Manure management is a major system on dairy farms, and there is a goal to minimize costs and maximize benefits. Technology that would reduce the mass of the manure to be spread, produce energy and a potential by-product for off-farm sales is needed. Adding wet gasification technology to existing manure systems with the goals of reduced spreading costs and possibly increased by-product sales was evaluated on a central New York farm that was considering expanding. For expansion to be possible, additional cropland was needed to recycle the additional manure at a further distance from the farmstead. An economic analysis examining the potential impact the wet gasification technology would have on the farm was conducted and results were shared with the dairy producer for use in making informed decisions.
What did we do?
A wet gasification technology that was presented by the manufacturer to be able to extract energy from manure solids (also reducing mass) was evaluated to determine the potential as an improvement to the farm’s existing manure management system. Application of this technology on an example farm was investigated to see what the applications might be on the existing farm (1,500 cows and 1,590 acres) and when expanded to 2,500 cows with 2,990 acres of cropland. Current and projected farm data along with cost and performance data from the manufacturer of the gasification system were used to perform an annual economic cost-benefit analysis as a way to determine the value of the system to the farm’s manure management enterprise.
Figure 1. Example Mass and Energy Flows for a Wet Gasification System
What have we learned?
There are many variables to consider, and the results of the sensitivity analysis show that the variables that influence the outcome of the total annual economic cost-benefit analysis are the ones least under the control of the technology provider or farm (capital cost, lost capital rate, milk production change due to bedding use change, nitrogen value of fertilizer, price of electricity, and value of the ash). Annual spreading costs at the time of analysis ranged from $36/acre for close fields with a low amount of manure spread, to $256/acre for further fields spread at a high amount of manure.
For the case farm analyzed, the system economics would only be favorable if optimistic values were assumed for some of the predictor variables such as high prices for the ash by-product and/or higher prices for the excess energy produced. Raw dairy manure’s moisture content is too high for efficient gasification. Wet gasification is better suited to operations where the raw manure has lower moisture content (due to substantial bedding use) or can be pre-processed to obtain a very dilute liquid stream (that can be spray irrigated) and a solid product, having 25-30% solids, that could be processed by gasification to produce a salable ash. The values for byproducts, energy and nutrients from manure, need to be large enough to support a manure treatment system. Dairy farms need to consider the impact of a manure treatment technology on the whole farm system.
Prices to obtain a zero economic benefit (net benefits minus costs equal $0) for the expanded 2,500-cow dairy in central NY for each variable alone.
Variable
Break-Even Price
Comments
Capital costs ($/Unit)
$0 Wet Gasification
$0 for SLS
$1,750/kW for steam gen set
Assuming grants are available
Assuming a separator already exists
Steam gen-set is $1,750/kW
Electric Price ($/kWh)
$0.156/kWh
5M kWh/yr. produced
Includes $0.03/kWh maintenance cost on engine generators. (This is renewable energy but only ~50% reduction in GHG
Hauling cost ($/load)
$2,530/load
159 loads/yr. reduced
8,400 gallons/load (approximately a 420-mile round trip)
Ash Sales ($/ton)
$374/ton
898 tons/yr. produced
This price includes the reduced hauling costs as the water separated from the ash can be spray irrigated without hauling.
Future Plans
We continue to evaluate manure treatment systems that have the potential to reduce the mass of the manure to be spread, produce energy, partition the nutrients, reduce greenhouse gas emissions, and a produce a potential by-product for off-farm sales and extending this knowledge to dairy operators.
Corresponding author, title, and affiliation
Peter Wright, Agricultural Engineer, Dept. of Animal Science, Cornell University
Pew2@cornell.edu
Other authors
Curt Gooch, Senior Extension Associate at Cornell University, Dept. of Animal Science, PRO-DAIRY
Additional information
Additional project information can be found on the dairy environmental system webpage: www.manuremanagement.cornell.edu.
Acknowledgements
The farm and the wet gasification technology company provided the needed data to make the economic analysis. Funding for this project was supported by Cornell’s Jumpstart program.
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.
This study has the objectives of characterizing dairy manure pre and post solid-liquid separation (SLS), estimating and comparing processing efficiencies between different technologies, and relating emissions to manure characteristics by using modeling tools.
What did we do?
Manure samples from nine dairy farms in southern and eastern Wisconsin were collected every two weeks. All nine farms separated manure into liquid and solid streams and seven farms used anaerobic digesters (ADs) prior to solids separation (Table 1). For all farms, manure was sampled pre-processing (untreated manure) and after any individual processing step in order to isolate the performance of each treatment unit at each farm (Figure 1). All manure samples were analyzed for total solids (TS), volatile solids (VS), total nitrogen (TN), ammonia (NH3), total phosphorus (TP), total potassium (TK) and chemical oxygen demand (COD). Separation efficiency was estimated by solving a system of two equations of separation mass balance (Equations 1 and 2) based on the concentrations of each constituent.
Where:
X (kg) is the constituent under evaluation (e.g. TS, NH3, etc.)
