nutrient recovery – Page 2 – Livestock and Poultry Environmental Learning Community

March 5, 2019July 14, 2020

Results of Nutrient Recovery System Installed on Large Scale Dairy Operation After 2-years of Operation

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Purpose

For centuries, farmers have disposed of manure by simply spreading it on the land. It is a natural fertilizer. Today, that practice is no longer considered the best solution. Field spreading is now understood to contribute to a growing global problem of the pollution of water, soil, and air. Consequently, U.S. dairy farmers face increased fiscal and operational pressure from the progression of ever tightening environmental regulations. Conventional handling of manure also imposes a number of operational challenges (limitations for storage, land application and irrigation, settlement in lagoons, high manure hauling costs, etc.) and typically requires a relatively large land base to allow adequate nutrient management.

In Indiana, a dairy that was daily producing thousands of tons of livestock waste was investigating how technology could capture the valuable nutrients remaining in their cow manure after it had gone through the farm’s anaerobic digestion process. Their goal was to convert the manure/digestate into a nutrient rich cake that could be easier managed and made into fertilizer, and the liquid clean enough to be used unrestricted for land application.

The farm’s key operational deliverables were 1) to reduce the manure’s handling and transportation costs, 2) allow for precision applications of the processed manure as carbon-based fertilizer and 3) allow for re-use of nutrient reduced liquid for field irrigation.

What did we do?

The dairy farm chose to implement a nutrient recovery technology from Trident Processes LLC. The technology separates the manure/digestate into three fractions: 1) cellulosic fiber, 2) a concentrated cake of nutrient enriched solids, and 3) water with about 1% remaining solids.

Trident’s turn-key system, consisting of different mechanical and chemical components, processes the manure and diverts each separated fraction into their separate spaces. Sensors and programmable controls (PLC) allow for smooth operation, requiring minimal operator attendance. The entire system can be monitored, controlled and diagnosed remotely.

The manure is fed into the system following the digestion process. The initial step is the extraction of the large fiber, which is done via a rotary screen conditioner. The wetted material separates, with the effluent water and fine solids sifting down through the screen while the larger fiber is retained. This step is critical as it ensures the fine particles, which contain the nutrients, are sent down stream for further treatment.

FIBER: The extracted fiber is sent to a screw press for further dewatering. This renders it as a 30% dry cellulosic fiber biomass that is ideal for recycling as cow bedding or other biomass use. Any liquid squeezed from the fiber is diverted to join the fine solids stream.

SOLIDS: The effluent water and solids are sent to a dissolved air flotation (DAF) tank. Polymerization ensures effective flocculation of the feedstock, resulting in a concentration of the nutrient rich particles that float to the surface. The sludge formed on the surface is skimmed off the top and gravity fed into a multi-disc press for second-stage dewatering. The press gently dewaters and thickens the recovered solid/nutrient sludge into a 25% solids, nutrient rich cake.

WATER: The final effluent water, now nutrient reduced, contains less than 1.2% solids and is sent to the lagoon for storage. The water is then reused for irrigation through efficient pivot systems or as operational water on the farm.

What have we learned?

By implementing Trident’s Nutrient Recovery System, the farms’ objectives have been met and/or exceeded. After running for nearly two years the system is producing the following statistics:

• Fully automated operation requiring about 1 hr/shift for operator attendance (visual checks)

• 98% system uptime

• Polymer costs: $0.06 – $0.08/day/cow

• Reduction of handling and irrigation costs: $ 0.01/gal (conventional) vs $0.003/gal (center pivot)

• $250,000/yr electrical power savings with MD Press vs. centrifuge

• 73,000+ ton/yr nutrient cake produced

• 81% P, 70% organic N (54% TKN), and 20% K is the average nutrient capture rate

• 1% (max.) solids in the effluent water sent to lagoons

• 99% Suspended solids captured

Future Plans

Dairy farm: A fertilizer plant will go live in the near future, allowing the farm to sell their concentrated nutrients to the plant as feedstock for custom fertilizer production.

Technology provider: 2nd Phase effluent treatment to capture and retain the solid and nutrient fraction of the existing process, allowing to meet stream discharge standards and comply with BOD / COD levels. Bench scale testing is completed. Farm scale pilot testing is scheduled to run from March 2017-December 2017.

Corresponding author, title, and affiliation

Richard Shatto (Senior Partner at Point Nexus Consulting), Frank Engel (Director Marketing at KPD Consulting Ltd.)

