The Farm Manure to Energy Initiative: Using Excess Manure to Generate Farm Income in the Chesapeake’s Phosphorus Hotspots

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Abstract

Currently, all the Bay states are working to achieve nutrient reduction goals from various pollution sources.  Significant reductions in phosphorus pollution from agriculture, particularly with respect to phosphorus losses from land application of manure are needed to support a healthy aquatic ecosystem.  Producers in high-density animal agricultural production areas such as Lancaster County region of Pennsylvania, the Delmarva Peninsula, and the Shenandoah Valley region of Virginia, need viable alternatives to local land application in order to meet nutrient reduction goals.

Field demonstrations will be monitored to determine whether the technologies are environmental beneficial, and economically and technically feasible. Specific measures of performance include: reliability and heat distribution, in-house air quality, avoided propane or electricity use, costs to install and maintain, fertilizer and economic value of ash or biochar produced, air emissions, and fate of poultry litter nutrients. Technology evaluation results will be shared on a clearinghouse website developed in partnership with eXtension.

The Farm Manure to Energy Initiative is also supporting efforts to develop markets for nutrient rich ash and biochar co-products. Field trials using nutrient rich ash and biochar from poultry litter thermochemical processes for fresh market vegetable production are currently underway at Virginia Tech’s Eastern Shore Agricultural Research and Experiment Station.

Purpose

The Farm Manure to Energy Initiative is a collaborative effort to evaluate the technical, environmental, and economic feasibility of farm-scale manure to energy technologies in an effort to expand management and revenue-generating opportunities for excess manure nutrients in concentrated animal production regions of the Chesapeake Bay watershed.

What Did We Do?

The project team went through a comprehensive review process and identified three farm-scale, manure to energy technologies that we think have the potential to generate new revenue streams and provide alternatives to local land application of excess manure nutrients.  Installation and performance evaluation of two of these technologies on four host farms in the Chesapeake Bay region are underway. Partners have also completed a survey of financing options for farm-scale technology deployment and published a comprehensive financing resources guide for farmers in the Chesapeake Bay region.

What Have We Learned?

To date, we have not identified any manure to energy technologies that also provide alternatives to local land application of excess manure nutrients for liquid manures.  Thermochemical manure to energy technologies using poultry litter as a fuel source seem to show the most promise for offering opportunities to export excess nutrients from phosphorus hotspots in the Chesapeake Bay region. Producing heat for poultry houses is the most readily available energy capture option.  We did not identify any vendors with a proven approach to producing electricity via farm-scale, thermochemical manure to energy technologies. With respect to the fate of poultry litter nutrients, preliminary air emissions data indicates that most poultry litter nitrogen (greater than 98%) is converted to non-reactive nitrogen in the thermochemical process. Phosphorus and potash are preserved in the ash or biochar coproducts. Preliminary field trial results indicate that phosphorus in ash and biochar is bioavailable and can be used as a replacement for commercial phosphorus fertilizer, but bioavailability varied according to the thermochemical process.

Future Plans

We are currenty in the process of installing and measuring the performance of farm-scale demonstrations in the Chesapeake Bay region.  We are collaborating with the Livestock and Poultry Environmental Learning Center to develop a clearinghouse website for thermochemical farm-scale manure to energy technologies that will be hosted on the eXtension website.  Performance data from our projects will be shared on this website, which can also be used as a platform to share information about the performance of other farm-scale, thermochemical technology installations around the U.S. Technical training events using farm demonstrations as an educational platform will be hosted during the later half of the project. Additional field and row crop trials to demonstrate the fertilizer value of the concentrated nutrient coproducts are also planned using ash from farm demonstrations.

Authors

Jane Corson-Lassiter, USDA NRCS, Jane.Lassiter@va.usda.gov; Kristen Hughes Evans, Executive Director, Sustainable Chesapeake

Additional partners in the Farm Manure to Energy Initiative include: Farm Pilot Project Coordination, Inc., University of Maryland Center for Environmental Studies, University of Maryland Environmental Finance Center, Virginia Cooperative Extension, Lancaster County Conservation District, the Virginia Tech Eastern Shore Agricultural Research and Extension Center, National Fish and Wildlife Foundation, Chesapeake Bay Funders Network, Chesapeake Bay Commission, and International Biochar Institute.

Additional Information

www.sustainablechesapeake.org

www.fppcinc.org

Acknowledgements

Funding for this project is provided by a grant from the USDA Conservation Innovation Grant program, the National Fish and Wildlife Foundation via the U.S. EPA Innovative Nutrient and Sediment Reduction Program, the Chesapeake Bay Funders Network, as well as technology vendors and host farmers participating in the technology demonstrations.

 

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. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Improving Methane Yields from Manure Solids through Pretreatment

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Abstract

This paper presents a description of the ABFX (Ammonium Bicarbonate Fiber Explosion) pretreatment process. The ABFX process is an extremely simple and inexpensive process that possesses the attributes of the Ammonia Fiber Explosion Process (AFEX) and CO2 explosion process while eliminating the cost associated with high temperature, high pressure and ammonia recovery. The process uses ammonia bicarbonate (ABC) recovered from anaerobic digestate to pretreat the substrate. The ABC is simply added to the substrate, pumped to a reactor, heated to temperatures less than 100°C, for a short duration. The pressure created by ABC volatilization is then released and the gases (CO2, NH3, H2O) condensed at ambient temperature to produce ABC that is then reused in the process. The process can operate with low temperature waste heat.

