Anaerobic Co-digestion of Agro-industrial Feedstocks to Supplement Biogas Produced from Livestock Manure

Purpose

Anaerobic digestion (AD) is commonly used in agriculture to break down livestock manure and produce a sustainable source of energy by producing biogas, which is predominantly methane. Digestion of livestock manure can be supplemented with additional agricultural or industrial organic waste, potentially adding sources of revenue to the farm or digestion facility through tipping fees and additional biogas production. However, quantifying the anticipated impact on digester performance and operation is challenging, particularly as some potential feedstocks have not been studied previously. Understanding how a feedstock might impact a digester’s performance is critical, as digester upsets can lead to loss of revenue or even digester failure.

What Did We Do?

We conducted a set of mono-digestion biomethane potential experiments of several feedstocks currently in use at an agricultural AD facility that accepts mixed industrial waste streams in addition to digesting beef manure. The mono-digestion studies used triplicate 1-L working volume batch digesters which ran for 30-38 days. We tested beef manure, off-spec starch from food manufacturing, slaughterhouse wastewater treatment sludge, waste activated sludge from a corn processing facility, soap stock from glycerin refining, filter press slurry from a food grade water treatment facility, and food waste dissolved air flotation sludge. We also included a treatment for the effluent from the digester’s ammonia recovery system and a mixture of all the feedstocks at the same time. A blank (inoculum only) and positive control (cellulose with inoculum) digester were included as controls. This set of studies is described here as Experiment 1 (E1).

We then conducted a set of co-digestion biomethane potential tests combining the manure pairwise with some of the industrial feedstocks, specifically starch, slaughterhouse waste, soap stock, and filter press slurry (Experiment 2 or E2). These combinations were made at two different ratios of the two feedstocks. The first set of treatments combined the manure and an additional substrate at a 1:1 ratio on a volatile solids basis. The second set of treatments combined the feedstocks proportional to the amounts commonly used in the AD facility providing the materials. A final treatment pairing starch and soap stock at a 3:1 ratio was also included. These co-digestion treatments were conducted in triplicate alongside a single mono-digestion treatment of each feedstock for comparison. Finally, we examined the potential synergistic or antagonistic impacts of these combinations on methane yield and production rate. This was done by comparing the measured methane production at each time point compared to the expected methane production if the feedstocks each contributed additively to the methane production.

What Have We Learned?

Figure 1 shows the cumulative specific biogas production on a volatile solids basis for the mono-digestion experiment (E1). Some feedstocks, such as soap stock and slaughterhouse waste, experienced a substantial lag phase at the beginning of the experiment, which may have been due to the high levels of lipids and proteins.

Figure 1: Average biogas production of all treatments during mono-digestion experiment (Experiment 1).

During the co-digestion experiment (E2), we observed both total yield and kinetic synergy in all treatments. Only two digesters (one of the replicates from the starch and manure proportional treatment and one from the starch and soap stock treatment) produced substantially less (<30%) methane than would be expected for an additive effect for more than one day. This effect can be seen in Figure 2, which shows the cumulative methane curves (corrected for inoculum contribution and averaged over the three replicates) of the mono-digestion digesters for manure and starch individually and the curves for both co-digestion treatments using both manure and starch. Figure 3 shows the same curves for the co-digestion of manure and slaughterhouse waste. These co-digestion treatments show that combining the feedstocks causes an increase in methane production at a faster rate. They also show that co-digestion alleviates the lag phase experienced by the slaughterhouse waste.

Figure 2: Cumulative specific methane production for manure (F1) and starch (F2). F1 + F2 Eq = 1:1 ratio of VS; F1 + F2 Pr = ratio of VS is proportional to what full-scale digester receives.
Figure 3: Cumulative specific methane production for manure (F1) and slaughterhouse waste (F3). F1 + F3 Eq = 1:1 ratio of VS; F1 + F3 Pr = ratio of VS is proportional to what full-scale digester receives.

Future Plans

We plan to continue exploring the impact of co-digestion on methane yield and production rate by using additional combinations of these feedstocks and exploring the impact of macromolecular composition (percentages of carbohydrates, proteins, and lipids) on synergistic effects. These results will help inform current or future agricultural AD operators regarding the use of co-digestion feedstocks for optimal energy production and best practices in selecting new feedstocks for co-digestion.

Authors

Jennifer Rackliffe, Graduate Research Fellow, Purdue University

Corresponding author email address

jracklif@purdue.edu

Additional authors

Dr. Ji-Qin Ni, Professor, Purdue University; Dr. Nathan Mosier, Professor, Purdue University

Additional Information:

https://www.sare.org/wp-content/uploads/2021-NCR-SARE-GNC-Funded.pdf

Acknowledgements:

This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under agreement number 2020-38640-31522 through the North Central Region SARE program under project number GNC21-334. USDA is an equal opportunity employer and service provider. 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. We also thank Purdue’s Institute for Climate, Environment and Sustainability for supporting the dissemination of this work. Finally, we acknowledge the assistance of Gabrielle Koel, Kyra Keenan, Amanda Pisarczyk, and Emily McGlothlin in conducting the laboratory work.

 

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.

Evaluating Costs and Benefits of Manure Management Systems for a Decision-Support Tool

Purpose

The purpose of the decision-support tool is to help livestock producers understand the costs of implementing new technology and the potential benefits associated with nutrient and water recovery, and how these compare across systems. Livestock agriculture is under increased scrutiny to better manage manure and mitigate negative impacts on the environment. At the same time, the nutrients and water present in manure management systems hold potential economic value as crop fertilizer and irrigation water. While technologies are available that allow for recovery and/or recycling of solids, nutrients and water, appropriate decision-support tools are needed to help farmers evaluate the practicality, costs, and benefits of implementing these systems on their unique farms.

What Did We Do?

In designing and refining the tool, we consider which economic components are important in driving the decision algorithm, as well as what is the most valuable economic output information for the user. We developed several “scenarios” defined by the unit processes used in the capture, treatment, storage, and usage of dairy manure. The costs and benefits related to each unit process were evaluated and aggregated for each scenario. Unit processes included flush/scrape activities, reception pit, sand recovery, solids separation, anaerobic digestion, composting, pond/lagoon storage, and tanker/drag hose land application.