Corresponding author email

frank.engel@kpdconsulting.ca

Additional information

https://youtu.be/PvaTGmyws-w (Carl Ramsey’s presentation at Indiana Dairy Forum)

http://www.progressivedairy.com/topics/manure/prairie-s-edge-dairy-on-pa… (Progressive Dairyman article)

http://tridentprocesses.com/documents/case-study-trident-nutrient-recove… (Newtrient case study)

https://are.wisc.edu/manure-processing/ (manure management project with University of Wisconsin)

http://www.foodqualityandsafety.com/article/nutrient-recovery-improves-s… (Nutrient Recovery Improves Sustainability article in Food Quality & Safety Magazine)

Acknowledgements

Carl Ramsey, Environmental Manager at Prairie’s Edge Dairy Farm

Soil Net LLC, Dr. Aicardo Roa (strategic partner for chemical separation process)

Leap Tech, R.C. Ludke (strategic partner for automation)

March 5, 2019March 6, 2019

Poultry Digestion – Emerging Farm-Based Opportunity

While EPA AGSTAR has long supported the adoption of anaerobic digestion on dairies and swine farms, they have not historically focused on the use of anaerobic digestion on egg laying and other poultry facilities. This has been because the high solids and ammonia concentrations within the manure make anaerobic digestion in a slurry-based system problematic. Development of enhanced downstream ammonia and solids recovery systems is now allowing for effective digestion without ammonia toxicity. The process also generates dilution water, avoiding the need for fresh water consumption, and eliminating unwanted effluent that needs to be stored or disposed of to fields. The system produces high-value bio-based fertilizers. In this presentation, a commercial system located in Fort Recovery Ohio will be used to detail the process flow, its technologies, and the co-products sold.

Why Examine Anaerobic Digestion on Poultry Farms?

The purpose of this presentation is to supply a case study on a commercial poultry digestion project for production of combined heat and power as well as value-added organic nutrients on a 1M egg-layer facility in Ohio.

What did we do?

In this study we used commercial farm information to demonstrate that poultry digestion is feasible in regard to overcoming ammonia inhibition while fitting well into an existing egg-layer manure management system. Importantly, during the treatment process a significant portion of nutrients within the manure are concentrated for value-added sales, ammonia losses to the environment are reduced, and wastewater production is minimized due to recycle of effluent as dilution water.

What have we learned?

In this study, commercial data shows that ammonia and solids/salts levels that are potentially inhibitory to the biology of the digestion process can be controlled. The control is through a post-digestion treatment that includes ammonia stripping and recovery as ammonium sulfate as well as fine solids separation using a dissolved air flotation process with the addition of a polymer. The resulting treated effluent is sent back to the front of the digester as dilution water for the high solids poultry manure. The separated fine solids and the ammonium sulfate solution are dried using waste engine heat to produce a nutrient-rich fertilizer for off-farm sales. The stable anaerobic digestion process resulting from the control of potential inhibitors that might accumulate in the return water, if no post-treatment occurred, leads to production of a significant supply of electrical power for sales to the grid.

Demonstration at commercial scale shows the promise anaerobic digestion with post-digestion treatment and effluent recycle can play in a more sustainable poultry manure treatment system including managing nutrients for export out of impacted watersheds.

Future Plans

Future plans include continued work with industry in developing and/or providing extension capabilities around novel digestion and post-treatment processes for a variety of manures and on-farm situations. Expansion of such processes to poultry and other on-farm business plans will allow for improved reductions in wastewater production, concentrate nutrients for export out of impacted watersheds and do so within a positive economic business plan.

Authors

Craig Frear, Assistant Professor at Washington State University cfrear@wsu.edu

Quanbao Zhao, Project Engineer DVO Incorporated, Steve Dvorak, President DVO Incorporated

Additional information

Additional information about the corresponding author can be found at http://www.csanr.wsu.edu while information about the poultry project and the industry developer can be found at http://www.dvoinc.net. Numerous articles related to anaerobic digestion, nutrient recovery and separation technologies for climate, air, water and human health improvements can be found at the WSU website using their searchable articles function.

Acknowledgements

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.

March 5, 2019July 6, 2020

Development of Pilot Modules for Recovering Gaseous Ammonia from Poultry Manure

Purpose?

There is major interest from producers and the public in implementing best control technologies that would abate ammonia (NH₃) emissions from confined livestock and poultry operations by capturing and recovering the nitrogen (NH₃-N).

What did we do?

In this study, we continued investigating development of gas-permeable membrane modules as components of new processes to capture and recover gaseous ammonia inside poultry houses, composting facilities, and other livestock installations. The overall research objective was to improve poultry houses with the introduction of nitrogen emission capture technology. There were two milestones during the initial phase of the study: 1) to test ammonia recovery with gas-permeable membranes in a bench system using Maryland’s poultry manure; and 2) to construct and install a pilot ammonia recovery system at the UMES Poultry Research facility.

Figure 1. System for the recovery of gaseous ammonia from poultry waste using gas-permeable membrane module.

Figure 1. System for the recovery of gaseous ammonia from poultry waste using gas-permeable membrane module.

What have we learned?

The prototype ammonia recovery bench system using gas-permeable modules was moved from ARS-Florence to ARS-BARC in Sept. 2013 and tested during three consecutives runs using turkey and chicken manure mixes. The bench unit had two chambers: one was used with recirculating acid solution (1 N H₂SO₄) and the other was a control that used recirculating water. The control, which used water as the capture solution, was very effective at recovering the ammonia. This finding may lead to more economical ammonia recovery systems in the future.

Figure 2. Prototype ammonia recovery system using gas-permeable modules.

Figure 2. Prototype ammonia recovery system using gas-permeable modules.

