Animal feeding operations emit gases and particulate matter (PM). The gases and PM emissions can negatively impact the environment and human and animal health locally, regionally, and globally. Some gases are odorous, some, including ammonia and hydrogen sulfide, can be hazardous; others like carbon dioxide, methane, and nitrous oxide are greenhouse gases. Some gases react with other chemicals in the atmosphere to produce fine particulates that contribute to respiratory diseases, haze and impaired visibility. This fact sheet describes the use of wet scrubbers to remove potentially harmful gases from the air exhausted from barns housing livestock or poultry. For more, see: http://www.extension.org/pages/62145/wet-scrubbers-curriculum-aqeaa-mit
It deals with biological water quality improvement through disinfection, disinfectants and disinfection kinetics, chlorine and other commonly used disinfectants, breakpoint chlorination and chlorination system
DEL Ozone secondary disinfection systems for commercial pools meet Model Aquatics Health Care (MAHC) guidelines. The MAHC is an emerging comprehensive set of best practices for public pool and aquatics operators.
It deals with biological water quality improvement through disinfection, disinfectants and disinfection kinetics, chlorine and other commonly used disinfectants, breakpoint chlorination and chlorination system
DEL Ozone secondary disinfection systems for commercial pools meet Model Aquatics Health Care (MAHC) guidelines. The MAHC is an emerging comprehensive set of best practices for public pool and aquatics operators.
Legislation preventing the discharge of untreated waste overboard has been in place for some time with a requirement that it should be retrofitted where not already in use.
Sewage treatment plant on a ship explainedLee Adrian
Discarding sewage produced onboard on a ship is one of the few tasks on a ship which should be taken utmost care of if one wants to same him and his shipping company from heavy fine. The sewage generated on the ship cannot be stored on the ship for a very long time and it for this reason it has to be discharged into the sea.
internship report on performance of sewage treatment plantAshok Devasani
the report presents a clear description about the performance of 30 MLD sewage treatment plant located in the vicinity of Hyderabad. it also provides a general information of the different sewage treatment process
DESIGN OF A 30 MLD SEWAGE TREATMENT PLANT(PROJECT REPORT) Ratnesh Kushwaha
This is a project report on design of a 30 MLD sewage treatment plant. It includes the different characteristics of waste water, various treatment units, design calculations and a layout of sewage treatment plant. This report also includes the future scope of this project.
Visit my slide share channel for downloading power point presentation of this project
Raw water should be treated to make it potable/fit for drinking. So a line of treatments should be followed to treat the water. After Coagulation and sedimentation the process of filtration and disinfection are followed.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Effective Techniques to control gaseous & particulate pollutionShristi Soni
This powerpoint has been made in context to briefly describe about the congtrol methods for gaseous and particulate pollution. This Presentation also briefly describes about the control devices seperately for Gaseous pollution as well as Particulate Pollution.
Hence, this PPT can be very effective way of studying and analysing this Topic
Legislation preventing the discharge of untreated waste overboard has been in place for some time with a requirement that it should be retrofitted where not already in use.
Sewage treatment plant on a ship explainedLee Adrian
Discarding sewage produced onboard on a ship is one of the few tasks on a ship which should be taken utmost care of if one wants to same him and his shipping company from heavy fine. The sewage generated on the ship cannot be stored on the ship for a very long time and it for this reason it has to be discharged into the sea.
internship report on performance of sewage treatment plantAshok Devasani
the report presents a clear description about the performance of 30 MLD sewage treatment plant located in the vicinity of Hyderabad. it also provides a general information of the different sewage treatment process
DESIGN OF A 30 MLD SEWAGE TREATMENT PLANT(PROJECT REPORT) Ratnesh Kushwaha
This is a project report on design of a 30 MLD sewage treatment plant. It includes the different characteristics of waste water, various treatment units, design calculations and a layout of sewage treatment plant. This report also includes the future scope of this project.