Economic information was gathered from published literature, government documents, extension tools, and communication with academic, industry, and extension experts. We evaluated capital costs as an annual capital recovery value; operational costs including labor, energy, and repair and maintenance; cost savings resulting from sand/organic bedding and water reuse; fertilizer value of manure for use on-farm; revenue potential including the sale of treated manure nutrients and energy from anaerobic digestion; and the combined net costs or net benefits. Economic results are integrated into the multi-criteria decision algorithm. Results also elucidate economic tradeoffs across manure management systems (MMS), which can be used by farmers to assist in their decision-making.

What Have We Learned?

Economics is often about evaluating trade-offs between different choices or decisions. When evaluating results from the tool, we see that an increase in capital spending may lead to decreases in operational costs relative to capital costs, depending on farm size. This is due to a general reduction in labor and fuel costs associated with automated or additional manure treatment (e.g. increased spending on an MMS). For example, additional manure treatment can reduce land application expenses and increase cost savings from recovered sand or organic bedding. However, this larger capital outlay may or may not be possible based on the farm’s financial circumstances.

Future Plans

The next steps are to complete the economic analyses of a total of 60 MMS and integrate these into the decision-support tool. We plan to demonstrate this tool to extension specialists and producers to refine the user interface, key assumptions, functioning of the decision algorithm, and the usability of the results.

Authors

Erin E. Scott, PhD Graduate Assistant, University of Arkansas

Corresponding author email address

erins@uark.edu

Additional authors

Sudharsan Varma Vempalli, Postdoctoral Research Associate, University of Arkansas

Jacob Hickman, Program Coordinator, University of Arkansas

Jennie Popp, Professor, University of Arkansas

Richard Stowell, Professor, University of Nebraska-Lincoln

Teng Lim, Extension Professor, University of Missouri

Greg Thoma, Professor, University of Arkansas

Lauren Greenlee, Associate Professor, Penn State University

Additional Information

Related presentation during this session by Varma et al., titled “A Decision-Support Tool for The Design and Evaluation of Manure Management and Nutrient Reuse in Dairy and Swine Farm Facilities”.

Acknowledgements

We acknowledge funding support from the United States Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA) grant award (# 2018-68011-28691). We would also like to thank our full project team and outside experts for their guidance on this 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. 2022. Title of presentation. Waste to Worth. Oregon, OH. April 18-22, 2022. URL of this page. Accessed on: today’s date.

Whole farm assessment of nutrient extraction from dairy manure

Purpose

While animal manure contains nutrients and organic material that are beneficial for crop production, the concentrations of those nutrients are typically too low to allow economically viable transportation of bulk manures over long distances to where crops are sometimes produced. Therefore, dairy manure tends to be applied to soils near where it is generated. Since phosphorous (P) is conserved during manure handling compared to nitrogen, P concentrations in soils where dairy manure is applied tend to exceed crop demands. Due to the implication that P runoff from agricultural operations plays an important role in the eutrophication of streams and other water bodies, farmers are experiencing increasing pressure and regulation to not apply animal manures to fields that are already overloaded with P.

A possible solution to P overloading is to remove some of the P from manure before it is applied. In testing the MAnure PHosphorus EXtraction (MAPHEX) System Church et al. (2016, 2017, 2018), found that by treating liquid dairy manure with a screw press followed by a decanter centrifuge, 38 – 60% of the P could be removed from the manures of a wide variety of farms. A benefit to this approach is that the P removed, is concentrated into a stackable solid (about 72% moisture) that can be more economically transported to distant fields where P may be in deficit. The remaining liquid and course solids, containing greater than 90% of the manure N, can be beneficially used nearer the source without loading those soils with P. A comprehensive farm-scale evaluation of manure nutrient extraction is needed which can be done using the Integrated Farm System Model (IFSM; USDA, 2022). The IFSM has been used to assess other manure handling strategies along with many farm-scale options for crop, animal and feeding management.

What Did We Do?

We evaluated the whole-farm performance, environmental effects, and potential economic benefit of extracting P from dairy manure using a decanter centrifuge (Rotz et al., 2022). A farm in Pennsylvania with distant cropland was simulated with the IFSM to evaluate the feasibility of extracting P to reduce transport requirements on-farm or to produce a concentrated P product for off-farm use. Three production systems were evaluated with and without the use of centrifuge extraction. The first was the current farm with manure collected by flushing, next was the same farm with manure collection by scraping and the last was a modified farm with scraped manure where only forage crops were produced and concentrate feeds were purchased. Collection by scraping greatly reduced the volume of manure handled by the centrifuge thus reducing operating time and electricity use. Reducing the crop land and removing grain production created an imbalance in nutrient utilization with potential accumulation of P in the farm soil. Under this constraint, use of the centrifuge provided a method for removing a portion of the manure P for export from the farm.

Farm simulations estimated all forms of nitrogen, P, and carbon losses. This included erosion of sediment and runoff of sediment-bound and dissolved P across the farm boundaries. Costs for owning and operating the manure handling systems were determined using the economic component in IFSM. All equipment and facilities were amortized over an economic life and the annualized cost was added to other operating costs to get a total. Manure handling costs included fixed and operating (repair and maintenance, fuel, and labor) costs of the rotary screen, screw presses, and centrifuge. Manure hauling was also an important cost in the assessment because the number of trucks required and hauling distance varied among systems. Hauling cost included the amortized initial cost of trucks and annual costs for truck repair and maintenance, fuel, and operator labor.

What Have We Learned?

On a large dairy farm of 2,000 cows and 3,450 acres of land where manure must be transported to distant cropland to obtain uniform distribution, P extraction with a centrifuge provided a better ratio of nitrogen and P contents in manure used on nearby cropland and reduced transport costs for nutrients applied to more distant cropland. Centrifuge extraction was found to be more practical and economical when used with manure scraped from the barn floor than with flushed manure. Use of the centrifuge was not economically justified with the flush system where large volumes of low concentration liquid manure were handled. When barn floors were scraped, the benefit received through reduced manure volume more than offset the increased costs of owning and operating the centrifuge. To avoid long-term accumulation of soil P on the farm with less land (2,000 cows and 2,720 acres) where concentrate feed (27% of total feed) was imported, centrifuge extraction provided a material with a high P concentration that could be exported from the farm for other uses. Extracting the P in excess of crop needs cost about $1.14/lb P. This was generally greater than the price of phosphate fertilizer, but the extract also included other nutrients and micronutrients of value to crops.