Two pilot ammonia recovery systems using gas-permeable membranes were constructed at ARS-Florence and installed at the UMES poultry research facility in June 2014. One ammonia recovery module was developed using flat membranes mounted on troughs. The other module was developed using tubular gas-permeable membranes. The recovery manifolds were placed inside the experimental barns (400 chickens) hanging from the roof and close to the litter. Both systems were installed with the ammonia concentrator tanks outside the barns. They were tested continuously for four months without chickens in the barns. The first flock of birds was placed in the facility Feb. 2015 and also in a control facility without the ammonia recovery modules. The installed modules will demonstrate the ammonia recovery and the potential poultry production benefits from cleaner air.

Figure 3. Pilot ammonia recovery systems installed in a chicken barn at UMES Poultry Research Facility. At left is a recovery module that uses tubular gas-permeable membranes. At right is a recovery module that uses flat gas-permeable membranes.

Figure 3. Pilot ammonia recovery systems installed in a chicken barn at UMES Poultry Research Facility. At left is a recovery module that uses tubular gas-permeable membranes. At right is a recovery module that uses flat gas-permeable membranes.

Future plans?

The N recovery modules are being demonstrated at the University of Maryland Eastern Shore’s Poultry Research facility.

USDA seeks a commercial partner to develop and market this invention (Gaseous ammonia removal system. US Patent 8,906,332 B2, issued Dec. 9, 2014). http://www.ars.usda.gov/business/docs.htm?docid=763&page=5

Authors

Matias Vanotti, USDA-ARS, Florence, South Carolina matias.vanotti@ars.usda.gov

Vanotti, M.B.¹; Millner, P.D.²;Sanchez Bascones, M.³;Szogi, A.A.¹; Brigman, P.W.¹; Buabeng, F.⁴; Timmons, J.⁴; Hashem, F.M.⁴

¹USDA-ARS Coastal Plains Soil Water and Plant Research Center, Florence, SC, USA

²USDA-ARS Environmental Microbial and Food Safety, Beltsville, MD, USA

³University of Valladolid, School of Agric. Engineering, Palencia, Spain

⁴University of Maryland Eastern Shore, Dept. of Agriculture, Food and Resource Sciences, Princess Anne, MD, USA

Additional information

Szogi, A.A., Vanotti, M.B., and Rothrock, M.J. 2014. Gaseous ammonia removal system. US Patent 8,906,332 B2, issued Dec. 9, 2014. US Patent and Trademark Office, Washington, DC.

Rothrock Jr, M.J., Szogi, A.A., Vanotti, M.B. 2013. Recovery of ammonia from poultry litter using flat gas permeable membranes. J. of Waste Management. 33:1531-1538

“Recovery of ammonia with gas permeable membranes” research update at USDA-ARS-CPSWPRC website http://www.ars.usda.gov/Research/docs.htm?docid=22883#ammonia

Acknowledgements

We acknowledge NIFA Project “Novel Integration of Solar Heating with Electricity Generation Technology and Biofiltered Poultry Litter Biofertilizer Production System” and ARS Project 6657-13630-001-00D “Innovative Animal Manure Treatment Technologies for Enhanced Environmental Quality”. Funding by University of Valladolid/Banco Santander for participation of Dr. Sanchez Bascones as Visiting Scientist is also acknowledged.

March 5, 2019July 6, 2020

Improved Recovery of Ammonia From Swine Manure Using Gas-Permeable Membrane Technology and Aeration

Why Study Nitrogen Recovery from Manure?

Significant efforts are required to abate NH₃ emissions from livestock operations. In addition, the costs of fertilizers have rapidly increased in recent years, especially nitrogen fertilizer such as anhydrous ammonia which is made from natural gas. Thus, new technologies for abatement of ammonia emissions in livestock operations are being focussed on N recovery. This presentation shows a novel system that uses gas-permeable membranes to capture and recover ammonia from liquid manure, reducing ammonia emissions from livestock operations, and recovering concentrated liquid nitrogen that could be sold as fertilizer.

What Did We Do?

Nitrogen recovery from swine manure was investigated using a new technology that uses gas-permeable membranes at low pressure. The new process includes the passage of gaseous ammonia contained in the liquid manure through a microporous hydrophobic membrane and capture and concentrate with circulating diluted acid on the other side of the membrane. The membranes can be assembled in modules or manifolds. Membrane manifolds are submerged in the manure and the ammonia is removed from the liquid before it escapes into the air. The process involves manure pH control to increase ammonium recovery rate that is normally carried out using an alkali chemical. In this study a new strategy was tested to avoid the use of alkali chemicals. Instead of the chemical, we applied low-rate aeration and nitrification inhibitor to raise the pH and promote ammonia capture by the membrane system.

Figure 1. Diagram of ammonia recovery system using with gas permeable membranes and low-rate aeration

What Did We Learn?

