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Ammonia (NH3) Mitigation Using Electrolyzed Water Spray Scrubber

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Abstract

The objective of this research was to evaluate electrolyzed water as a solution for a lab-scale spray scrubber for removing NH3 from air. A one-stage spray scrubber was fabricated to treat 50 cfm (1.42 m3/min) of introduced mixed NH3-air with an approximate NH3 concentration of 20 ppm. The mixed air was blown, countercurrent, to the 5-ft vertical scrubber body using a fan. Eight scrubber design variables were studied including contact times, nozzle types and scrubber solutions. Three contact times were 0.3, 0.6 and 0.9 s.  The two narrow and standard nozzles sprinkled in a full-cone spray pattern but at different angles of 26ᴼ and 52ᴼ, respectively. The scrubber solutions variables tested were reverse osmosis (RO) water and two types of electrolyzed water (50 ppm of total chlorine) with pH = 9.0 and pH = 6.5. The 18 combinations of treatments were tested in three replications and statistically analyzed to investigate the objective. The result showed that all of the experiments were able to mitigate the NH3, but at different efficiencies. The maximum efficiency of 53% was acquired with the narrow nozzle, 0.9s contact time and electrolyzed water with pH = 6.5. Therefore, it was concluded that increasing the contact time, decreasing the pH of electrolyzed water and using the narrow angle, higher flow rate nozzle increased the scrubber efficiency.

Ammonia scrubbing experiments conducted in three replications

Why Study Ammonia Mitigation at Poultry Houses?

Ammonia (NH3) emissions from poultry houses are an environmental challenge because of the large volume of polluted ventilation air from the house’s exhaust fans. One idea for mitigation of NH3 was to developed and evaluate a lab-scale spray scrubber that used an electrolyzed water scrubber solution.

Lab-scale spray scrubber

What Did We Do?

A one-stage spray scrubber was fabricated to treat 50 cfm of mixed NH3-air with approximate NH3 concentration of 20 ppm. The mixed air was blown, countercurrent, to the 5-ft vertical scrubber body using a regular fan and implemented 8 variables including contact times, spray types and scrubber solutions. Three contact times for about 0.3, 0.6 and 0.9 second were applied by changing the elevation of the spray stage. Also, two types of spray nozzles were studied to determine the effect of droplet size and the spray flow rate. The nozzles sprinkled in the pattern of a full-cone spray but in different spray angles; narrow and standard with 26ᴼ and 52ᴼ spray angle, respectively. The applied scrubber solution variables were reverse osmosis (RO) water and two types of electrolyzed water (50 ppm of total chlorine) with pH = 9.0 and pH = 6.5. Thus, 18 scenarios conducted in three replications and statistically analyzed to investigate the objective.

What Have We Learned?

The results showed that the scrubber in all experiments was able to mitigate the NH3 with different efficiencies. The efficiencies were averaged among the replications. The maximum efficiency of 56% was acquired by the narrow nozzle, 0.9s contact time and electrolyzed water with pH = 6.5 scenario. Therefore, it was concluded that increasing the contact time, decreasing the pH of electrolyzed water and the type of nozzle had increased the efficiency of the scrubber.

Ammonia scrubbing experiments conducted in three replications

Future Plans

After the electrolyzed water scrubber design and operating ranges are better understood from these laboratory studies, this technology will then need to be demonstrated under field operating conditions.  Wet scrubbers designed based on knowledge gained from the laboratory studies can be placed in a trailer along with all necessary analysis equipment and moved to the site of an operating poultry building.  Findings from this research could also be applied to many other types of animal production facilities.

Authors

Gerald Riskowski, Professor, Biological & Agricultural Engineering Department, Texas A & M University, riskowski@tamu.edu

Amir M. Samani Majd, PhD candidate, Biological & Agricultural Engineering Department, Texas A & M University

Ahmad Kalbasi, Researcher, Biological & Agricultural Engineering Department, Texas A & M University

Saqib Mukhtar, Professor, Biological & Agricultural Engineering Department, Texas A & M University

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 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.

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Ammonia Mitigation and Capture as a Liquid Fertilizer from Manure Using Gas-Permeable Membrane

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Why Capture Ammonia Released from Animal Manure?

Excessive emissions of ammonia (NH3 ) from animal manure negatively impact the environment with potential to pollute air, soil and water, and produce malodors. The objective of this study was to assess NH3 mitigation from liquid dairy manure (LM) using tubular acid-filled gas-permeable membranes (GPM) in laboratory experiments; and, to evaluate the possibility of scaling up the NH3 mitigation system for use on AFOs.

Fig 1. Schematic diagram of NH3 capture and recovery set-up in laboratory experiments

What Did We Do?