A centrifuge provides a useful tool for extracting and concentrating manure P, but the economic benefit to the producer depends upon the value of the full array of nutrients contained, manure handling practices, and the end use of the extracted material. Although marketing this material for its P content alone may not be economical, the material may have other value and the reduction in long-term risk of surface water eutrophication has a less well-defined economic benefit to society.

Future Plans

The IFSM provides a tool for evaluating the performance, environmental impacts and economics of beef cattle and dairy production systems. The addition of the new component for modeling manure nutrient extraction technologies provides a tool for evaluating the whole farm costs and benefits of various technologies being developed or proposed for on-farm use. These can include manure processing based upon dissolved air floatation, evaporation, ultrafiltration, and the full MAPHEX system.

Authors

Alan Rotz, Agricultural Engineer, Agricultural Research Service, USDA

Corresponding author email address

al.rotz@usda.gov

Additional authors

Michael Reiner, Support Scientist, Agricultural Research Service, USDA; Sarah Fishel, Support Scientist, Agricultural Research Service, USDA; Clinton Church, Chemist, Agricultural Research Service, USDA

Additional Information

Church, C. D., Hristov, A., Bryant, R. B., Kleinman, P. J. A., & Fishel, S. K. 2016. A novel treatment system to remove phosphorus from liquid manure. Appl. Eng. Agric. 32: 103 – 112. doi:10.13031/aea.32.10999

Church, C. D., Hristov, A., Bryant, R. B., & Kleinman, P. J. A. 2017. Processes and treatment systems for treating high phosphorus containing fluids. US Patent 10,737958.

Church, C. D., Hristov, A. N., Kleinman, P. J. A., Fishel, S. K., Reiner, M. R., & Bryant, R. B. 2018. Versatility of the MAnure PHosphorus Extraction (MAPHEX) System in removing phosphorus, odor, microbes, and alkalinity from dairy manures: A four-farm case study. Appl. Eng. Agric. 34: 567 – 572. doi: 10.13031/aea12632

Rotz, C.A., Reiner, M., Fishel, S., & Church, C. 2022. Whole farm performance of centrifuge extraction of phosphorus from dairy manure. Appl. Eng. Agric. In press.

USDA-ARS. 2022. The Integrated Farm System Model, version 4.7. University Park, PA: USDA-ARS. Retrieved from https://www.ars.usda.gov/northeast-area/up-pa/pswmru/docs/integrated-farm-system-model

Acknowledgements  

This work was supported by the U.S. Department of Agriculture, Agricultural Research Service.  USDA is an equal opportunity provider and employer. The authors thank the producer who contributed characteristics of their farm for this assessment.

 

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.

Dairy Anaerobic Digestion Simulation Software

Purpose

Co-digestion of organic material with dairy manure represents an opportunity to provide both a revenue stream to anaerobic digester operations, through the collection of a tipping fee and/or increased biogas/electricity production, as well as a means for waste generators to dispose of their product in a beneficial way.

However, there are many factors for an operator to consider when deciding on whether to accept organic waste.  A major consideration is the volume of biogas that the material will generate when co-digested.  This can be used both to assign a value to the waste through increased biogas production and/or electricity sales, as well as to size equipment for producing, treating and potentially selling/using the biogas.   Estimating the biogas produced is a complicated process, encompassing many different factors of digester design, waste characteristics, and environmental factors.

To assist in this estimation, we have developed software that allows a user to predict the biogas production from mixed wastes and dairy manure based on changing herd sizes, as well as providing the ability to vary the timing and volume of addition of multiple organic wastes, throughout the course of a simulated year.  With this user-friendly tool, we hope to enable producers to better explore the opportunities that co-digestion offers.

What Did We Do?

The originally developed Cornell Anaerobic Digester Simulations software allowed the user to input a herd size and to select how much (if any) of seven wastes would be co-digested with the dairy manure.  This rudimentary method of simulation assumed that the same volume/mass would be applied to the digester in a steady-state constant fashion for the entire year that the simulations were run for.  However, that is unlikely to be the case in a real-world production environment.

In the new version of the software, we have incorporated the characteristics of over 200 wastes into a user selectable interface.  Once a waste type is selected, the user has the option to select when the waste is placed into the digester, whether that be on an everyday, weekly, monthly or custom basis with the option to select to which months of the year the additions occur.  When selecting a weekly or monthly basis, the user can select which day(s) of the week or month wastes are added, and in the custom basis, the user can select which days of the year additions occur.

Once the timing of addition is completed, the user can select how much of the waste is applied during each addition.  Whether that be a constant volume for each addition, or a custom volume for each addition.

The data for the specific wastes includes the dry matter and organic matter content as well as the biogas and methane yields.  Based on the type of waste we have also assigned a “digestibility” curve to the particular waste which when assuming a first order kinetic model of gas production, can provide the production of gas a function of time.  The production of biogas from all added wastes and the added manure is then summed for each day of the year to provide an estimate of the biogas production, on a daily basis, that can be summarized with a minimum/maximum/average on a monthly and annual basis.

What Have We Learned?

During the process of developing the software, we examined a few different techniques for estimating the timing of biogas production from co-digested wastes.  There are more complicated models available such as Anaerobic Digestion Model #1 (ADM1), however many more parameters must be known/estimated for each waste type, (not to mention requiring a much more complicated user interface).  We felt that using a simplified first order kinetic model provides a good way to add the necessary complexity to model biogas production over time without overly complicated calculations.  The simplification allowed us to include a more complicated and yet more real world means of modeling the addition of wastes to a digester that wouldn’t be possible with more complicated digestion/biogas production models.

Future Plans

Currently, the Cornell Dairy Anaerobic Digestion Simulation Software is capable of predicting the amount of heat necessary to maintain digester temperatures, as well as the parasitic electrical load.  Future additions will include modeling the energy usage (and effects on biogas) of treatment processes to produce Renewable Natural Gas (RNG) from biogas.

We would also like to include the ability to track nutrients through the process of digestion.  Nutrient additions from the co-digestion of wastes also represent an important consideration for farm as they may or may not have the land base/crop requirements to use all of the imported nutrients.  The cost of treatment of the effluent from the digester to remove nutrients, or the shipment of effluent off site may have to be added into the determination of how much of a “tipping fee” a farmer would need to charge for taking an organic waste for co-digestion.