Two studies were conducted to recover N from liquid swine manures containing high ammonia concentrations using a USDA patented gas-permeable membrane system. One study used raw liquid manure from the pit under slatted floor of a farrowing sow’s barn in Segovia, Spain. The second study used liquid swine manure effluent from a covered lagoon digester in North Carolina, USA. The new strategy that used low-rate aeration and nitrification inhibition worked quite well in both situations. In the first study using raw manure, the pH increased and the ammonium concentration was almost depleted: it declined from 2270 mg N/L to 20 mg N/ in 18 days. The ammonia that was removed was recovered efficiently in the concentrator tank (99% recovery efficiency). Using the same membrane manifold without the aeration protocol, the ammonium concentration in the manure decreased at a slower rate from 2330 mg N/L to 790 mg N/L in 18 days. The results obtained were consistent in the second study that used digested swine effluent. When low-rate aeration and nitrification inhibitor were added to the gas-permeable membrane reactor, ammonium concentration in the digester effluent decreased rapidly, from 3130 mg N/L to 96 mg N/L, in 5 days. The recovery efficiency was 98%. This N removal rate was 5 times faster than a control that used the same membrane reactor and conditions but operated without the aeration protocol. Overall results obtained in this work indicate the low-rate aeration is an economical alternative to chemical addition to increase ammonia availability and the capture of ammonia by gas-permeable membrane systems. This conclusion is supported by the very high removal and recovery efficiencies obtained resulting in an overall recovery of 95 to 98% of the initial ammonia in the manure.

Future Plans

On-farm demonstration studies will be conducted in 2015 in cooperation with Dr. John Classen, North Carolina State University, through an NRCS Conservation Innovation Grant (CIG) “Ammonia recovery from swine wastewater with selective membrane technology”. A mobile pilot unit will demonstrate recovery of ammonia from liquid manure effluents using the gas-permeable technology in three different manure collection systems: under floor belt system, scraper system, and anaerobic digester.

USDA seeks a commercial partner to develop and market this invention (Systems and Methods for Reducing Ammonia Emissions form Liquid Effluents and for Recovering Ammonia. US Patent Appl. SN 13/164,363 allowed Dec. 19, 2014) http://www.ars.usda.gov/business/docs.htm?docid=763&page=5

Authors

Matias Vanotti, USDA-ARS, Florence, South Carolina matias.vanotti@ars.usda.gov

Matias B. Vanotti¹, Maria C. Garcia-Gonzalez², Patrick J. Dube¹, Ariel A. Szogi¹

¹USDA-ARS, Coastal Plains Soil, Water, and Plant Research Center, Florence, SC

²Agriculture Technological Institute of Castilla and Leon (ITACyL), Valladolid, Spain

Additional Information

“Livestock Waste Management 2.0: Recycling Ammonia Emissions as Fertilizer” published in the November/December 2012 issue of Agricultural Research magazine http://www.ars.usda.gov/is/AR/archive/nov12/livestock1112.htm

“Recovery of ammonia with gas permeable membranes” research update at USDA-ARS-CPSWPRC website http://www.ars.usda.gov/Research/docs.htm?docid=22883#ammonia

Vanotti,M.B., Szogi,A.A. “Systems and Methods for Reducing Ammonia Emissions form Liquid Effluents and for Recovering Ammonia”. US Patent Appl. SN 13/164,363, filed June 20, 2011, allowed December 19, 2014. US Patent and Trademark Office, Washington, DC.

Garcia-Gonzalez, M.C., Vanotti, M.B., Szogi, A.A. 2015. “Recovery of ammonia from swine manure using gas-permeable membranes: Effect of aeration”. Journal of Environmental Management 152:19-26

Acknowledgements

This research was part of USDA-ARS National Program 214 Agricultural and Industrial Byproducts, Research Project 6657-13630-005-00D “Innovative Bioresource Management Technologies for Enhanced Environmental Quality and Value optimization”. Funding by INIA/FEDER Project CC09-072 is gratefully acknowledged.

March 5, 2019May 7, 2019

Thermal-Chemical Conversion of Animal Manures – Another Tool for the Toolbox

How Can Thermo-Chemical Technologies Assist in Nutrient Management?

Livestock operations continue to expand and concentrate in certain parts of the country. This has created regional “hot spot” areas in which excess nutrients, particularly phosphorus, are produced. This nutrient issue has resulted in water quality concerns across the country and even lead to the necessity of a “watershed diet” for the Chesapeake Bay Watershed. To help address this nutrient concern some livestock producers are looking to manure gasification and other thermo-chemical processes. There are several thermo-chemical conversion configurations, and the one chosen for a particular livestock operation is dependent on the desired application and final by-products. Through these thermo-chemical processes manure Factory processing volumes are significantly reduced. With the nutrients being concentrated, they are more easily handled and can be transported from areas of high nutrient loads to regions of low nutrient loads at a lower cost. This practice can also help to reduce the on-farm energy costs by providing supplemental energy and/or heat. Additional benefits include pathogen destruction and odor reduction. This presentation will provide an overview of several Conservation Innovation Grants (CIG) and other manure thermo-chemical conversion projects that are being demonstrated and/or in commercial operation. Information will cover nutrient fate, emission studies, by-product applications along with some of the positives and negatives related to thermo-chemical conversion systems.

