenge with evaluating the existing manure treatment equipment available to the farmer is the lack of performance and economic data. Comparatively, advanced manure treatment (we define this as treatment above basic primary solid-liquid separation) is in its infancy stage of adoption and thus little field performance data exists. Our plans are to continue (as funding allows) to perform more on-farm manure treatment system evaluations and to report facts to our US dairy industry stakeholders.
Corresponding author, title, and affiliation
Curt Gooch, Environmental Systems Engineer, PRO-DAIRY Dairy Environmental System Program, Dept. of Animal Science, Cornell University
cag26@cornell.edu
Other authors
Peter Wright, Agricultural Engineer, PRO-DAIRY Dairy Environmental System Program, Dept. of Animal Science, Cornell University
Additional information
Additional project information, including reports about on-farm assessment of manure treatment systems, is available on the Dairy Environmental System Program webpage: www.manuremanagement.cornell.edu
Acknowledgements
New York State Department of Agriculture and Markets for their continued financial support of the PRO-DAIRY Program, the New York State Energy Research and Development Authority (NYSERDA) for funding many on-farm sponsored projects, and the US dairy farmers who have collaborated with us for over three decades.
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. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.
Impact of Anaerobic Digestion on Solids, Nitrogen, Phosphorous, Potassium, and Sulfur Concentrations of Swine Manure
Anaerobic digestion of swine manure is a treatment process that can be used to reduce odor emissions, generate bioenergy, and reduce methane emissions. Studies and models are available that can be used to quantify methane production, and volatile solids (VS) reduction rates. Few provide information on the plant nutrient contents of digested manure. Such information is needed to develop nutrient management plans to use digester effluent to produce crops, biomass, or as a nitrogen source for making compost in an environmentally responsible manner. The objective of this study was to observe the reductions and transformations of solids (TS, VS), nitrogen, phosphorous, potassium, and sulfur resulting from anaerobic digestion.
What did we do?
Fresh swine manure was obtained from the gestation barn at the Starkey Swine Center at Clemson University (Figure 1), and large supernatant samples were obtained from the lagoon on-site. The solid manure from the gestation floor was diluted with supernatant from the lagoon to obtain three total solids (TS) concentrations. The target total solids concentrations were 1%, 1.2%, and 2%. Dilutions in this range were selected because they were representative of common ranges of liquid swine manure removed from modern production facilities. This also provided three levels of organic load (OL) that was defined by the VS concentration of the mixtures (g VS/L). The dilutions that were actually achieved were 0.9%, 1.2%, and 1.9% total solids with volatile solids (VS) concentrations of 6.10, 9.05, and 13.75 g VS/L.
Since lagoon water was used for dilution in a manner similar to the operation of a recycled flush system no additional seed material was needed. The microorganisms needed for anaerobic digestion already existed in the manure.
Batch Anaerobic Digestion
The three mixtures of swine manure and lagoon water were anaerobically digested using 1.8L batch reactors that were maintained at 35 C in a heated water tank as shown in Figure 2. Three 1.8L bottles were used for each of the three liquid swine manure mixtures to give a total of 9 reactor bottles. Complete details of the batch method used is provided by Chastain and Smith (2015).
The reactor bottles were digested for 56 to 74 days. The pH of the bottles was measured daily and was used as the primary parameter to monitor digestion progress. Biogas production was also monitored by collecting it in 3-L Tedlar® bags, one per reactor bottle. The day on which the gas collection bags were emptied was recorded and provided a secondary parameter to determine when digestion was complete. Anaerobic digestion is a two phase process. During the first phase, called the acid forming phase, microorganisms create volatile fatty acids (VFA) and the pH falls rapidly to 6 or less. During the second phase the methanogens increase in population and consume the VFAs causing the pH to rise. Digestion was complete once the pH hovered around 7.5 for several days, and biogas was no longer produced. A graph of the variation in pH for the reactors is provided in Figure 3.
Solids and Plant Nutrients Measured Before and After Anaerobic Digestion
Well-mixed samples of the three liquid swine manure mixtures were obtained before and after anaerobic digestion. Since nitrogen and phosphorous in swine manure exist in soluble and organic forms the reductions and transformations of soluble and organic forms of these nutrients were also observed. The samples were analyzed to determine the following using standard techniques:
- The total solids (TS),
- The fixed solids (FS) or ash content,
- The volatile solids (VS = TS – FS)
- Total Kjeldahl nitrogen (TKN = Org-N + TAN)
- Total ammonical nitrogen (TAN = NH4+-N + NH3– – N),
- Organic nitrogen (Org-N = TKN – TAN),
- Nitrate nitrogen (NO3-N),
- Mineral nitrogen (Min N = TAN + NO3-N),
- Total nitrogen (TN = TKN + NO3-N),
- Total phosphorus (TP),
- Soluble phosphorous (Sol-P),
- Total potassium (TK), and
- Sulfur (S).