Initially, a bench-scale study of NH3 capture and recovery system from LM using a sulfuric acid-filled (pH=0.36) tubular GPM system was conducted (Fig .1). Four LM chambers with different surface areas were used with a constant depth of LM in each chamber to investigate the effects of surface areas on NH3 diffusion through membrane. Then the acid was diluted to pH of 2 and higher and the experiments were repeated by using one chamber to assess how diluted acid may extract NH3 from LM. For improving the mitigation process, a pH controller and acid dosing system (Fig. 2) was used to keep the pH of diluted acid at a desired level. To test the performance of the scaled-up system under field condition (Fig. 3) a prototype of the optimized laboratory NH3 mitiagation system was constructed and run in a dairy lagoon. In all experiments, real time NH3 and pH measurements were made from acid solution and LM to compare extraction and recovery of NH3 under laboratory and field conditions.

Fig 2. Acid pH controller and acid dosing pump for improving NH3 mitigation system

What Have We Learned?

Laboratory studies showed that two GPM systems, one submerged below the LM surface and the other suspended above the LM surface, resulted in nearly 50% removal (diffusion) of NH3 from the LM in less than 20 days. Ammonia was captured in concentrated sulfuric acid (pH=0.36) as ammonium sulfate solution (by-product). The GPM system was capable of removing NH3 from the air above (headspace) the LM. Moreover, diluted sulfuric acid with pH 2 or higher could also extract NH3 from LM. Application of diluted acid was essential to decrease the risk of handling strong acids. Also, the automatic pH controlling and acid dosing system increased the efficiency of concentrating NH3 in the acid by about 50%. Doubling the flow rate of acid circulation in the GPM system increased the concentration of by-product by 10%. A pilot scale of the GPM mitigation system in a dairy lagoon showed its feasible to harvest NH3 from LM under field condition (Fig. 3).

Fig 3. Field-scale NH3 mitigation in progress

Future Plans

New experiments in laboratory and field are needed to further improve NH3 mitigation and capturing efficiencies of the GPM system by modifying concentrations of acidic solution, changing GPM tube dimensions and morphology, and increasing the acid solution circulation flow rate in the GPM tube.

Authors

Saqib Mukhtar, Professor,  Biological & Agricultural Engineering Department, Texas A & M University System, mukhtar@tamu.edu

Amir M. Samani Majd, PhD Candidate, Biological & Agricultural Engineering Department, Texas A & M University

Additional Information

1- An Investigation of Ammonia Extraction from Liquid Manure Using a Gas-Permeable Membrane. Available at: http://elibrary.asabe.org/azdez.asp?JID=5&AID=37764&CID=loui2011&T=2

2- Application of Diluted Sulfuric Acid for Manure Ammonia Extraction Using a Gas-Permeable Membrane. Available at: http://elibrary.asabe.org/azdez.asp?JID=5&AID=42102&CID=dall2012&T=2

3- AFO Ammonia Mitigation Technology for Sustainable Environmental Stewardship

http://bt.e-ditionsbyfry.com/article/Ammonia+Mitigation+Technology+for+Sustainable+Environmental+Stewardship/1118439/118823/article.html

Acknowledgements

Funding for this study was provided through a grant by the United States Department of Agriculture: National Institute for Food and Agriculture (UDSA- NIFA).

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.

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Liquid Manure Storage Treatment Options, Including Lagoons

A vital component of liquid livestock and poultry manure collection and handling systems is storage capacity for the collected manure and associated material(flush water, wasted feed, etc.). This manure storage capacity is typically in the form of under-floor pits or outside storage tanks or ponds and/or treatment lagoons. These structures accumulate collected wastes and allow the waste management system operator to move away from a “daily scrape (collect) and haul” situation. This reduces time and labor needed for final disposition (either land application or off-farm “value-added” processing) of these manure accumulations.

What Is a Liquid Manure System?

“Liquid” livestock manure collection and handling systems are actually “fluid” livestock manure collection and handling systems. These systems are selected based upon the consistency or “thickness” of the manure and its flow characteristics. Manure flow characteristics are highly dependent on “solids content” or “percent solids” of the manure volume.

Liquid manure storage volume size depends on the amount of time in a year that is not available for land application or other manure utilization strategies. This is the design storage period. Land application time depends on growing season of the target crop(s) and local weather. Manure storage volume should be emptied by the end of the design storage period to be able to hold the expected amount of manure accumulation during the next storage period.

Earthen storage structure with artificial liner (from Proper Lagoon Management to Reduce Odor and Excessive Sludge Accumulation).