What did we do?

Several farm-scale manure-to-energy demonstration projects are underway within the Chesapeake Bay Watershed. Many of these receive funding through the USDA-NRCS Conservation Innovation Grant program. These projects, located on poultry farms, are being evaluated for the performance of on-farm thermal conversion technologies. Monitoring data is being collected for each project which includes: technical performance, operation and maintenance, air emissions, and by-product uses and potential markets. Performance of manure gasification systems for non-poultry operations have also been reviewed and evaluated. A clearinghouse website for thermal manure-to-energy processes has been developed.

What have we learned?

The projects have shown that poultry litter can be used as a fuel source, but operation and maintenance issues can impact the performance and longevity of a thermal conversion system. These systems are still in the early stages of commercialization and modifications are likely as lessons are learned. Preliminary air emission data shows that most of the nitrogen in the poultry litter is converted to a non-reactive form. The other primary nutrients, phosphorus and potassium, are preserved in the ash or biochar co-products. Plant availability of nutrients in the ash or biochar varies between the different thermal conversion processes and ranges from 80 to 100 percent. The significant volume reduction and nutrient concentration show that thermal conversion processes can be effective in reducing water quality issues by lowering transportation and land application costs of excess manure phosphorus.

Future Plans

Monitoring will continue for the existing demonstration projects. Based on the lessons learned, additional demonstration sites will be pursued. As more manure-to-energy systems come on-line the clearinghouse will be updated. Based on data collected, NRCS conservation practice standards will be generated or updated as necessary.

Author

Jeffrey P. Porter, PE, Manure Management Team Leader, USDA-Natural Resources Conservation Service jeffrey.porter@gnb.usda.gov

Additional information

Thermal manure-to-energy clearinghouse website: http://lpelc.org/thermal-manure-to-energy-systems-for-farms/

Environmental Finance Center review of financing options for on-farm manure-to-energy including cost share funding contact information in the Chesapeake Bay region: http://efc.umd.edu/assets/m2e_ft_9-11-12_edited.pdf

Sustainable Chesapeake: http://www.susches.org

Farm Pilot Project Coordination: http://www.fppcinc.org

National Fish and Wildlife Foundation, Chesapeake Bay Stewardship Fund: http://www.nfwf.org/chesapeake/Pages/home.aspx

Acknowledgements

National Fish and Wildlife Foundation, Chesapeake Bay Funders Network, Farm Pilot Project Coordination, Inc., Sustainable Chesapeake, Flintrock Farm, Mark Weaver Farm, Mark Rohrer Farm, Riverview Farm, Wayne Combustion, Enginuity Energy, Coaltec Energy, Agricultural Waste Solutions, University of Maryland Center for Environmental Science, Environmental Finance Center, Virginia Cooperative Extension, Lancaster County Conservation District, Virginia Tech Eastern Shore Agricultural Research and Extension Center, Eastern Shore Resource Conservation and Development Council, with funding from the USDA Conservation Innovation Grant Program and the U.S. EPA Innovative Nutrient and Sediment Reduction Program.

March 5, 2019March 6, 2019

Nutrient Recovery Technologies—A Primer on Available and Emerging Nitrogen, Phosphorus, and Salt Recovery Approaches, their Performance and Cost

Purpose

This presentation highlights existing and emerging recovery technologies that can be combined with energy recovery from dairy manure. A variety of technologies is in development, specifically tailored for solids, phosphorus, nitrogen, salt and combinations thereof. Data regarding estimated performance and cost as well as summary graphs are presented. Attention is focused on in-series treatment with anaerobic digesters, but mention is given to incorporation with other renewable energy/fuel technologies.

What did we do?

The presentation focused on information from pilot and commercial demonstration of nutrient recovery (NR) technologies, with sources including literature, pilot reports, company literature, project feasibility studies, and interviews. This presentation attempts to identify broad approaches, identify strengths and weaknesses of those approaches, as well as specific situations where each might be most appropriate. Individual case studies have been included so as to offer more detailed information about representative technologies.

What have we learned?

This presentation estimated a range of performance and cost achievements for each of these broad approaches to NR. Ranges are not necessarily indicative of individual technologies but rather represent an approximate average based on best available data in conjunction with some assumptions. Several factors made these performance and cost estimates challenging. In some cases, technologies are already operating in the dairy sector at commercial scale. In many cases, technologies are operating at a pre-commercial scale, or are used commercially in other sectors such as wastewater treatment facilities. This required assumptions to be made based on informed estimates. Also, because technologies are often applied within a single manure management system, it is clear that costs would vary significantly if applied in other situations. For example, an NR technology that operates well on dilute flush manure would likely require pretreatment at additional cost if applied to scraped manure. Finally, limited data were available, particularly in regard to costs. This is mostly due to proprietary concerns or unwillingness to cite specific costs due to rapidly changing technologies. These factors mean that performance and cost ranges should be viewed as “best estimates” based on the data currently available to researchers. It is meant to provide a broad view of the industry as a whole, and should not be used for individual technology purchase or investment decisions.