We hope to make the program freely available to the public to use.  Currently, the software is written in MATLAB which ordinarily requires a license to operate, however it is possible to create an executable standalone program that can be shared and run without the need to purchase MATLAB.

Authors

Timothy Shelford, Extension Associate, School of Integrated Plant Science, Cornell University

Corresponding author email address

tjs47@cornell.edu

Additional authors

Curt Gooch, Senior Extension Associate Emeritus, Department of Biological and Environmental Engineering, Cornell University

Peter Wright, Agricultural Engineer, Department of Animal Science, Cornell University

Lauren Ray, Agricultural Energy Systems Engineer, Cornell University

 

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.

The MAnure PHosphorus EXtraction (MAPHEX) System for Removing Phosphorus, Odor, Microbes, and Alkalinity from Dairy and Swine Manures

Abstract

Animal manures contain nutrients [primarily nitrogen (N) and phosphorus (P)] and organic material that are beneficial to crops. Unfortunately, for economic and logistics reasons, liquid dairy and swine manure tends to be applied to soils near where it is generated. Over time, P concentrations in soils where dairy manure is applied builds up, often in excess of crop demands. We previously (Church et al., 2016, 2017) and have subsequently built, a full-scale version of a MAnure PHosphorus EXtraction (MAPHEX) System capable of removing greater than 90 percent of the P from manures. While originally designed to remove phosphorus, we have also shown that the MAPHEX System was also capable of removing odor and microbes, and of concentrating alkalinity into a solid, economically transported form. We have also lowered daily operating costs by testing the effect of lower-cost chemicals as alternatives to ferric sulfate, and by showing that the diatomaceous earth (DE) filtering material can be recycled and reused. We are currently building a system capable of treating over 100,000 gallons of Dairy Manure per day. This system is planned to be operational for demonstrating starting summer 2022.

Purpose

Swine and dairy manures are typically in slurry form and contain nutrients [primarily nitrogen (N) and phosphorus (P)] and organic material that are beneficial to crops. Unfortunately, the concentrations of nutrients in both manures are too low to make transportation of bulk manures over large distances economically viable. Furthermore, since it must be transported in tanks, that transportation is inconvenient as well. Therefore, these manures tend to be applied to soils near where they are generated, and, over time, P concentrations in soils increase to the point that soil P concentrations are often in excess of crop demands. Furthermore, because of the implication that P runoff from agricultural operations plays an important role in eutrophication of streams and other water bodies, farmers are experiencing increasing pressures and regulation to not apply animal manures to those soils.

We previously reported on an invention that 1) is designed to be a solution to the P overloading that happens when unnecessary P is added to agricultural soils, 2) is scalable such that it can be used as a mobile system, and 3) has shown to be capable of removing greater than 90 percent of the P from a wide range of dairy manures, while retaining greater than 90% of the N in the final effluent for beneficial use by the farmer.

What Did We Do?

We subsequently built a full-scale version of a MAnure PHosphorus EXtraction (MAPHEX) System capable of removing greater than 90 percent of the P from manures and have tested it on dairy manures. We also focused our efforts on lowering the daily operating costs of the system by developing a method to recover and reuse the diatomaceous earth used in the final filtration step, and testing alternative, lower cost chemicals that can be used in the chemical treatment step. We also performed pilot-scale tests on swine manures.

What Have We Learned?

The full-scale MAPHEX System removed greater than 90% of P from a wide variety of dairy manures, while leaving greater than 90% of the N in the final effluent to be used beneficially to fertigate crops. The System was also shown to recover and concentrate alkalinity into a solid form on a farm that used greater amounts of lime during manure handling, remove 50% of the odor from dairy manure and to remove greater than 80% of Total coliforms and E. Coli. Furthermore, the System has not shown to alter the pH of the final effluent respective to raw manures as other treatment technologies can. We have lowered daily operating costs by testing the effect of lower-cost chemicals as alternatives to ferric sulfate, and by showing that the diatomaceous earth (DE) filtering material can be recycled and reused.

In pilot-scale swine testing, we found that the MAPHEX System can remove greater than 96% of the phosphorus in swine manures. This essentially P free effluent can be beneficially used for fertigation without further loading the receiving soils with P. Scaling up the pilot-scale testing has the potential to reduce swine manure storage volumes to allow for mitigation of overflow problems during large storms. Furthermore, the pilot-scale study suggests that capital equipment costs and treatment costs for swine manure would be lower than for treating dairy manure.

Future Plans

We are currently building a simplified version of the MAPHEX System that will be capable of treating over 100,000 gallons of dairy manure per day. This system is planned to be operational for demonstrating starting summer 2022. We plan to use this simplified version for demonstration tests, and use the results obtained to model the effects of using MAPHEX technology compared to conventional manure handling practices on two paired watersheds. We also plan to demonstrate the full-scale system on a wide range of swine manures with on-farm testing.

Author

Clinton D. Church, Research Chemist, USDA-ARS University Park, PA

Corresponding author email address

Cdchurch.h2o@netzero.com

Additional Information

Church, C. D., Hristov, A. N., Bryant, R. B., Kleinman, P. J. A., & Fishel, S. K. (2016). A novel treatment system to remove phosphorus from liquid manure. Applied Engineering in Agriculture, 32: 103 – 112. doi:10.13031/aea.32.10999

Church, C. D., Hristov, A. N., Bryant, R. B., & Kleinman, P. J. A. (2017). Processes and treatment systems for treating high phosphorus containing fluids. US Patent 9,790.110B2.

Church, C. D., Hristov, A. N., Kleinman, P. J. A., Fishel, S. K., Reiner, M. R., & Bryant, R. B. (2018). Versatility of the MAPHEX System in removing phosphorus, odor, microbes, and alkalinity from dairy manures: A four-farm case study. Applied Engineering in Agriculture, 34: 567 – 572. doi:10.13031/aea12632

Church, C. D., Hristov, A., Bryant, R. B., & Kleinman, P. J. A. (2019). Methods for Rejuvenation and Recovery of Filtration Media. USDA Docket Number 129.17. U.S. Patent Application Serial No. 62/548,23

Church, C. D., S. K. Fishel, M. R. Reiner, P. J. A. Kleinman, A. N. Hristov, and R. B. Bryant. 2020. Pilot scale investigation of phosphorus removal from swine manure by the MAnure PHosphorus Extraction (MAPHEX) System. Applied Engineering in Agriculture 36(4): 525–531. doi: 10.13031/aea13698

https://www.ars.usda.gov/people-locations/person/?person-id=40912

https://tellus.ars.usda.gov/stories/articles/mining-manure-for-phosphorus/

https://agresearchmag.ars.usda.gov/2016/dec/phosphorus/

https://jofnm.com/article-112-Packaging-phosphorus-for-the-future.html

https://lpelc.org/versatility-of-the-manure-phosphorus-extraction-maphex-system-in-removing-phosphorus-odor-microbes-and-alkalinity-from-dairy-manures/

 

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.