[ ] indicates percent concentration in the solid (solid, out), liquid (liquid, out) fractions after separation, and total before separation (total, in)
Manure (kg) is the manure mass in the solid (solid, out), liquid (liquid, out) fractions after separation, and total before separation (total, in)
What have we learned?
Both screw press and centrifuge technologies achieve higher separation efficiencies for TS and VS than for TN, NH3, TP, and TK, meaning that more TS and VS stay with the solids fraction. Moreover, NH3stays almost entirely in the liquid fraction. Results indicate that centrifugation might achieve higher TP separation efficiencies than screw pressing. Greenhouse gas (GHG) emissions, were affected by the management practices used to handle the liquid and solid fractions. Methane emissions from liquid storage are reduced as a percentage of the VS stays with the solids fraction. However, nitrous oxide emissions from the separated solids might increase if separated solids are stored and not quickly land applied or transported outside of the farm for posterior use.
Future Plans
Analysis for anaerobic digestion efficiency and pathogen inactivation will be incorporated in this study to conduct a complete assessment of manure characteristics after AD and SLS and their impact on different environmental indicators.
Table 1. Summary of each farm’s manure management process.
Farm ID
AD
SLS
Feedstock
1
Mixed plug flow
Screw press
Dairy manure
2
No
ABRU
Dairy manure
3
Complete Mix
Screw press with blower
Dairy manure
4
Mixed plug flow
Screw press
Dairy manure
5
Mixed plug flow
Screw press
Paunch manure, food waste
6
Mixed plug flow
Screw press
Dairy manure
7
Mixed plug flow
Screw press
Dairy manure
8
Complete Mix
Centrifuge
Dairy manure, ethanol byproduct, FOG
9
No
ABRU
Dairy manure
AD: anaerobic digestion, SLS: solid-liquid separation, ABRU: aerobic bedding recovery unit , FOG: fat, oil, and grease
Figure 1. Scheme of the manure processing technologies and sampling locations.
Authors
Aguirre-Villegas Horacio Andres. Assistant Scientist. Department of Biological Systems Engineering, University of Wisconsin-Madison. aguirreville@wisc.edu
Sharara Mahmoud. Assistant Professor. Department of Biological and Agricultural Engineering. NC State University
Larson Rebecca. Associate Professor. Department of Biological Systems Engineering, University of Wisconsin-Madison
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.
Aerobic treatment has potential to be more practical for any size operation, reduce odors, reduce risk of runoff by facilitating application to growing crops, and reduce energy use when distributing manure nutrients.
Farm-based aeration, created through an upward/outward surface flow, was first introduced in the 1970’s and brought partial success. With significant performance issues, challenges with struvite within manure recycling pipes/pumps, and the growing trend to store manure within pits under barns, further research with manure aeration was largely abandoned. Very little research has been done on aerobic treatment within manure storage systems since traditional aeration using air blowers has been considered too expensive. Previous research sought to mimic traditional domestic wastewater treatment systems which also purposely perform denitrification. Not always a goal for farm operations in years past, retaining Nitrogen within wastes used as fertilizer is now usually a goal. Thus, past aerobic treatment systems were not designed to fully benefit today’s modern farms.
In 2006, hog producers were introduced to an updated version of equipment providing Widespreading Induced Surface Exchange (WISE) aeration, specifically for reducing hog manure odor while irrigating lagoon effluent. The results became a “wonder” for the site’s CAFO permit engineer. Documentation showed that significant aeration was occurring at a rate much higher than could occur with the energy input used by traditional bubble blowers. This indicated that aeration of manure ponds and lagoons may not be too expensive after all. More questions led to a USDA NRCS-supported study, which revealed much more information and brought out more questions. The final report of that study is available at http://pondlift.com/more-info/, along with other information on the technologies described.
The NRCS-funded study revealed the basis for previous performance failures, while it also showed the basis for getting positive aeration performance at liquid manure storage sites: Ultimately, this information showed that large reductions of manure odor can be obtained while offering a new paradigm for eliminating most potential manure runoff through WISE aeration as the first step.
The paradigm change summary:
Aeration provides aerobic bacteria based manure decomposition while in storage.
Aerobic bacteria produce only carbon dioxide, which is considered carbon neutral when converting manure’s nutrients to fertilizer, reduced greenhouse gas (Aerobic gives off no other greenhouse gasses such as methane or oxides, and few odors)
“No odor” allows direct distribution of decomposed manure nutrients onto crops during growing season. (Distribution is done during growing season, using automated irrigation equipment).
Low-cost automated manure distribution reduces farm operation costs, but also allows the nutrients to be distributed to equal acres during a wider application time frame (not limited to when crop land is barren in spring or before fall freezeup.)
A wider application time frame allows multiple applications at smaller doses onto growing crops. Depending on nutrient application goals and equipment, irrigation rates can be as little as 1/8th inch of water, multiple times through the year, instead of one large dose.
Irrigation equipment is likely not operating when potential runoff conditions are pending, especially when the entire spring/summer/fall periods are available for distribution.
When nutrients are applied onto growing crops at low dosage rates during periods when irrigation is desired, very little potential for runoff is present. Only a small portion of 1/8” of water onto a crop canopy rarely reaches the ground. The nutrient rich water quickly binds with the dry surface soil when it does get past the crop canopy during summer application.