Report Conclusion

Future Plans

There are many other factors that will be important in developing the path forward for the dairy industry with respect to nutrient recovery, form and function of recovered nutrient products for example. Ongoing development of dairy NR technologies should therefore aim to develop products that fit seamlessly into existing fertilizer delivery systems while providing a form that meets transportation and market needs, at price points that are competitive with synthetic fertilizers. Development within such a competitive environment requires not only a sustained effort, but also national and capable partners, a lesson that has been identified during development of a market for high-value peat moss replacement from AD.

A look at the bigger picture, using analytical tools such as life cycle analysis, is also important. Comparison of the performance capabilities and costs of these two approaches are one point of comparison, but a more in-depth comparison may also include consideration of resource management and sustainability, including features such as energy balance, greenhouse gases, and eco-system benefits.

Authors

Jingwei Ma, Research associate at Washington State University mjw@wsu.edu

Craig Frear, Assistant Professor at Washington State University, Georgine Yorgey, Research associate at Washington State University, Chad Kruger, Director at Washington State University Center for Sustaining Agriculture & Natural Resources (CSANR)

Additional information

http://csanr.wsu.edu/wp-content/uploads/2014/07/ICUSD-Emerging-NR-Technology-Report-Final.121113B.pdf

Acknowledgements

This research was supported by funding from USDA National Institute of Food and Agriculture, Contract #2012-6800219814; National Resources Conservation Service, Conservation Innovation Grants #69-3A75-10-152; Biomass Research Funds from the WSU Agricultural Research Center; the Washington State Department of Ecology, Waste 2 Resources Program; US Environmental Protection Agency Grant # RD-83556701; and the Water Environment Research Foundation.

March 5, 2019March 20, 2019

The Dairy Manure Biorefinery

Why Consider Additional Technologies with Anaerobic Digestion?

Some dairy farms have experimented with “add-on” technologies to enhance the value of the products generated from anaerobic digesters to improve economics and address other environmental and management concerns. This effort has intensified in recent years, as prices paid for electricity continue to fall. This trend is making it more difficult to justify the installation of new digesters or maintain active anaerobic digestion (AD) projects based on electricity sales alone.

What did we do?

Based on ten years of research and extension within the field of dairy digesters, we are proposing that the concept of a dairy manure biorefinery can be useful to focus ongoing research and commercialization efforts (Figure 1). A biorefinery integrates a core biomass conversion process (in this case, AD, converting manure and in many cases other organic substrates) with additional downstream technologies. These combined technologies generate multiple value-added products including fuels, electricity, chemicals, and other products (NREL, 2009). Most add-on technologies relevant to dairy facilities have been modified from technologies used in the wastewater treatment and oil and gas industries.

What have we learned?

Ongoing research and commercialization efforts by our team and others aim to:

Adapt technologies to fit the economic and other constraints of dairy digesters.
Increase efficiency and reduce costs by maximizing the complimentary nature of technologies (e.g. waste heat from one process is used in another process).

Specific add-on technologies that are continuing to evolve within the biorefinery context include:

Biogas Upgrading to remove impurities from biogas (primarily carbon dioxide, hydrogen sulfide, and water vapor).

Output: Purified biogas that can be used as a transportation fuel (e.g. liquefied natural gas) or injected directly into natural gas piplelines.

Additional social and economic benefits: Renewable fuel can reduce demand for fossil fuels, and can often receive economic credits (e.g. renewable identification numbers, low carbon fuel standard)

Fiber Upgrading to process the fiber that is removed from AD effluent.

Output: Upgraded fiber can be sold as a higher-value soil amendment in the horticultural industry

Additional social and economic benefits: Fiber can replace use of non-renewable resource (peat moss) by horticultural industry

Nutrient Recovery to strip nitrogen (N) and phosphorus (P) from anaerobic digester effluent.

Outputs: Soil amendment products that can be sold offsite where nutrients are needed

Additional social and economic benefits: Reductions in N and P applied to nearby fields, and reduced effluent hauling distances/costs for land application due to lower nutrient concentration in effluent

Water Recovery to generate “recycled” water using advanced technologies

Output: Water that can be used for animal drinking, or as dilution water for the AD facility

Additional social and economic benefits: Reduces consumption of fresh water, a limited resource, and reduces costs for land-application of AD effluent

Overall Potential Impact. Improving economics and addressing other critical issues for dairy producers (e.g. nutrient issues) has the potential to advance farm-based AD adoption significantly beyond its current 244 farms. It has been estimated that a mature bio-refinery industry based on AD on large U.S. dairy farms could create an estimated bio-economy of nearly $3 billion that complements the production of milk and dairy products (ICUSD, 2013).

Figure 1. Stepwise depiction of the process

Figure 2. Total likely value added by most likely scenario

Authors

Georgine Yorgey (presenting author)^a, Craig Frear^b, Nick Kennedy^a, Chad Kruger^a, Jingwei Ma^b, and Tara Zimmerman^a

^aCenter for Sustaining Agriculture and Natural Resources, Washington State University

^bDepartment of Biological Systems Engineering, Washington State University

Future Plans

An extension document describing this concept and the add-on technologies in additional detail is being prepared. This document is part of a series of extension documents on Dairy AD Systems, being prepared by the authors and other colleagues at Washington State University. In addition, ongoing work and collaborations by our team are seeking to investigate, evaluate, and improve individual technologies and the linkages amongst them.