Does Irrigation of Liquid Animal Manure Increase Ammonia Loss?

Purpose

Large bore traveling gun and center pivot irrigation systems have been used to apply treated lagoon effluent, liquid animal manure, and untreated slurry from swine and dairy farms in many parts of the USA. The primary advantage of using irrigation equipment to spread manure on cropland are the lower costs for energy and labor, and the higher speed of application as compared to using a tractor-drawn spreader. The primary disadvantages are related to increases in odor release and the possibility of spraying manure on roads or another person’s property.

Ammonia-N loss from land application of manure is important because it is a loss of fertilizer nitrogen, and it is a source of air pollution. A previous study and several extension publications state that irrigation of animal manure increases ammonia-N loss by 10% to 25% (Chastain, 2019). As a result, the total ammonia-N loss was the sum of the ammonia-N lost while the manure traveled from the irrigation nozzle to the ground and the ammonia-N lost as the manure released ammonia-N after striking the ground.

The objective of this presentation is to summarize the results of a meta-analysis of 55 data sets from 3 independent sources to quantify the ammonia-N lost during the interval of time from when the liquid manure exited the irrigation equipment and when a sample was collected on the ground. The complete review, data analysis, and the data used were provided by Chastain (2019).

What Did We Do?

The study included data from traveling gun, center pivot, and impact sprinkler irrigation of untreated liquid and slurry manure, lagoon supernatant, and effluent from an oxidation ditch. The data sets included measurements of the total solids content (TS, %), total ammoniacal N concentration (TAN = ammonium-N + Ammonia-N), and total nitrogen (TKN) for a sample collected from the lagoon or storage to describe what was in the manure that left the irrigation nozzle and measurements of the TS, TAN and TKN in the samples that were collected from containers on the ground. The concentrations of TS, TAN, and TKN in the ground collected manure samples were plotted against the TS, TAN, and TKN concentrations in the irrigated manure. The data pairs were analyzed using linear regression to determine if there was a statistically significant difference between the irrigated and ground collected samples. If there was perfect agreement the slope of the line would be 1.0. Therefore, statistical tests were used to determine if the slope of the line was statistically different from 1.0. If the test indicated that the slope was not significantly different from 1.0 then irrigation did not change the concentration of the TS, TAN, or TKN.

What Have We Learned?

Well-known data used in irrigation design indicates that evaporation loss during irrigation ranges from 1% to 3.5%. The plot of the data for irrigated manure is shown in Figure 1. It was determined that the slope of the regression line was statistically greater than 1.0. Therefore, evaporation losses were small, 2.4%, and agreed with previous studies on irrigation performance.

Figure 1. Comparison of the total solids content of the irrigated manure and the samples collected on the ground indicated that evaporation losses were 2.4%.

The plot of the TAN concentrations collected on the ground and the TAN contained in the irrigated water is shown in Figure 2.). The results showed that irrigation of manure did not result in a change in the concentration of TAN. Therefore, irrigation of manure did not cause ammonia-N loss.

The same type of analysis was done for the total nitrogen data to serve as check on the TAN results. As expected, the analysis showed that irrigation did not significantly alter the concentration of TKN.

Figure 2. The concentration of the total ammoniacal nitrogen was not changed as the manure traveled through the air. This was indicated by a regression line slope that was not significantly different from 1.0.

A previous study reported TAN losses ranging from 10% to 25% during irrigation of liquid manure. Error analysis of the techniques used in these studies indicated that most of the average ammonia-N loss predicted was due to volume collection error in the irrigate-catch technique that was used, and not evaporation and drift as was assumed (see Chastain, 2019). It was concluded that irrigation, as a manure application method, did not increase ammonia-N losses. These results do not imply that ammonia volatilization after manure strikes the ground is to be ignored. The suitability of irrigation as a liquid manure application method should be evaluated based on the level of treatment and the potential impact of odors on neighbors.

Future Plans

These results are being used in extension programs and to help refine estimates of ammonia-N loss associated with land application of manure.

Author

John P. Chastain, Professor and Extension Agricultural Engineer, Agricultural Sciences Department, Clemson University

Corresponding author email address

jchstn@clemson.edu

Additional Information

Chastain, J.P. 2019. Ammonia Volatilization Losses during Irrigation of Liquid Animal Manure. Sustainability 11(21), 6168; https://doi.org/10.3390/su11216168.

 

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.

Impact of Sludge on Nutrient Concentration in Anaerobic Swine Lagoon Supernatant

Purpose

The most common waste management practice on hog farms in Eastern North Carolina are anaerobic lagoons. Lagoons contain three zones: [1] sludge storage zone at the bottom, [2] treatment zone for incoming manure in near the middle, and [3] a liquid (supernatant) storage zone at the top. The supernatant is land applied throughout the year as a nutrient source for growing crops on farms while the middle (treatment) zone is required to remain full to ensure effective treatment.

Considering the risk that hurricanes pose to North Carolina and the hog sector (particularly during late summer months), close lagoon management is critical to avoid risk of overflow or breach. Currently, regulations allow swine growers to lower the effluent level in their lagoons by applying part of the treatment zone effluent. Conditional to this allowance, however, is that the treatment zone contains at least 4-feet of depth that is sludge-free. This condition aims to ensure applied effluent is safe for application.

While this condition is helpful to reducing the risk of applying higher concentration of phosphorus, zinc, and copper to crops, many producers do not meet this condition due to excessive sludge buildup and would not be able to lower the lagoon level which poses a significant risk during intense rainfall events.

This study aims to quantify the impact of the sludge-free depth in the lagoon on the quality of supernatant during the drawdown period. Findings will help with precision nutrient application from swine manure and allow for further drawdown during necessary storm events.