Current manure distribution distribution requires that most farmers fight to get raw manure distributed onto cropland before spring planting (which is often a wet time of year), OR after crops are harvested and bales removed. Although farmers and regulators wish that all manure handling is performed before freezeup, it is not the case: It happens more than anyone admits. Manure application to frozen ground is an understated and unquantified manure runoff cause. Such runoff can be eliminated by the new paradigm of application onto growing crops.
Further, the “side use” of treated effluent has significant benefit compared to raw manure. Aerobic Bacteria-Laden Effluent (ABLE water) is extremely proficient in its use within flume systems and for automatic flushing of alleys. The aerobic bacteria within the treated water is “hungry” to go to work, to pick up fresh food as it passes over the floor/alley, on its way back to the storage pond.
The layman’s explanation is similar to urban water delivery pipes and wastewater pipes buried within city streets:
Historically, dairy operators quickly learned that fresh well water will create a “slime” on surfaces, causing extremely slippery floors and alleys which injure cows. To eliminate much of the slipperiness, they stopped using fresh water and instead used raw manure from the pond. In many cases, they would add water to the pond, when manure got too thick and again caused slippery areas.
Unseen by most people are the 2 pipe systems under streets carrying our water and sewer. Factually, one pipe has slime, and the other pipe is amazingly clean: While acknowledging the newspaper notices that fire hydrants are going to be “flushed” several times/year, most don’t realize the purpose for doing so is to flush the slime from our drinking water pipes! The slime is not toxic to humans due to chlorination, but its buildup reduces pipe capacity, and its color is unpleasant to see in drinking water. In the case of unaerated fresh water used at farms, it tends to grow the slime that dairymen simply can’t afford on their alleys/floors.
Meanwhile, most people won’t look into a sewer manhole to note how “clean as a dinner plate” it looks! Sewerage pipes are designed for high capacity peak flow but normally runn at very low levels. This allows tremendous aeration activity within the system as water tumbles at manholes and as flows change direction. Thus, the aeration, food, and bacteria within properly operating sewer systems have very little odor, with the bacteria laden effluent continuously cleaning the sewer pipe. Sewer Pipes indeed look “brand new” even after operating for decades! Those who effectively aerate their manure pond water so they have high aerobic populations within the effluent, and use that effluent for flushing alleys and flumes are quite happy with the resultant cleaning of the alleys, floors, and flumes.
Lastly, ABLE water likely has traits of “compost tea”: Compost Tea is made by steeping in water, a quantity of completed compost, rich with soluble nutrients, bacteria, fungi, protozoa, nematodes and microarthropods. After removing the steeped compost solids, the remaining effluent is rich with those items recognized by many as necessary for building the soil and most effective for plant growth. The tea is to be used quite soon after it is created, but aeration can lengthen the storage period. Within aerobically treated manure ponds, because aeration is being performed continuously, compost tea-like benefits are anticipated to be included to crops having the WISE treated effluent application.
What did we do?
A basic hypothesis for WISE technology was developed in 2014 to explain why aeration levels are significantly higher compared to bubble blower technology. This hypothesis explains how/why results are being obtained and allows purposeful thought on how to maximize performance.
Meanwhile, engineering solutions were developed for the two main issues of equipment available at the time: 1) Previous equipment was heavy and required boom trucks/cranes to install/remove it for servicing (250 to 900 lb.), and 2) The propeller orientation/shape would inherently draw in stringy material that wraps on the propeller shaft, which then requires removal (see problem 1). New equipment was designed that weighs less than 120 lb. and is easily installed by hand (Figure 1).
Figure 1. One of two WISE technology models, this for open ponds (44” wide). The other model fits through a doorway to be installed in the manure storage pits of deep-pit hog barns.
What have we learned?
After years of testing the new design, the equipment proved to be able to operate without inviting stringy material to wrap on the propeller and to be easy to handle by hand. The design was declared an engineering success and marketing began.
In addition, nitrogen retention rates for aerobic manure treatment are much higher than published, most likely due to the traditional domestic wastewater treatment process assumptions of the 1970’s and the use of partial aeration, due to high costs of bubble blowers, instead of continuous aeration used within WISE aeration activity.
Prior to the 2018 North American Manure Expo, data was collected at 3 different farms in the Brooking SD area, each farm having a different brand/style of providing aeration. Due to the uncontrolled variables, results varied within each farm and also varied from the other farms. Although no clear specific results were determined, one specific trend was that installing equipment at a higher operational rate (1 device/50 animal units) than the study used (1 device/70animal units), offered higher nitrogen retention than can be expected from the NRCS funded study, which is higher than currently published aeration rates. This leads me to believe that there may be some misunderstood biological process for retaining nitrogen within aerobically treated effluent using WISE aeration. It appears there are some things unequivocally misunderstood about aerobic manure treatment and the nutrients retained, most likely also associated with the items commonly identified/targeted with Compost Tea discussions. The potential for changing the current manure handling paradigm to one where odor is not an issue, and application of manure nutrients onto growing crops which might also reduce manure runoff warrants further study.