This paper presents a description of the process and the results of a National Science Foundation Small Business Innovative Research investigation that compared the methane gas yields from both pretreated and untreated grass silage and pretreated and untreated screened (screw press) dairy manure solids. The ABFX pretreated manure solids produced 38% more methane gas than the untreated while the ABFX pretreated grass silage produced 14% more methane gas than the untreated. The economic benefits of the process will be discussed.

Is There Potential to Improve Methane Yields from Manure?

A large fraction of municipal solid waste (MSW), crop residues, animal manures, forest residues, or dedicated energy crops are composed of lignocellulouse. Lignocellulosic substrates consist of a tightly woven matrix of cellulose, hemicellulose, and lignin polymers. Biological degradation of these polymers are carried out by a variety of enzymes. Pretreatment can enhance the bioconversion of the wastes or cop residues for ethanol or biogas production by increasing the accessibility of the enzymes to the substrate. Thus, pretreatment can increase the energy yield (biogas or ethanol) while decreasing the residual waste to be disposed.

Anaerobic bacteria easily convert the hemicellulose and amorphous cellulose to gas. However, conversion of the crystalline cellulose and lignin is far more difficult. Lignin is not converted to gas by anaerobic organisms. Only a fraction of the crystalline cellulose is converted to gas within the detention times commonly used (20 days) in anaerobic digestion. Pretreatment is required to rupture the crystalline cellulose for enzymatic hydrolysis. A wide variety of pretreatment technologies have been developed. Dilute acid pretreatment solubilizes the hemicellulose. Alkali, lime or sodium hydroxide pretreatment solubilize the lignin thus exposing the hemicellulose and cellulose for enzymatic attack. A variety of explosion processes such as steam, carbon dioxide, and liquid ammonia (AFEX) have also been developed that disrupt the crystalline cellulose and hemicellulose. Ammonia soaking, over prolonged periods of time, has also been used to pretreat straw for animal feed and thereby improve rumen digestibility and animal weight gain. All of the processes use high pressure and temperature, or toxic chemicals. The commonly used, conventional processes are not suitable for on-farm use.

What Did We Do?

Figure 1: ABFX Process

We substantiated the feasibility of a breakthrough pretreatment technology under a National Science Foundation Small Business Innovative Research (SBIR) grant that used the non-toxic Ammonium Bicarbonate (ABC) recovered from the anaerobic digestate. The pretreatment was accomplished with a simple device, shown in Figure 4, composed of a pump, that pumps the solid biomass substrate, mixed with a small amount of ABC, into a reactor. The reactor is closed and heated to temperatures below the boiling point of water. Once heated the ABC breaks down to its water, ammonia, and carbon dioxide components putting the contents under significant pressure. The pressure is then rapidly released causing the explosion or disruption of the lignocellulosic substrate and the breakdown of the crystalline cellulose. The gases (H2O, NH3, and CO2), are then condensed in a separate chamber to produce ABC that is reused in the next cycle. Nothing is wasted. The ABC is recovered and reused. The applied heat and detention time provided is sufficient to pasteurize the biomass and meet the temperature requirements of the downstream anaerobic reactor. It is a simple process composed of a solids pump, heat pump, and two low detention time (10± minutes) reactors.

The SBIR research consisted of pretreating both grass silage and concentrated, screw press, manure solids and digesting both pretreated and untreated silage and manure solids. The pretreated and untreated solids were digested in 10 reactors at a 12.5 day HRT and 35°C.

What Have We Learned?

Pretreatment of the grass silage increased the methane yield 16% over several months of operation. Pretreatment increased the methane yield from the pretreated manure solids by 35% over the same period. The increased gas yield was approximately equal to the methane yield from the crystalline cellulose present in the substrate that is normally not converted to gas. The research demonstrated the feasibility of pretreating lignocellulosic substrates in a simple, short detention time, low temperature process that does not dilute the substrate stream or use toxic chemicals such as liquid or gaseous ammonia, acids, or caustic.

Future Plans

The current plan is to build a prototype facility to pretreat a variety of crop residuals (corn stover, rice straw, wheat straw), dry feedlot manure and poultry litter.

Author

Dennis A. Burke, CEO, Environmental Energy & Engineering Company engineer@makingenergy.com

Additional Information

www.makingenergy.com

 

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. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.

Economical Recovery of Ammonia from Anaerobic Digestate

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Abstract

An economical process to capture residual ammonia nitrogen and reduce the production of new ammonia via the Haber process is needed. The CO2, N2O and NOx emissions from nitrification and denitrification of industrially created ammonia will be reduced as a result. The ammonia product should be sold at a profit, but less than $1,700 / ton N.