Visit my slide share channel for downloading power point presentation of this project
Raw water should be treated to make it potable/fit for drinking. So a line of treatments should be followed to treat the water. After Coagulation and sedimentation the process of filtration and disinfection are followed.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Effective Techniques to control gaseous & particulate pollutionShristi Soni
This powerpoint has been made in context to briefly describe about the congtrol methods for gaseous and particulate pollution. This Presentation also briefly describes about the control devices seperately for Gaseous pollution as well as Particulate Pollution.
Hence, this PPT can be very effective way of studying and analysing this Topic
Everyone can raise a question that how to prevent an Air pollution and so on. So here is our presentation on Control of Air pollution. So using the technique called adsorption sampling is an interesting one to all of the human beings
Waterman Engineers Australia offers scrubbers for controlling air pollution, which are used in industrial operations to remove dangerous pollutants such as sulfur dioxide, nitrogen oxides, and particulate matter from exhaust gases before releasing them into the atmosphere. The most common types of scrubbers are wet scrubbers, dry scrubbers, and electrostatic precipitators. Flue gas desulfurization (FGD) scrubbers are wet scrubbers used to remove sulfur dioxide from industrial and power plant flue gases. Packed tower gas scrubbers and packaged scrubbers are also effective at removing a wide range of pollutants. However, scrubbers produce trash that requires proper disposal and require energy to operate. Using scrubbers in conjunction with other strategies like pollution prevention and source reduction can help reduce emissions to the minimum.
Waterman Engineers Australia offers scrubbers for controlling air pollution, which are used in industrial operations to remove dangerous pollutants such as sulfur dioxide, nitrogen oxides, and particulate matter from exhaust gases before releasing them into the atmosphere. The most common types of scrubbers are wet scrubbers, dry scrubbers, and electrostatic precipitators. Flue gas desulfurization (FGD) scrubbers are wet scrubbers used to remove sulfur dioxide from industrial and power plant flue gases. Packed tower gas scrubbers and packaged scrubbers are also effective at removing a wide range of pollutants. However, scrubbers produce trash that requires proper disposal and require energy to operate. Using scrubbers in conjunction with other strategies like pollution prevention and source reduction can help reduce emissions to the minimum.
Biotechnology in Microbiology- includes the how microbial associations are worked out in secondary treatment techniques like activated sludge process, trickling filters, rotating biological contractors, composting, bioremediation etc.
“Study The Different Parameters of Sewage Treatment With UASB & SBR Technolog...IOSR Journals
Abstract: Every community produces both liquid and solid wastes and air emissions. The liquid wastewastewater-is
essentially the water supply of the community after it has been used in a variety of applications.
From the standpoint of sources of generation, wastewater may be defined as a combination of the liquid or
water-carried wastes removed from residences, institutions, commercial and industrial establishments, together
with such groundwater, surfacewater and stromwater as may be present. This waste water through sewer comes
to the sewage treatment plant so that parameters are reduced and treated wastewater be disposed into water or
land. For treating the sewage UASB( UP FLOW ANAEROBIC SLUDGE BLANKET) and SBR(SEQUENCING
BATCH REACTOR) technologies are mostly used.
All the parameters of these samples were analyzed using standard methods prescribed in “Standard methods for
examination of water and wastewater”. It was observed that pH & temperature values at outlet by both the
processes are almost same. Reading were taking on two consecutive days and value of Biochemical Oxygen
Demand by UASB process was 32, 32mg/l and by SBR process was 11, 16mg/l. Chemical oxygen Demand by
UASB process was 112, 96mg/l and by SBR process was 32, 34mg/l. Total Suspended Solids by UASB process
was 58, 44mg/l and by SBR process was 10, 12mg/l. Both the processes were used for treating the wastewater
and the SBR process showed better results as comparative to UASB.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Animal agriculture adaptation planning guide (climate change)LPE Learning Center
This 44-page publication produced by the AACC project is a planning guide to help guide farmers through the process of future farm planning considering climate change.