The presentation will also touch on some basic misunderstandings about ammonia/ammonium, provide “do’s” and “don’ts” of installations and/or studies, and identify additional subjects for study.
What are the next steps?
Associated technology is being developed to perform foliar application. If farmers can’t handle manure differently, why would they do additional work, just to distribute it the same way they do now? The presentation will include basic information for a Self-Propelled Extremely Wide Portable Linear Irrigator (SPEWPLI). This equipment is projected to be able to irrigate/fertigate a full 160-acre field in 5 passes, and then be quickly moved to the next field. It is anticipated that manure pumpers would use existing equipment to deliver liquid manure to fields and use the SPEWPLI equipment as an alternative to conventional drag-hose injection. Foliar feeding has proven beneficial, applying nutrients directly onto growing crops (in canopy) when they best increase yields. By changing the distribution window to summertime, farmers don’t need to apply only in spring or in fall, or leave fields un-planted so manure can be applied in the summer.
While most farmers will not spend money to buy technology which only rids manure of odor while they continue to handle it as they have in the past, since there is very little economic return for only controlling odor, there are other aspects of WISE aeration technology to provide economic return, which then provides odor relief as a “free” benefit.
More information is needed on the benefits of distributing manure nutrients directly to growing crops and on the economics of low-cost, automated systems.
More information is needed in maximizing aeration for the energy used by way of this technology.
More information is needed in how nitrogen can possibly be tied up and reserved by the other bacteria, fungi, protozoa, nematodes and microarthropods within compost tea-like effluent.
A listing of such subject study items, likely to be doctorate dissertation level projects, will be included in the presentation.
Because our brand resolves issues that other equipment has, we will make it available for academic study at field sites and for others to use for additional research in the use of WISE aeration technology.
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.
The main purpose of this research project is an evaluation of the current products available in the open marketplace for using in deep pit swine manure structure as to their effectiveness in mitigation of odors and reduction of hydrogen sulfide (H2S), ammonia (NH3), 11 odorous volatile organic compounds (VOCs) and greenhouse gas (CO2, methane and nitrous oxide) emissions from stored swine manure. At the end of each trial, hydrogen sulfide and ammonia concentrations are measured during and immediately after the manure agitation process to simulate pump-out conditions. In addition, pit manure additives are tested for their impact on manure properties including solids content and microbial community.
What Did We Do?
Figure 1. Reactor simulates swine manure storage with controlled air flow rates.
We are using 15 reactors simulating swine manure storage (Figure 1) filled with fresh swine manure (outsourced from 3 different farms) to test simultaneously four manure additive products using manufacturer recommended dose for each product. Each product is tested in 3 identical dosages and storage conditions. The testing period starts on Day 0 (application of product following the recommended dosage by manufacturer) with weekly additions of manure from the same type of farm. The headspace ventilation of manure storage is identical and controlled to match pit manure storage conditions. Gas and odor samples from manure headspace are collected weekly. Hydrogen sulfide and ammonia concentrations are measured in real time with portable meters (both are calibrated with high precision standard gases). Headspace samples for greenhouse gases are collected with a syringe and vials, and analyzed with a gas chromatograph calibrated for CO2, methane and nitrous oxide. Volatile organic compounds are collected with solid-phase microextraction probes and analyzed with a gas chromatography-mass spectrometry (Atmospheric Environment 150 (2017) 313-321). Odor samples are collected in 10 L Tedlar bags and analyzed using the olfactometer with triangular forced-choice method (Chemosphere, 221 (2019) 787-783). To agitate the manure for pump-out simulation, top and bottom ‘Manure Sampling Ports’ (Figure 1) are connected to a liquid pump and cycling for 5 min. Manure samples are collected at the start and end of the trial and are analyzed for nitrogen content and bacterial populations.
The effectiveness of the product efficacy to mitigate emissions is estimated by comparing gas and odor emissions from the treated and untreated manure (control). The mixed linear model is used to analyze the data for statistical significance.
What we have learned?
Figure 2. Hydrogen sulfide and ammonia concentration increased greatly during agitation process conducted at the end of trial to simulate manure pump-out conditions and assess the instantaneous release of gases. The shade area is the initial 5 minutes of continuous manure agitation.
U.S. pork industry will have science-based, objectively tested information on odor and gas mitigation products. The industry does not need to waste precious resources on products with unproven or questionable performance record. This work addresses the question of odor emissions holistically by focusing on what changes that are occurring over time in the odor/odorants being emitted and how does the tested additive alter manure properties including the microbial community. Additionally, we tested the hydrogen sulfide and ammonia emissions during the agitation process simulating pump-out conditions. For both gases, the emissions increased significantly as shown in Figure 2. The Midwest is an ideal location for swine production facilities as the large expanse of crop production requires large fertilizer inputs, which allows manure to be valued as a fertilizer and recycled and used to support crop production.
Future Plans
We develop and test sustainable technologies for mitigation of odor and gaseous emissions from livestock operations. This involves lab-, pilot-, and farm-scale testing. We are pursuing advanced oxidation (UV light, ozone, plant-based peroxidase) and biochar-based technologies.