This paper describes the ABC process and presents the ammonia recovery and biomethane production results of a pilot investigation of the ABC process for the recovery of ammonia nitrogen. The work was supported by the US Department of Agriculture (USDA) under a Small Business Innovative Research project. The ABC process uses no chemicals and very little energy. The process recovers the ammonia as crystalline ammonium bicarbonate (ABC). In the process of producing the ABC, carbon dioxide is removed from the biogas to produce “biomethane”, a transportation quality fuel at little or no cost.

Figure 1 Pilot RPB without Cover.

Is It Possible to Recover Ammonia Economically?

The discharge of ammonia nitrogen is a well recognized adverse consequence of anaerobic waste treatment. As a result, further treatment to remove ammonia is required. A wide variety of processes have been developed to address the “ammonia issue”. The commonly used processes are the many variations of nitrification / denitrification and Anammox processes. The Anammox (anaerobic ammonium oxidation) process is the least expensive and produces significantly less GHG (N2O). The nitrification / denitrification and Anammox processes directly convert ammonia to nitrogen gas (N2) resulting in the loss of the ammonia resource at a treatment cost of approximately $1,600 / ton N for a large facility. The ammonia that is destroyed must be replenished through the Haber-Bosch process that requires 32 GJ of energy per ton of ammonia to produce and similar energy consumption to transport. The production and transport have a cost of $1,200 / ton N while producing substantial GHG emissions. The minimum total cost of destroying and replacing ammonia is greater than $2,800 / ton N. An economical process to capture residual ammonia nitrogen for reuse, while reducing the production of new ammonia via the Haber process, is needed. The CO2, N2O, and NOx emissions from nitrification and denitrification of industrially created ammonia will be reduced as a result.

A number of processes have been developed over the past 50 years to remove and recover ammonia as an ammonium sulfate or nitrate fertilizer. Several facilities were constructed in the EU in the 1970’s. Those facilities were however uneconomical because of the high cost of chemicals (acid, lime, sodium hydroxide) and sludge disposal. Modification of those processes that use ion exchange, as opposed to ammonia stripping, remain uneconomical since they also require caustic, salt, and sulphuric acid to remove ammonia and recover ammonium sulphate. An economical process that can recover ammonia as a solid product without the use of hazardous chemicals is required.

Figure 2 Ammonium Bicarbonate (ABC)

What Did We Do?

E3 developed the Ammonium Bicarbonate Recovery (ABCR) process that recovers the ammonia as a crystalline solid pathogen free, inorganic fertilizer without the use of any chemicals. In the process of producing the Ammonium Bicarbonate (ABC), carbon dioxide is removed from the biogas to produce “biomethane”, a transportation quality fuel at little or no cost. The products of the process are biomethane quality transportation fuel and solid ammonium bicarbonate fertilizer that can be used for the pretreatment of lignocellulosic substrates.

To overcome the ammonia reclamation process deficiencies, E3 developed the Rotating Photo Bioreactor (RPB) shown in Figure 1. The RPB is a horizontal ammonia stripping reactor that removes the ammonia without the use of any chemicals. An operating demonstration can be seen here

The stripped ammonia and water vapor are condensed to form a concentrated aqua ammonia solution. Turbid, ammonia laden, anaerobic digestate flows through a fixed film photo bioreactor, that uses natural and/or artificial light, to culture cyanobacteria that consume the bicarbonate in the digestate thus raising the pH to values exceeding 10. At the higher pH, the ionized ammonia (NH4+) is shifted to the gas form, NH3 that can be stripped by the low pressure gas flowing from the condensation unit over the upper portion of the rotating disks. Very little blower pressure is required. The impact of digestate turbidity is minimized by the thin liquid film flowing over the partially submerged rotating disks supporting the bicarbonate consuming cyanobacteria that require light. The ammonia laden gas is then returned to the condenser where the ammonia gas and water are condensed to recover concentrated aqua ammonia. The system operates at low liquid and gas pressures through the use of a heat pump and low pressure gas blower.

The aqua ammonia condensate is recovered when the effluent is being discharged from the digester. The condensate is stored in a tank for use throughout the day to clean the biogas by removing the carbon dioxide and hydrogen sulfide in the digester’s gas. The ammonia condensate is sprayed into the biogas stream where the ammonia and water react with the carbon dioxide to produce a solid ammonium bicarbonate precipitate that is removed, bagged, and stored as a renewable, low carbon footprint fertilizer to be applied to the fields when needed for crop growth or blended with the solid residuals to produce a balanced fertilizer.

What Have We Learned?

The pilot investigation substantiated that high BTU (990±) biomethane could be produced from biogas while recovering 85%± of the ammonia present in the digestate at less capital and O&M cost of producing electricity.

Future Plans

The current plan is to build a full scale operating facility treating high nitrogen content manure such as poultry manure.

Author

Dennis A. Burke, CEO, Environmental Energy & Engineering Company engineer@makingenergy.com

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. 2013. Title of presentation. Waste to Worth: Spreading Science and Solutions. Denver, CO. April 1-5, 2013. URL of this page. Accessed on: today’s date.