Additional Information

ICUSD, 2013. National market value for anaerobic digestion products. Report to Innovation Center for US Dairy, August 2013.

Acknowledgements

This research was supported by USDA National Institute of Food and Agriculture, contract #2012-6800219814; and Biomass Research Funds from the Washington State University Agricultural Research Center.

March 5, 2019March 21, 2019

Economic Recovery of Nitrogen and Phosphorus from Anaerobic Digestate as Concentrated Ammonium Hydroxide and Hydroxyapatite

The paper describes the laboratory and pilot studies of an autotrophic fixed film reactor, the rotating photo-bioreactor (RPB), that reclaims concentrated ammonia and phosphorus from anaerobic digestate.

Why Recover Nutrients from Anaerobic Digestion?

All of the nitrogen and phosphorus present in an anaerobic digester’s influent can be found in the effluent digestate. However, during the digestion process the organic nitrogen is by and large converted to ammonia, and the organic phosphorus converted to soluble orthophosphate. The ammonia and phosphorus are normally discharged to holding ponds prior to field application. The pH increases in the holding ponds due to the loss of CO₂ resulting in a shift of the ammonium (NH₄⁺) to toxic ammonia gas (NH₃) that is subsequently lost to the atmosphere. Upon land application additional ammonia losses occur and dissolved orthophosphate leached.

Anaerobic digestion does not recover the nutrients as often claimed. Some of the nutrients accompanied by pathogens, hormones, and antibiotics are land applied to improve agricultural yields. The remaining nutrients are lost to the environment. Methods to reclaim ammonia are limited to high temperature ammonia stripping, or ion exchange with acid stripping of NH₃ to form dilute solutions of ammonium sulfate or ammonium nitrate. Those methods require chemical reactants and produce products having little economic value. Other options include recovery of a portion (< 15%) of the nitrogen and a majority of the orthophosphate found in digestate, with the addition of magnesium, as crystalline struvite (MgNH4PO4.6H2O). However, that process is expensive, requires reactants, removes only a portion of the nitrogen and may be inhibited by the presence of calcium in the digestate requiring acidification.

What Did We Do?

This work was performed to verify a process for recovering ammonia as a highly concentrated and valued ammonium hydroxide and the orthophosphate as solid hydroxyapatite. Based on both previous pilot investigations, and the work of others, the RPB process was expected to remove and recover 80% to 90% of the ammonia and phosphate without the addition of chemicals, at normal digestate temperatures, and ambient pressures. Products that had a value greater than the cost of recovery were expected to be produced. The process uses a single reactor containing concentrated phototrophic organisms (cyanobacteria) that consume the bicarbonate alkalinity of the substrate for growth and thereby raise the pH, shifting the digestate ammonium to ammonia gas that can be stripped at low temperatures. The high pH and low bicarbonate concentration used in ammonia recovery are also required for the precipitation of orthophosphate as calcium carbonate or hydroxyapatite. The removal and reclamation of both ammonia and phosphate require an elevated pH and low bicarbonate alkalinity produced by the cyanobacteria.

Three laboratory scale rotating photo bioreactors, shown in Figure 1, were constructed to verify the removal and recovery of ammonia as a highly concentrated ammonium hydroxide solution that could be sold as diesel exhaust fluid. The lab scale pilot used cyanobacteria to increase the solution pH and shift the ammonium to ammonia gas that was continuously removed by recycled air flowing over the plates. The bioreactors were operated at 3.5 RPM using different attached growth media, under different lighting (30 – 80 PAR) conditions, stripping gas flow rates, and Hydraulic Retention Times (HRT). Concentrated, turbid, anaerobic centrate, having an ammonia concentration between 1,000 and 2,400 mg/L, was utilized as the substrate.

What We Have Learned?

The laboratory scale pilot bioreactors were able to establish that carbon fiber was the best fixed film media from a variety of inorganic fabrics. The operation further established that the stripping gas flowing over the cyanobacteria growth plates was sufficient to strip essentially all of the ammonia gas and thus eliminate ammonia toxicity to the cyanobacteria. Light intensity controlled the cyanobacteria growth rates, and thus the pH of the solution. The optimum HRT is yet to be determined. The system is currently operating at a 6 hour HRT but the final value may be significantly lower. Concentrated (15%) ammonia is currently being recovered but the final values are expected to be greater.

Future Plans

This study investigated most of the variables associated with stripping and recovering ammonia from a turbid, highly concentrated, digestate using a fixed film autotrophic system. The optimum rotation rate was one of the few variables not thoroughly investigated. The results obtained have established the basis for the design and construction of a pilot facility that will reclaim ammonia as a valued diesel exhaust fluid for Selective Catalytic Reduction (SCR) of combustion NOx thus eliminating, the two primary sources of reactive nitrogen discharged to the environment. Future work will focus on removing and reclaiming sufficient quantities of ammonia as diesel exhaust fluid and testing the fluid in diesel engines that use SCR to remove exhaust NOx.