Daniel S. Andersen, Assoc. Prof., Iowa State University
David B. Parker, Ph.D., P.E., USDA-ARS-Bushland
Additional Information
Heber et al., Laboratory Testing of Commercial Manure Additives for Swine Odor Control. 2001.
Lemay, S., Stinson, R., Chenard, L., and Barber, M. Comparative Effectiveness of Five Manure Pit Additives. Prairie Swine Centre and the University of Saskatchewan.
Maurer, D., J.A. Koziel. 2019. On-farm pilot-scale testing of black ultraviolet light and photocatalytic coating for mitigation of odor, odorous VOCs, and greenhouse gases. Chemosphere, 221, 778-784; doi: 10.1016/j.chemosphere.2019.01.086.
Maurer, D.L, A. Bragdon, B. Short, H.K. Ahn, J.A. Koziel. 2018. Improving environmental odor measurements: comparison of lab-based standard method and portable odour measurement technology. Archives of Environmental Protection, 44(2), 100-107. doi: 10.24425/119699.
Maurer, D., J.A. Koziel, K. Bruning, D.B. Parker. 2017. Farm-scale testing of soybean peroxidase and calcium peroxide for surficial swine manure treatment and mitigation of odorous VOCs, ammonia, hydrogen sulfide emissions. Atmospheric Environment, 166, 467-478. doi: 10.1016/j.atmosenv.2017.07.048.
Maurer, D., J.A. Koziel, J.D. Harmon, S.J. Hoff, A.M. Rieck-Hinz, D.S Andersen. 2016. Summary of performance data for technologies to control gaseous, odor, and particulate emissions from livestock operations: Air Management Practices Assessment Tool (AMPAT). Data in Brief, 7, 1413-1429. doi: 10.1016/j.dib.2016.03.070.
Acknowledgments
We are thankful to (1) National Pork Board and Indiana Pork for funding this project (NBP-17-158), (2) cooperating farms for donating swine manure and (3) manufacturers for providing products for testing. We are also thankful to coworkers in Dr. Koziel’s Olfactometry Laboratory and Air Quality Laboratory, especially Dr. Chumki Banik, Hantian Ma, Zhanibek Meiirkhanuly, Lizbeth Plaza-Torres, Jisoo Wi, Myeongseong Lee, Lance Bormann, and Prof. Andrzej Bialowiec.
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.
In this mesophilic solid-state anaerobic co-digestion study, interaction among process parameters were investigated. To achieve this, four treatments were considered based on two carbon to nitrogen ratios (34 and 28). The treatments were DMCS34 – Dairy manure, inoculum, and untreated corn stover with C/N ratio of 34; DMCS28 – Dairy manure, inoculum, and untreated corn stover with C/N ratio of 28; DMPCS34 – Dairy manure, inoculum, and washed pretreated corn stover with C/N ratio of 34; and DMPCS28 – Dairy manure, inoculum, and washed pretreated corn stover with C/N ratio of 28. 1500g of each of this treatment was introduced into a 3.5L digester subjected to a temperature of 35oC. Samples from each treatment were analyzed for ADF, NDF, ADL, ORP, pH, volatile fatty acids concentration and composition, alkalinity, and ammonia-nitrogen at the start and end of the experiment. Also monitored and measured was the hydrogen sulphide, methane composition and biogas yield.
What Have We Learned?
In line with literatures, co-digestion of dairy manure with pretreated or untreated corn stover reduced inhibitory potential of dairy manure. For instance, propionic acid is one of such inhibitory substance to methanogens at 900 mg/L concentration. From Figure 1 propanoic concentration for all the treatments (DMPCS34, DMPCS28, DMCS34, and DMCS28) relative to the dairy manure was significantly reduced by at least 40 % (p < 0.05). Hence, these treatments all had propanoic concentration below 900 mg/L except for DMPCS34. The contrary trend with DMPCS34 treatment might suggest the role of high C/N in propanoic production rate. Furthermore, we also observe that pretreatment lessen this dilution effect, as propanoic concentration was higher with the pretreated treatments (DMPCS34 and DMPCS28).
Figure 1: VFA composition and concentration of dairy manure and ingestates
On interaction between ORP relationship with pH, our result shows that there was a strong negative correlation between pH and ORP. As the ORP increases, the pH decreases. This could be attributed to high VFA production beyond the buffering capacity of the alkalinity in the influent. The slight decrease observed in the ORP after 25 days (Figure 2) detention time could be attributed to 33 mL of NaHCO3 added to raise the pH. However, this seems to have no obvious impact on the pH, as the pH remains between 4.8 – 5.2. Similar trend was observed for DMCS28 and DMPCS28 influent with more pronounced ORP increase from between -390 mV at the start of the experiment to +131 mV at the end of the experiment.
Figure 2: Interaction between pH and ORP for DMCS34 and DMPCS34.