What Did We Do

This study used a dataset representing 27 swine operations in Eastern North Carolina between 2016-2021. The dataset includes:
1. Monthly effluent/waste sampling analysis,
2. Annual sludge surveys, as well as
3. Lagoon level readings.

This dataset was analyzed using statistical methods to quantify the impact of seasonality (time of year), farm type (sow, finisher, or farrowing), and sludge level on nutrient concentration in the effluent.

Most growers use depth, in inches, to report volumes applied or available for storage. However, when comparing lagoons with different designs, this can be a challenge. As such, we developed two parameters to facilitate cross-farm, cross-lagoon comparisons. The first is “freeboard ratio” (FBR), which refers to the relative “fullness” of the storage zone in the lagoon. FBR value between 0 and 1 indicates the lagoon is currently within the storage volume (between start and stop pumps), values greater than 1 indicate the lagoon is in drawdown, and negative values indicate the lagoon level exceeded the storage volume and is currently in the rainfall/storm storage zone and must be lowered promptly. The equation used to calculate FBR is as follows:

TBR= LFB-Lstart , variables defined in Figure 2.
Lstop-Lstart

The second variable is “sludge level ratio” (SLR), which refers to the relative treatment volume available compared to the 50% treatment volume required. SLR values greater than 1 indicate that more than 50% of the treatment volume is sludge-free in the lagoon and therefore drawdown can proceed, and no sludge removal is necessary. SLR values less than 1 indicate that less than 50% of the treatment volume is available and drawdown might not be feasible. The equation used to calculate SLR is as follows:

SLR= Lsludge-Lstop , variables defined in Figure 2.
L0.5. Trt-Lstop
Figure 2. Anaerobic lagoon zones used to calculate study parameters FBR and SLR

What Have We Learned

In analyzing the dataset we observed that only 2% of the samples were collected while the lagoon level exceeded storage level (above the start-pump level). This suggests the majority of studied operations were successful in managing effluent despite the wet years observed between 2016 and 2021. By comparison, 22% of the samples were collected while the lagoon was at a draw-down state (the entire storage volume is empty and the treatment zone is partially emptied).

Additionally, 38% of the samples collected were associated with lagoons that needed sludge removal (SLR < 1). These results are summarized in Table 1, with 12% of samples collected from lagoons in drawdown (FBR > 1) and in need of sludge removal (SLR < 1). This latter group of samples represent the primary concern for lagoon drawdown.

 

Table 1. Summary of FBR and SLR Interactions
Lagoon Sample Class Sludge Level Ratio (SLR)
No Removal Removal Due
Freeboard Ratio (FBR) Above stop-pump 40% 26%
In drawdown 22% 12%

The season was a significant predictor of the lagoon level (p < 0.001), with the late irrigation season (July – Sept) showing the least effluent volume in the lagoon. On average, 91% of the storage volume was unoccupied. This compares to the winter months (Oct – Feb) and the early irrigation season (Mar – June) with 81 and 69% of the storage volume empty, respectively.

For all seasons the mean ratio of N : P2O5 : K2O in the supernatant is 4 : 1 : 8.2. There was less variability for N and K content with the lagoon level than for P, Zn, and Cu. This can be attributed to the N and K being primarily in soluble forms in the lagoon supernatant compared to P2O5, Zn and Cu which are mostly bound to solids.

The analysis showed a greater variability in Zn, Cu, and P levels with changes in solid concentration in the supernatant as well as the amount of suspended solids as a result of wind or active lagoon agitation/sludge removal.

Overall, the results showed lagoon drawdown and existing sludge reserves to have a combined effect on nutrient concentrations in the supernatant, particularly for phosphorus.

Future Plans

This study will inform ongoing research to predict temporal variability in nutrient content in the lagoon due to weather, operational decisions, and time of year. Near term, these observations will help guide application rates to ensure P levels meet crop demands particularly during late-season drawdown without significantly increasing soil P levels. In addition, this work will be part of a larger study to predict the performance of anaerobic treatment lagoons under future climate conditions.

Authors

Presenting Author:
Carly Graves, Graduate Research Assistant, North Carolina State University

Corresponding Author:
Dr. Mahmoud Sharara, Assistant Professor & Waste Management Extension Specialist, North Carolina State University
msharar@ncsu.edu

Acknowledgements

Thank you to Smithfield Foods, Inc. for funding this research and providing datasets of sludge surveys.

Videos, Slideshows and Other Media

https://content.ces.ncsu.edu/sludge-sampling-in-anaerobic-treatment-swine-lagoons

 

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.

Overview of ODA’s Division of Livestock Environmental Permitting

Purpose

The purpose of this presentation is to provide a complete overview of ODA’s Division of Livestock Environmental Permitting (“ODA-DLEP”). ODA-DLEP regulates any livestock facility in Ohio that has the following number of animals or greater:

    • 700 mature dairy cows
    • 1,000 beef cattle or dairy heifers
    • 2,500 swine weighing more than 55 pounds
    • 10,000 swine weighing less than 55 pounds
    • 82,000 layers
    • 125,000 broilers or pullets
    • 500 horses
    • 55,000 turkeys

What Did We Do

Ohio Department of Agriculture’s Division of Livestock Environmental Permitting (“ODA-DLEP”) regulates the siting, construction, and operation of Ohio’s largest livestock facilities, referred to as Concentrated Animal Feeding Facilities (“CAFF”). ODA-DLEP’s primary objective is to minimize any water quality impacts, including both surface and ground waters, associated with the construction of new or expanding CAFFs, as well as implementation of best management practices once a CAFF becomes operational. These best management practices include management of manure, insect and rodent control, mortality management, and emergency response practices. ODA-DLEP issues Permits to Install (for construction) and Permits to Operate (for operations).

In addition, ODA-DLEP conducts routine inspections of each CAFF at least once a year, responds to complaints, and participates in emergency response. Inspections are conducted to review a CAFF’s compliance with Ohio Revised Code 903 and Ohio Administrative Code 901:10, the laws and regulations governing Concentrated Animal Feeding Facilities.

Finally, ODA-DLEP administers the Certified Livestock Manager program. Any individual in the State of Ohio that manages 4,500 dry tons of solid manure or 25 million gallons of liquid manure is required to be a Certified Livestock Manager (“CLM”).