What did we learn?
The first important observation was related to the completeness of anaerobic digestion. The mean VS reduction ratio (g VS destroyed/g VS added) for all nine reactors was measured, and was 0.62 on the average. This and was in excellent agreement with the literature value of 0.63 for swine manure (Hill, 1991), and indicated that anaerobic digestion was complete. The rate of TS destruction was 0.45 g TS destroyed / g TS added.
The second set of observations were related to the impact of anaerobic digestion on nitrogen. The mass of total N was not changed by anaerobic digestion, but the mass of organic nitrogen was decreased by 36% as it was mineralized to TAN. The TAN was increased by a factor of 1.84, and the mineral N (TAN + NO3-N) was increased by a factor of 1.8 on the average. The initial nitrate-N concentrations were small and evidence of denitrification was observed as indicated by a reduction in nitrate-N by 59%. The impact of N transformations was to increase the fraction of total-N that was in the total ammonical form from 33% before digestion to 59% after digestion which highlights the need to store and land apply anaerobically digested manure so as to reduce ammonia volatilization.
Anaerobic digestion was also observed to have mixed results on the mass of P, K, and S. The mass of total-P was not significantly impacted by anaerobic digestion. On the average, 73% of the soluble-P was converted to organic P by microbial activity, and was believed to remain in the microbial biomass. There was no impact on TK by digestion as expected. The mass of S was reduced by 7% on the average presumably by the formation of small amounts of H2S.
Authors
- John P. Chastain, Ph.D. Professor and Extension Agricultural Engineer, Clemson University, Department of Agricultural Sciences, Agricultural Mechanization and Business Program, McAdams Hall, Clemson, South Carolina 29634 USA. jchstn@clemson.edu 1-864-656-4089
- Bryan Smith, BSAE, MSCE, Area Extension Agent – Agricultural Engineer, Clemson Extension Service, 219 West Laurens Street, Laurens, South Carolina 29360 USA.
References
Chastain, J.P. and W.B. Smith. (2015). Determination of the Anaerobic Volatile Solids Reduction Ratio of Animal Manure Using a Bench Scale Batch Reactor. Presented at the 2015 ASABE Annual International Meeting. Paper No. 152189216. ASABE, 2950 Niles Rd., St. Joseph, MI 49085-9659
Hill, D.T. (1991). Steady-State Mesophilic Design Equations for Methane Production from Livestock Wastes. TRANSACTIONS of the ASAE, 34(5):2157-2163.
Acknowledgements
This study was supported by the Clemson Extension Confined Animal Manure Managers Program and by a grant from the South Carolina Energy Office.
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. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.
Cataloging and Evaluating Dairy Manure Treatment Technologies
Proceedings Home | W2W Home 
Purpose
To provide a forum for the introduction and evaluation of technologies that can treat dairy manure to the dairy farming community and the vendors that provide these technologies.
What Did We Do?
Newtrient has developed an on-line catalog of technologies that includes information on over 150 technologies and the companies that produce them as well as the Newtrient 9-Point scoring system and specific comments on each technology by the Newtrient Technology Advancement Team.
What Have We Learned?
Our interaction with both dairy farmers and technology vendors has taught us that there is a need for accurate information on the technologies that exist, where they are used, where are they effective and how they can help the modern dairy farm address serious issues in an economical and environmentally sustainable way.
Future Plans
Future plans include expansion of the catalog to include the impact of the technology types on key environmental areas and expansion to make the application of the technologies on-farm easier to conceptualize.
Corresponding author name, title, affiliation
Mark Stoermann & Newtrient Technology Advancement Team
Corresponding author email address
Other Authors
Garth Boyd, Context
Craig Frear, Regenis
Curt Gooch, Cornell University
Danna Kirk, Michigan State University
Mark Stoermann, Newtrient
Additional Information
Acknowledgements
All of the vendors and technology providers that have worked with us to make this effort a success need to be recognized for their sincere effort to help this to be a useful and informational resource.
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