A more complex interaction among VFA/Ammonia, pH, ORP and VFA/Alkalinity investigated in Figure 3 shows low growth in VFA/Alkalinity relative to VFA/Ammonia, an indication that ammonia concentration was low relative to other alkaline in the digester. This might be due to low ammonia mineralization or the generation rate might be slower compared with VFA production rate. Furthermore, at the end of the experiments, the digestates all had VFA/Alkalinity values that exceeded 0.9 (Figure 3), a stable process condition threshold for anaerobic digestion.
Figure 3: Relationship between some process parameters and ORP
Unlike Figure 3, there was no clear interaction among ORP and VFA composition ratio after the experiment (Figure 4). However, we observed that acetic to propionate acid ratio in our study was above the threshold 0.7 recommended for effective anaerobic digestion. Interestingly, acetic to butyric ratio was inversely proportional to the butyric to propanoic ratio (Figure 4).
Figure 4: Relationship between some process parameters mostly related to VFA and ORP
Future Plans
We intend to conduct more investigation on these process parameters in order to have a more defined values for a suitable solid-state anaerobic co-digestion process.
Authors
Shafiqur Rahman, Associate Professor, Agricultural & Biosystems Engineering Department, North Dakota State University
Ademola Ajayi-Banji, Graduate Student, Agricultural & Biosystems Engineering Department, North Dakota State University
Additional Information
Will be available at North Dakota State University library by 2020.
Acknowledgements
North Dakota State University Development Foundational Grant.
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.
Solid state anaerobic co-digestion (SSCoD) has attracted huge attention in the renewable energy industry due to the potential to solve nutrient imbalance challenge. However, SSCoD potential as biogas source is often limited except the process parameters are systematically optimized. Hence, in this study, we investigated the impact of 4%-NaOH-pretreatment and two agitation frequencies (two-day and seven-day periodic agitation), being part of the process parameters, on biogas composition and methane yield.
What Did We Do?
In our study, four solid-state treatments (DMPCSuw, DMPCSuw2, DMPCS, and DMCS) prepared from the co-digestion of dairy manure and corn stover under total solid of 16% were used to examine the effect of pretreatment with or without washing and agitation frequency on biogas production and composition. Treatment DMPCSuw2 represents dairy manure, inoculum, and unwashed pretreated corn stover agitated every two-days; Treatment DMPCSuw represents dairy manure, inoculum, and unwashed pretreated corn stover agitated every seven-days; Treatment DMPCS represents dairy manure, inoculum, and washed pretreated corn stover agitated every seven-days; and Treatment DMCS represents dairy manure and inoculum with untreated corn stover agitated every seven-days. 1000g of these treatments were loaded into four litres working volume PVC digesters installed in a thermostatically-controlled-water bath set at 37oC.The gas composition (methane, carbon dioxide and hydrogen sulphide) and yield from these treatments were monitored and quantified. Other process parameters investigated before and after the digestion process were ADF, NDF, ADL, ORP, pH, volatile fatty acids concentration and composition, alkalinity, and ammonia-nitrogen. Also investigated was the volatile solids.
What Have We Learned?
Considering treatments with either of the two processes (washing and unwashing) after pretreatment, we observed that treatments prepared with unwashed 4% NaOH pretreated corn stover (DMPCSuw and DMPCSuw2) showed significantly higher acetic acid production (p < 0.05), irrespective of agitation frequency (Figure 1). Acetic concentration at the end of the experiments was over 50 g/L (Figure 1). This suggests higher biogas yield and invariably more energy generation.
Figure 1: VFA composition of treatments
Furthermore, as shown in Figure 2, there was significantly higher holocellulose degradation in the treatments with unwashed 4% NaOH pretreated corn stover (DMPCSuw and DMPCSuw2) compared with DMCS and DMPCS (P < 0.05). Furthermore, cellulose and holocellulose was over 50% in the DMPCSuw and DMPCSuw2 treatments (Figure 2). These further substantiate the effectiveness of DMPCSuw and DMPCSuw2 treatments in energy generation from the co-digestion of dairy manure and corn stover under solid-state condition.
Figure 2: Holocellulose degradation in treatments
High sulphide production (> 5000 ppm) in the DMCS and DMPCS treatments on the 10th days might be the reason for the low methane composition (Figure 4). This was because aside from the potential competition of sulphur reducing bacteria with methanogens which obviously affected the anaerobic process in treatments DMCS and DMPCS, the digesters for DMCS and DMPCS treatments equally for failure after the third week.
Consistent methane composition after the third week of our experiment and the low sulphide production from DMPCSuw and DMPCSuw2 treatments (Figures 3 & 4) suggest that, pretreatment without washing could enhance biogas yield and methane composition.
However, there was no significant difference between 2 days and 7 days agitation frequency in our study, a trend which suggests that 7-days agitation frequency will likely minimize agitation energy input for the SSCoD study.
Figure 3: Weekly hydrogen sulphide production from the treatmentsFigure 4: Weekly methane composition from the treatments
Future Plans
We intend to improve methane production from our unwashed treatments, this will add more economic value to the solid-state anaerobic co-digestion process.
Authors
Shafiqur Rahman, Associate Professor, Agricultural & Biosystems Engineering Department, North Dakota State University
Ademola Ajayi-Banji, Graduate Student, Agricultural & Biosystems Engineering Department, North Dakota State University
Additional Information
Will be available at North Dakota State University library by 2020.