What Have We Learned

Livestock operations continue to get larger and more concentrated and as a result, regulations are necessary to ensure proper handling and management of manure, particularly with land application of manure.

Future Plans

Over the past several years, DLEP has started to see more interest in manure treatment technologies. This could include, but is not limited to, anaerobic digestion, nutrient recovery, solids separation, and wastewater treatment. Technologies like this could greatly alter the landscape of the livestock industry by fundamentally changing the way manure is handled and how nutrients from manure are applied. DLEP does have regulations in place to account for manure treatment technologies. However, regulations, and specifically changes to regulations, cannot maintain the same pace as these technological advancements.

Authors

Samuel Mullins, Chief of ODA-Division Livestock Environmental Permitting
Samuel.mullins@agri.ohio.gov

Additional Information

https://agri.ohio.gov/divisions/livestock-environmental-permitting
https://codes.ohio.gov/ohio-administrative-code/901:10
https://codes.ohio.gov/ohio-revised-code/chapter-903

Videos, Slideshows and Other Media

ODA Division Spotlights – Division of Livestock Environmental Permitting 1

ODA Division Spotlights – Division of Livestock Environmental Permitting 2

 

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.

Quantification of greenhouse gas emission reductions for eight dairy manure management systems employed in the Northeast and upper Midwest

Purpose

Dairy farmers and their key advisors, the balance of the dairy value chain, policy makers, government officials, non-governmental organizations (NGOs), and astute consumers value best available information about the greenhouse gas (GHG) emissions associated with milk production. In 2020, the Innovation Center for US Dairy set three 2050 environmental stewardship goals spanning from cradle to processor gate, including GHG neutrality. Further, they committed to reporting on progress towards the goals every five years starting in 2025.

Dairy farming economics will continue to drive production consolidation, a trend that substantially began in the 1960s. Consolidation results in fewer total farms yet only somewhat fewer total cows overall; thus, the number of cows per farm has substantially increased. The best management practice of long-term manure storage (LTS) was developed by USDA NRCS decades ago to protect water quality due to manure runoff and infiltration. The number of farms with LTS increased as the number of cows per farm increases. Overall, LTSs are largely anaerobic, resulting in the emission of methane (CH4) and in some cases nitrous oxide (N2O). It is generally understood that the 2nd largest cradle to farm gate CH4 emission source is LTS. Continued industry consolidation will result in more LTS over time.

Continued use of (LTS) to protect water quality, coupled with today’s use of manure treatment practices on-farm and the US dairy and other GHG reduction goals set are important reasons to quantify manure-based GHG emissions.

What Did We Do

To help dairy farmers and others understand the relative impact manure management (MM) has on GHG emissions, seven integrated MM systems that are utilized by farmers in the Northeast/upper Midwest were analyzed. The approach was to calculate the GHG emission impacts using best available information and procedures. The seven systems analyzed, each shown in process flow order, were:
1. Long-term storage (LTS)
2. Solid-liquid separation (SLS), LTS
3. SLS, LTS with cover/flare (CF)
4. Anaerobic digestion (AD) of manure only, SLS, LTS
5. AD, SLS, LTS with CF
6. AD of manure/food waste, SLS, LTS with CF
7. AD of manure/food waste, SLS, LTS with cover/gas utilization

The resulting net GHG emission values were compared to the baseline MM practice of daily spreading.

Impact of systems on GHG emissions associated with LTS and offsets from net energy production and landfill organics diversion (anaerobic digestion systems only) were included. Results were normalized on a metric ton of carbon dioxide equivalent (CO2e) per cow-year basis. A 100-year global warming potential (GWP100) value of 25 and a 20-year GWP20 (84) were used for comparative purposes in calculating CO2e. A sensitivity analysis was conducted to understand the impact of volatile solid (VS) biodegradability on GHG emissions and anaerobic digester system biogas leakage.

What Have We Learned

Not surprisingly, results show that the largest GHG reduction opportunity was from anaerobic co-digestion of dairy manure with community substrate (7. above). The net GHG emission from this system was -16 (GWP100) and -43 (GWP20) metric tons CO2e per cow-year (GHG avoidance). This is compared to the GHG emission of 1.9 (GWP100) and 5.6 (GWP20) metric tons CO2e per cow-year from the LTS (1. above). Sensitivity analysis results showed manure VS degradability had meaningful impact on GHG emissions, particularly for Scenario 4, and for the co-digestion scenarios, the most significant impact – 5% – resulted in a leakage increased from 1% to 3%. While using SLS with an impermeable cover and flare system on a separated liquid manure LTS reduces CH4 emissions as compared to uncovered long-term liquid manure storage, the practice does not provide an opportunity to achieve net zero or better manure enterprise GHG footprint because the energy in the biomass is wasted and diversion of organics from landfills cannot be effectively included.

Future Plans

Next step is to develop additional results for integrated MM systems that included advanced manure treatment technologies that further reduce the organic loading on LTSs. Further parallel work will focus on quantifying these same advanced manure treatment technologies on their partitioning of digester effluent nutrients for off-farm export.

Authors

Curt A. Gooch, Sustainable Dairy Product Owner, Land O’Lakes – Truterra
cgooch@landolakes.com

Additional Authors
-Peter E. Wright, Extension Associate, Cornell PRO-DAIRY Dairy Environmental Systems Program
-Lauren Ray, Extension Support Specialist III, Cornell PRO-DAIRY Dairy Environmental Systems Program

Additional Information

More information on related work can be found on the Cornell University PRO-DAIRY Dairy Environmental Systems Program website: https://cals.cornell.edu/pro-dairy/our-expertise/environmental-systems.

Acknowledgements

The Coalition for Renewable Natural Gas and the New York State Department of Agriculture and Markets provided financial resources to support this work.

 

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.

Experience of Removing and Land Application of Lagoon Solids

Purpose

Manure lagoon systems are designed to hold and treat animal farm wastewater for a predetermined period and remain popular in many livestock farms. If the lagoon is properly designed and built, many years can go by without any significant maintenance requirements outside of water management, pumps and valves. Depending on the capacity and maintenance, additional manure solid removal is often required to reduce the amount of manure solids entering the lagoon storage. When excessive solids build-up or sludge was found, significant odor and low quality/quantity of flushing water would be the issues.