Author

Dennis A. Burke PE, CEO, Environmental Energy & Engineering Company; waeng@me.com

Nutrient Management aka, Nutrient Reclamation from all organic waste

March 5, 2019July 6, 2020

Ammonia Recovery from Livestock Wastewater with Gas Permeable Membranes

Waste to Worth home | More proceedings….

Why Study Ammonia Recovery from Livestock Wastewater?

This presentation shows a novel system that uses gas-permeable membranes to capture and recover ammonia from liquid manure, reducing ammonia emissions from livestock operations, and recovering concentrated liquid nitrogen that could be sold as fertilizer.

What Did We Do?

These systems use gas-permeable membranes as components of new processes to capture and recover the ammonia in liquid manures. The new process includes the passage of gaseous ammonia contained in the liquid manure through a microporous hydrophobic membrane and capture and concentration with circulating diluted acid on the other side of the membrane. The membranes can be assembled in modules or manifolds. For liquid manure applications, the membrane manifolds are submerged in the liquid and the ammonia is removed from the liquid manure in barn pits or storage tanks and lagoons before it goes into the air.

Cross-sectional diagram of ammonia capture using hydrophobic gas-permeable membrane. Ammonia gas (NH₃) in the liquid manure permeates through hydrophobic membrane walls with micron-sized pores, where it combines with the free protons (H⁺) in the acid solution to form non-volatile ammonium ions (NH₄⁺⁾.

What Have We Learned?

The concept was successfully tested using concentrated swine manure effluents containing 140 to 1,400 mg/L NH4-N. The use of gas-permeable membranes to remove ammonia from liquid manure was effective, and the rate of N recovery by the gas-permeable membrane system was higher with higher ammonia concentration in the manure. While ammonia gas passed readily through the membrane pores, the soluble COD compounds did not pass. An average removal rate from 45 to 153 milligrams of ammonia per liter per day was obtained when ammonia concentrations in swine lagoon liquid ranged from 138 to 302 milligrams ammonia per liter. The rate of ammonia recovery was also increased with increased pH of the wastewater. With a natural pH of 8.3, the rate of N recovery was about 1.2% per hour. This rate was increased 10 times (to 13% per hour) at pH of 10 after alkali addition. In another study, we immersed the membrane module into raw liquid manure that had 1,400 milligrams of ammonia per liter, and after 9 days, the total ammonia concentration decreased about 50 percent to 663 mg per liter. The gaseous ammonia in the liquid (or free ammonia) linked to ammonia emissions decreased 95 percent from 114.2 to 5.4 milligrams per liter. The same process was used in 10 consecutive batches of raw swine manure and ended up recovering concentrated nitrogen in a clear solution that contained 53,000 milligrams of ammonia per liter. The new technology could help change on-farm nitrogen management: Livestock producers could use the technology to help meet air-quality regulations, save fuel, protect the health of livestock and their human caretakers, improve livestock productivity, and recover concentrated liquid nitrogen that can be re-used in agriculture as a valued fertilizer.

Diagram of ammonia recovery system using with gas permeable membranes

Recovery and concentration of ammonia from liquid manure using gas-permeable membrane system. Diagram and pictures show prototype testing, using the same stripping solution with repeated batches of liquid manure.

Future Plans

On-farm demonstration studies will be conducted in 2013-2014 in cooperation with Dr. John Classen, North Carolina State University, through an NRCS Conservation Innovation Grant (CIG) awarded in FY2012 “Ammonia recovery from swine wastewater with selective membrane technology”. The project will demonstrate recovery of ammonia from liquid manure effluents using the gas-permeable technology in three different manure collection systems: under floor belt system, scraper system, and anaerobic digester.

USDA seeks a commercial partner to develop and market this invention (US Patent Appl. SN 13/164,363) http://www.ars.usda.gov/business/docs.htm?docid=763&page=5

Authors

Matias Vanotti, USDA-ARS, Florence, South Carolina, matias.vanotti@ars.usda.gov

Matias Vanotti, Ariel Szogi, Patrick Hunt

USDA-ARS, Coastal Plains Soil, Water, and Plant Research Center, Florence, SC

Additional Information

“Livestock Waste Management 2.0: Recycling Ammonia Emissions as Fertilizer“ published in the November/December 2012 issue of Agricultural Research magazine http://www.ars.usda.gov/is/AR/archive/nov12/livestock1112.htm

“Recovery of ammonia with gas permeable membranes” research update at USDA-ARS-CPSWPRC website http://www.ars.usda.gov/Research/docs.htm?docid=22883#ammonia

Vanotti, M.B., Szogi, A.A. 2010. “Removal and recovery of ammonia from liquid manure using gas-permeable membranes”. In: Proceedings of the 2010 American Society of Agricultural and Biological Engineers Annual International Meeting, June 20-23, 2010, Pittsburgh, Pennsylvania. 5 p. Paper No. 1008376.

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