Acknowledgements
North Dakota State University Development Foundational Grant.
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2019. Title of presentation. Waste to Worth. Minneapolis, MN. April 22-26, 2019. URL of this page. Accessed on: today’s date.
The University of Nebraska – Lincoln (UNL) Animal Manure Management (AMM) Team has supported the environmental stewardship goals of Nebraska’s livestock and crop producers for many years using multiple traditional delivery methods, but recently recognized the need to more actively engage with clientele through content marketing activities. A current programming effort by the AMM Team to increase efficient manure utilization on cropland in the vicinity of intensive livestock production is the foundation for an innovative social media campaign.
What did we do?
Figure 1. Content marketing plan to direct traffic to the AMM Team website.
While traditional extension outputs remain valuable for supporting the needs of clientele who actively seek out information on a topic, “content marketing” is a strategic tactic by which information is shared to not only attract and retain an audience, but to drive impactful action. Social media platforms are popular tools for delivery of current, research-based information to clientele; a key barrier to effectively using social media for content marketing by the project directors has been time. For instance, using Twitter efficiently requires regular attention to deliver messages frequently enough to remain relevant and to do so at times when user activity characteristics demonstrate the greatest opportunity for posts to be viewed and disseminated. Because this proved to be a challenge, a content marketing plan (Figure 1) was initiated using “waste to worth” as the topic of focus.
Three major components were identified as being critical to the success of the project (Figure 2): design of high-quality graphics that are tied to online content and resources and are suitable for use on Twitter, Facebook, or other social media platforms; development of a content library containing packaged content (graphic + suggested text for social media posts) that is easy to navigate and available for partners to access and utilize; and development of a communication network capable of reaching a broad audience.
Graphics
Figure 2. Components identified for successful content marketing effort.
An undergraduate Agricultural Leadership, Education and Communication (ALEC) student was recruited to support graphical content development using three basic guidelines: 1) Eye-catching but simple designs; 2) Associated with existing content hosted online; and 3) Accurate information illustrated Canva.com was utilized by team members to design, review and edit social media content (Figure 3).
Content Library
Completed graphics are downloaded from Canva as portable network graphics (*.png) and saved to Box folders, by topic, using a descriptive title. When posting to social media, hashtags, mentions and links to other content help (a) reach users who are following a specific topic (e.g. #manure), (b) recognize someone related to the post (e.g. @TheManureLady) and (c) direct users to more content related to the graphic (e.g. URL to online article). For our content library, each graphic is accompanied by a file containing recommended text (Figure 4) that can be copied and pasted into Twitter or Facebook.
Figure 3. Graphical content examples for the “waste to worth” projectFigure 4. Sample text to accompany a related image when posting on social media
Communication Network
Figure 5. Content distribution network diagram.
Disseminating our messages through outlets outside the University was identified as a critical aspect of achieving the widespread message delivery that was desired. As such, agricultural partners throughout Nebraska were asked to help “spread the word about spreading manure” by utilizing our content in their social media outputs, electronic newsletters, printed publications, etc. Partners in this project include nearly 30 livestock and crop commodity organizations, media outlets, agricultural business organizations, and state agencies in Nebraska (Figure 5).
The effort to distribute content through the established communication network was launched in September 2018. Each month, three to four graphics with accompanying text are placed in a Box file to which all partners in the distribution network have access. Partners are notified via e-mail when new content is released. Folders containing prior months’ releases remain available to allow partners to re-distribute previous content if they wish.
What we have learned?
Since launching, 34 partnering organizations (Figure 6) have helped disseminate content to 50,000+ producers, advisors, allied industry members, and related professionals each month. Invited media appearances (radio and television) by team members have increased substantially in the past six months. For instance, the Nebraska Pork Producers Association hosts a weekly “Pork Industry Update” on a radio station that is part of the Rural Radio Network. Team members have recorded numerous interviews for broadcast during this weekly programming spot.
Figure 6. Partner organizations contributing to content distribution.
Page views within the AMM Team’s website (manure.unl.edu) increased by 139% from the fourth quarter of 2017 to the fourth quarter of 2018. Additional analytics are being collected to better define routes by which traffic is reaching the AMM Team’s website.
Future Plans
A survey is being prepared for distribution to audiences targeted through this project to assess impacts of this effort on changes in knowledge and behavior related to responsible use of manure in cropping systems, recognition of the AMM Team as a trusted source for manure and nutrient management information in Nebraska, and quality of AMM Team outputs.
Author
Amy Millmier Schmidt, Associate Professor, Biological Systems Engineering and Animal Science, University of Nebraska-Lincoln (UNL), aschmidt@unl.edu
Co-authors
Rick Koelsch, Professor, Biological Systems Engineering and Animal Science, UNL
Abby Steffen, UG Student, Ag Leadership, Education and Communication, UNL
Additional Information
Sign up for monthly notifications about new content from the UNL Animal Manure Management team at https://water.unl.edu/newsletter. Follow team members and the AMM Team.