This study documents experience to prepare for and complete land application of lagoon effluent with heavy solids from a flush dairy lagoon in central Missouri. The free stall barn uses mattress bedding with supplemental cedar shavings and houses 140-160 lactating cows. Preparation included measuring lagoon sludge depth and lab analysis of sludge characteristics and scouting for crop fields for land application prior to contacting contractors for a bidding process. A contractor team utilized specialized equipment to dilute, agitate, pump and land apply approximately 8 million gallons of diluted lagoon solids in less than nine working days. Lagoon effluent was sampled throughout the process to monitor the mass of nutrients applied to specific plots of land. For effective lagoon solids removal and land application, proper preparation, specialty equipment and trained professional, timing of the crop fields, and adequate field working days are critical. Simple, non-mechanical technologies are available for even small to midsize dairy farms to reduce the cost of lagoon maintenance by preventing the bulk of solids from entering the lagoon.

What Did We Do?

We documented the process of lagoon solids removal for land application, considering the preparation (sludge and effluent sampling), specialty equipment and trained professionals, timing of the crop fields, and adequate field working days. The barn was flushed two to three times per day, with three times per day being typical. There was, at one time, an elevated screen that helped remove the large solids from the flush, but the screen system fell into disrepair several years ago and was abandoned. Solids in the lagoon were agitated and pumped out from May 21, 2020, through June 8, 2020, Figures 1 and 2. A total of 8 million gallons over 280 acres was applied to fields further away from the lagoon, including neighbor’s crop fields that were 1.5 miles away. Equipment needs and specifications were documented (Canter et al., 2021) and being prepared for an Extension publication.

Figure 1. PTO-drive lagoon agitators and agitation boat in operation.
Figure 2.  A dilution pump was used to pump water from the nearby lake (left) to the dairy lagoon (right) with agitation boat and lagoon agitation working in the background.

Daily lagoon effluent samples were taken multiple samples throughout the day on June 2 to gauge the consistency of nutrient concentrations. Results suggest that once completely mixed via agitation, the applied nutrient concentration from a single sample is a reliable estimate within a working day if the moisture content is consistent. The initial slurry had a 10-13 percent solids content, so a significant amount of dilution water was needed to dilute the solids content to the target range. The exact amount of dilution water used was unknown. Figure 3 shows the concentration and moisture data. In general, the higher the moisture content (less solids) in the slurry samples, the higher the concentrations of the important manure nutrients are. The team evaluated potential technologies based on historical experience and first-person interviews. A pull-plug sediment basin (PPSB) was selected after reviewing cost and visiting with a farmer who operated a PPSB and was satisfied with the overall operation and performance (Canter et al., 2021). The application rate of important manure nutrients did show variation during the several days of land application, suggesting an improvement to the real-time effluent nutrient measurement and land application rate adjustment could be improved to provide more consistent nutrients to the crop fields.

Figure 3. Concentrations and moisture content of slurry samples from the lagoon.

What Have We Learned?

Manure management can be a burden for animal feeding operations, which can potentially become a significant threat to the profitability and management of farms if not proactively managed. Owners would be well-advised to survey their lagoon yearly to track solid inventory and plan ahead for the amount of land needed for solids application. Proper solids removal from the lagoon, particularly if regular and effective solids removal has been neglected, requires specialized equipment to reduce liquid supernatant on an annual or semiannual basis. There can be significant variability of nutrient concentration and resulting mass applied. Testing for nutrient concentrations in the lagoon, whether supernatant or sludge, or both, can be misleading due to variance in concentrations due to moisture content as the applicators dilute and concentrate the solids during the land application process.

Daily sampling during land application could help but may not be practical due to the analysis time generally required by labs (5-10 business days). Sensors and probes are available that return instantaneous values and have been used in municipal and industrial wastewater treatment for over a decade. Companies have offered integrated sensors for land application equipment, combining them with their GPS and flow control system to give a complete and accurate summary of nutrient application. Simple, non-mechanical technologies are available for even small to midsize dairy farms to reduce the cost of lagoon maintenance by preventing the bulk of non-degradable solids from entering the lagoon. Implementation of a coarse solids separation system such as the PPSB could significantly reduce the long-term cost of manure management by allowing the operator to use more common equipment (e.g., a loader and spreader) to remove solids from the manure management system.

Future Plans

Continuous monitoring of the lagoon sludge level at a minimum of annual basis is needed to closely monitor the lagoon solid accumulation and performance of the PPSB. The authors are collaborating with NRCS team to improve the PPSB and ways to monitor the lagoon sludge level.

Authors

Teng Lim, Extension Professor, Agricultural Systems Technology, University of Missouri

Corresponding author email address

Limt@missouri.edu

Additional authors

Timothy Canter, Extension Specialist, Agricultural Systems Technology, University of Missouri

Joseph Zulovich, Extension Assistant Professor, Agricultural Systems Technology, University of Missouri

Additional Information

    1. Canter, T., Lim, T.-T., and J. A. Zulovich. 2021. Field Experience of Removing and Land Application of Dairy Lagoon Solids. In International Symposium on Animal Environment and Welfare. Rongchang, Chongqing, China.
    2. Lim, T.-T. 2022. Lagoon Solids Removal, Lessons Learned. Cleanout for Lagoons and Anaerobic Digesters, Jan 21, 2022. Webinar of Livestock and Poultry Environmental Learning Community (LPELC). https://lpelc.org/cleanout-for-lagoons-and-anaerobic-digesters/
    3. Canter, T., Lim, T.-T., Chockley, T. 2021. Considerations of Pull-Plug Sedimentation Basin for Dairy Manure Management. University of Missouri Extension Publication. Retrieved September 25, 2021. https://extension.missouri.edu/publications/eq302.

Acknowledgements

USDA NIFA, Water for Food Production Systems Program A9101, for supporting the project. It is titled “Management of Nutrients for Reuse”, a multi-faceted project that involves professionals from the University of Arkansas, University of Nebraska, Colorado School of Mines and Metallurgy, Case Western University, and University of Missouri.

Joe Harrison, Professor, Livestock Nutrient Management program, Washington State University

Gilbert Miito, Postdoctoral Fellow, Agricultural Systems Technology, University of Missouri

Richard Stowell, Biological Systems Engineering, University of Nebraska

Farm crew and custom applicator team for their help.