This web page deals with two general categories of liquid systems:

  • Pits or slurry systems for storage only
  • Lagoons with both slurry/wastewater storage and treatment (see National Center White Paper summary, Manure Management Strategies).

Types of Manure

“As-excreted” livestock manure moisture content changes as it moves through the collection process into storage. Liquid collection and handling systems add waste drinking water, wash water, flush water, rain, and stormwater runoff, lowering solids content below the 15% level typically used to define “solid” manure. A manure volume of 5 to 15% solids is “slurry” manure, with consistency and flow characteristics similar to thick chocolate malt. Manure volumes with 0 to 5% solids content have consistency and flow characteristics similar to water.

What Is the Difference Between Storage and Storage With Treatment?

Contrasting storage and storage w/treatment, a manure containment structure which is emptied at the end of the storage period is essentially a storage structure. A lagoon has storage volume but will also have a permanent pool for residual treatment volume that provides a bacterial seed bed for continual bacterial action at an elevated level. This permanent pool is not considered in the design of a structure used for storage alone. Essentially whatever goes into a properly managed storage structure is what is pumped out. A lagoon, however, is designed to promote decomposition of organic matter entering the lagoon. For this reason, a lagoon is much larger than a storage pond.

Management of Lagoons

A manure containment structure which is not emptied at the end of the storage period is being operated as a lagoon, whether designed that way or not. Storage operated in this manner becomes a smelly, overloaded lagoon. Generally, when agitation is used to put settled or floating solids into suspension before pumping out the effluent, or the slurry, the structure is being operated as storage.

Digested solids do accumulate in a lagoon and should be removed once every ten or more years, or as specified by the system design to restore residual treatment volume. In rare circumstances, particular to specific lagoons approaching this restoration point, some engineers recommend some agitation during normal pumpout to remove some of this accumulation. Routine pumping from the storage volume portion of a lagoon involves only wastewater (<5% solids) and requires no agitation.

Related Web Pages

Recommended Educational Resources

National Center for Manure and Animal Waste Management white paper summary, Manure Management Strategies published by North Carolina State University. A two page Executive Summary is available. The full white paper can be ordered from Midwest Plan Service, Iowa State University.

Page Managers: Ted Tyson, Auburn University, tysontw@auburn.edu and Saqib Mukhtar, Texas A&M University, mukhtar@tamu.edu .

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Role of Solid Liquid Separation in Manure Storage

There are benefits for manure storage systems in separating manure into solid and liquid components. Solid-liquid manure separation is also a desirable first step in many systems used for manure treatment (composting, anaerobic digestion, etc.)

Solids Accumulation

Waste solids, particularly those from dairy freestall housing bedding, can accumulate quickly in waste storage ponds. Solids accumulation requires longer, more thorough agitation at pump out time to re-suspend settled solids and special manure solids handling “chopper” pumps for transfer to tanker wagons or waste slurry irrigation systems.

Solids can cause pumping problems, and over time can greatly reduce usable storage pond volume. Serious consideration is usually given to the installation of solids separation equipment between animal housing, particularly dairy freestall barns, and the waste storage pond.

Mechanical separators are typically either rotating or stationary screens and generally remove 20 to 30 percent of the waste solids. These separators require little attention although operation in freezing weather requires special considerations. They produce manure solids that may be easily recycled as bedding or land applied off-farm with solid manure spreaders.

vibrating screen separator conveyor inclined screen separator typical two-cell settling basin

Settling Basins

Properly designed gravity settling basins can remove up to 50 percent of the waste solids but need enough elevation between the barn collection channel bottom and the maximum storage pond liquid surface height for installation of the settling basin and associated minimum 1% slope gravity in/out transfer lines. Gravity settling basins require periodic cleaning out with a tractor front end loader and work best when at least two are constructed side by side to allow alternating use and some manure solids drying out before cleaning.

Separated solids can be handled by conventional manure solids handling equipment. These nutrient-rich solids can be spread on distant fields and pastures as fertilizer and soil amendments, or sold for horticultural uses, with or without composting. Removing solids that retain their nutrients can help reduce nutrient loading on nearby fields, which are often irrigated from storage ponds or lagoons during the periodic pump outs required for proper management.

Related Web Pages

Page Managers: Ted Tyson, Auburn University, tysontw@auburn.edu and Saqib Mukhtar, Texas A&M University, mukhtar@tamu.edu .

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Livestock Mortality Composting – Beyond the Basics Part 1

The topics for this webcast include: pile characteristics for effective composting, management and environmental considerations when siting and managing composting facilities; mortality compost nutrients for on-farm use; and teaching the benefits of mortality composting to producers. This presentation was originally broadcast on August 15, 2014. More… Continue reading “Livestock Mortality Composting – Beyond the Basics Part 1”

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