Funding sources supporting this effort include We Support Ag, the Nebraska Environmental Trust, and the North Central Sustainable Agricultural Research and Education (NC-SARE) program.
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.
Animal manures contain nutrients [primarily nitrogen (N) and phosphorus (P)] and organic material that are beneficial to crops. Unfortunately, for economic and logistics reasons, dairy 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, and is often in excess of crop demands. We previously described, 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 postulated that the MAPHEX System was also capable of removing odor and microbes, and of concentrating alkalinity into a solid, economically transported form. In this study the MAPHEX System was shown to be highly versatile at removing greater than 90 % of the phosphorus from a wide range of dairy manures. In addition to that, the study showed that the System is also capable of concentrating and recovering alkalinity from manures, while also removing over 80 % of microbes and reducing the odor of the effluent applied to fields by half. 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.
Kleinman, Peter (USDA-ARS); Hristov, Alex (Pennsylvania State University); Bryant, Ray (USDA-ARS)
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.
A 1200-hd solid-liquid separation finishing barn was built in Missouri for improved manure management and air quality. The facility has a wide V-shaped gutter below slatted flooring (Figure 1), which continuously drains away liquids. A scraper is used to collect the solids, which are then managed separately. Field sampling and research were conducted to evaluate the performance of the solid-liquid separation finishing barn in improving manure nutrient management, potential nutrient/water recycling based on filtration, and barn construction and operating costs.
What did we do?
The barn (built in 2010) was closely monitored for manure production and nutrient content, and operating costs. Laboratory-scale pretreatments and filtrations were conducted to evaluate the practicality of nutrient/water recycling from the separated liquid manure.
What we have learned?
The daily liquid manure production averaged 885 gallons and daily solid manure production averaged 299 gallons (about ¼ of the total manure volume). The separation system removed 61.7%, 41.7%, 74.8%, and 46.2% of the total manure nitrogen, ammonium, phosphorous, and potassium, respectively, with the collected solids. The filtration results indicate that the microfiltration and reverse osmosis were time and energy intensive, which was probably constrained by the relatively small-scale unit (inefficient compared with larger units), small filter surface area, and high concentration of dissolved nutrients.
The construction cost of the solid-liquid separation barn with solid manure storage was $323,000 ($269/pig-space, in 2010), 17% higher compared to the traditional deep-pit barn ($175 to $230/pig-space). It is likely that the solid-liquid separation barn will become less expensive when more barns of similar design are built, and the conveyor system can be improved and simplified for less maintenance and lower costs. Additional electricity cost was $331 per year for daily operation of the scraper and conveyor systems, and pumping the separated liquid manure fraction. The additional maintenance cost of the scraper system averaged $1,673/year. A net gain of $3,975/year was observed when considering the value of the separated manures, cost of land application, and annual maintenance cost.
A payback period of 15.1 years on the additional investment was estimated, when compared with the popular deep-pit operation. However, the payback period can be reduced by many factors, including improved conveyor system and growing popularity of the barn design in an area. When the distance to transport the slurry manure was increased from 5 miles to 7.5 and 10 miles, the payback periods became 12.7 and 11.3 years, respectively. The solid-liquid separation barn was shown to have better air quality when compared with deep-pit barns based on monthly measurements of ammonia and hydrogen sulfide concentrations.
Impacts/Implications of the Research.
This study monitored the manure production of a commercial finishing barn utilizing a solid-liquid separation system. Overall, we can conclude that the final results obtained from monitoring the total manure production rate, air quality exiting the barn fans, and the pig growth rates made sense relative to other comparative sources. The overall results indicate that the barn design can attain some valuable benefits from separating the solid and liquid streams. About a quarter of the manure volume was collected and managed as nutrient-dense solid manure (defined as ‘stackable’). The solid manure held 80% of the total solids and nearly 75% of the phosphorous.
Take Home Message
There are alternative barn designs and manure management systems (relative to lagoon and deep-pit operations) that should be considered when planning for a new operation or expansion. Considerations should include the need to better manage manure nutrients and improve air quality for human and animal occupants.
Future plans
Further consideration of the manure management, including work load and major- and micro-nutrients need to be furthered analyzed. Future research may look into application of a larger-scale crossflow system to see if nutrient removal and flow rates can be improved significantly. Future research may focus on improving manure filtrate flow, and determining the cost of installation and upkeep for a filtration unit that can operate at the level of a farm operation. Extrapolating the costs off of bench-scale model does not seem remotely indicative of the true cost, due to improved efficiency and power of larger unit.
Authors
Lim, Teng (Associate Professor and Extension Agricultural Engineer, Agricultural Systems Management, University of Missouri, limt@missouri.edu)
Brown, Joshua (University of Missouri); Zulovich, Joseph (University of Missouri); and Massey, Ray (University of Missouri).
Funding for this research project was provided by the National Pork Checkoff and University of Missouri Extension.
Figure 1. The V-shape pit with automated manure scraper and trough at center (Left), and gravity draining of liquid manure from the trough to the sump pit (Right).Figure 2. The storage shed for solid manure to the north of the modified scraper barn (Left), and stored solid manure (Right).
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.
Advancedmanure 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.
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