Format: Factsheet or Publication - Reference: Schmidt, D., E. Whitefield, D. Smith. 2014. Produced for Animal Agriculture in a Changing Climate Project.
What is the difference when talking about weather versus climate? How do you measure and describe the atmosphere? How are models used in predicting weather or climate? For more on this topic, visit: http://extension.org/60702
What are some of the basic principles and terminology involved in climate change? Learn more about the Earth's atmosphere, energy balance, and how the greenhouse effect can alter both climate and weather. What is climate forcing? What is climate feedback? For more on this topic, visit: http://extension.org/60702
The current state of cap-and-trade in the U.S. and the mandatory greenhouse g...LPE Learning Center
Where is U.S. policy and voluntary markets current at in terms of cap-and-trade? What is the mandatory greenhouse gas reporting rule and how does it apply to animal agriculture? For more on this topic, visit: http://extension.org/60702
Mitigation of greenhouse gas emissions in animal agricultureLPE Learning Center
What steps can animal agriculture take to reduce (mitigate) the greenhouse gas emissions from their farms? What is carbon sequestration and how will that play a role? For more on this topic, visit: http://extension.org/60702
Contribution of greenhouse gas emissions: animal agriculture in perspectiveLPE Learning Center
What are the emissions of relevant greenhouse gases from animal agriculture production and how does that compare to other industries? For more on this topic, visit: http://extension.org/60702
User capabilities and next generation phosphorus (p) indicesLPE Learning Center
Full proceedings available at: http://www.extension.org/72814
The phosphorus (P) index is the primary approach to identify field management strategies and/or manure application strategies likely to lead to excessive risk of P loss. It has been over 40 years since the first research connecting agronomic P management and water quality and over 20 years since the initial publication defining a P Index. This session will consider opportunities to build on and expand existing P Index strategies to make them more effective at protecting water quality and friendlier to the target user.
Full proceedings available at: http://www.extension.org/72818
Phosphorus indices provide relative loss ratings that then have a corresponding management response. Because most state Phosphorus Indices are qualitative it is not clear how the relative loss rating corresponds to actual phosphorus inputs into the receiving water and how the receiving water would react to these additions. Even with qualitative Phosphorus Indices, unless the water resource has a specific Total Maximum Daily Load, it is not clear how losses correspond to water quality outcomes. These issues will be discussed in the context of the 590 Natural Resources Conservation Standard for nutrient management.
Full proceedings available at: http://www.extension.org/72868
There has been a tremendous amount of activity and funding of conservation programs with regional and watershed-specific cost-share initiatives. While there have been some successes, water quality response in many areas has not been as great as expected. This has led many to question the efficacy of these measures and to call for stricter land and nutrient management strategies. In many cases, this limited response has been due to the legacies of past management activities, where sinks and stores of phosphorus along the land-freshwater continuum mask the effects of reductions in edge-of-field losses of phosphorus.
Estimation of phosphorus loss from agricultural land in the southern region o...LPE Learning Center
Full Proceedings is available at: http://www.extension.org/72817
The purpose of our work was to determine, within the southern region (AL, AR, FL, GA, KY, LA, MS, NC, OK, SC, TN, and TX), the feasibility of using different models to determine potential phosphorus loss from agricultural fields in lieu of phosphorus indices.
Estimation of phosphorus loss from agricultural land in the heartland region ...LPE Learning Center
Full Proceedings is available at: http://www.extension.org/72813
Phosphorus (P) indices are a key tool to minimize P loss from agricultural fields but there is insufficient water quality data to fully test them. Our goal is to use the Agricultural Policy/Environmental eXtender Model (APEX), calibrated with existing edge-of-field runoff data, to refine P indices and demonstrate their utility as a field assessment tool capable of protecting water quality. In this phase of the project our goal is to use existing small-watershed data from the Heartland Region (IA, KS, MO and NE) to determine the level of calibration needed for APEX before using the model to generate estimates of P loads appropriate for evaluating a P Index.
Checking ambition with reality the pros and cons of different approaches to s...LPE Learning Center
Full proceedings available at: http://www.extension.org/72793
The revision of the USDA-NRCS national standard for nutrient management in 2011 was driven, in part, by inconsistencies in state phosphorus (P) indices, rekindling debates over standardizing indices at regional or national scales. Reasonable arguments exist for maintaining the status quo, which allows for state specific site assessment approaches, as well as for regional and national P Indices, which would take advantage of expertise, resources and technologies that may not exist locally. In addition, a diversity of site assessment approaches have now been proposed that differ from the original P Index. Understanding the benefits and limitations provided with these approaches is key to advancing site assessment for P management.
Removing phosphorus from drainage water the phosphorus removal structureLPE Learning Center
Full proceedings available at: http://www.extension.org/72839
We constructed a phosphorus (P) removal structure on a poultry farm in Eastern OK; this is a BMP that can remove dissolved P loading in the short term until soil legacy P concentrations decrease below levels of environmental concern. A P removal structure contains P sorbing materials (PSMs) and are placed in a location to intercept runoff or subsurface drainage with high dissolved P concentrations. As high P water flows through the PSMs, dissolved P is sorbed onto the materials by several potential mechanisms, allowing low P water to exit the structure. While they vary in form, P removal structures contain three main elements: 1) use of a filter material that has a high affinity for P, 2) containment of the material, and 3) the ability to remove that material and replace it after it becomes saturated with P and is no longer effective.
Legacy phosphorus in calcareous soils effects of long term poultry litter app...LPE Learning Center
Full proceedings available at: http://www.extension.org/72864
Livestock manures, including poultry litter, are often applied to soil as crop fertilizer or as a disposal mechanism near livestock housing. Manures can improve soil quality and fertility; however, over-application can result in negative environmental consequences, such as eutrophication of surface waters following runoff of soluble or particulate-associate phosphorus (P). In soil, P exists in many forms (inorganic/organic, labile/stable) and the fate of manure P is highly dependent upon soil properties, including soil texture and microbial activity. The Houston Black series is a calcareous (~17% calcium carbonate), high-clay soil that occupies roughly 12.6 million acres in east-central Texas. These Blackland vertizols are agronomically important for the production of cotton, corn, hay, and other crops, but their high calcium and clay content could lead to accumulation of P in forms that are not readily available for plant utilization. Accumulated P could serve as a source of legacy P if mineralized or otherwise transformed in situ or transported with soil particles in runoff.
Identify and synthesize methods to refine phosphorus indices from three regio...LPE Learning Center
The full proceedings paper is at: http://www.extension.org/72867
This project was started to work with regional CIG projects to calibrate and harmonize Phosphorus Indices across the U.S., demonstrate their accuracy in identifying the magnitude and extent of phosphorus loss risk, and provide suggestions to refine or improve existing Indices. This research is important to provide consistency among state Phosphorus Indices and their subsequent recommendations.
Modeling phosphorus runoff in the chesapeake bay region to test the phosphoru...LPE Learning Center
Full Proceedings available at: http://www.extension.org/72795
The revision of USDA-NRCS’s standard for nutrient management coincided with significant assessment of the performance of Phosphorus (P) Indices in the six states that are tied to the Chesapeake Bay watershed. The 64,000 square mile watershed is the focus of unprecedented activity around nutrient management as a result of a 2011 Total Maximum Daily Load for P, nitrogen (N), and sediment under the Clean Water Act. In addition, the state of Maryland had required updates to it’s original P Index, resulting in broad scrutiny by various interest groups. Within this setting, USDA-NRCS funded a multi-state project to help advance the testing and harmonization of P-based management in the Chesapeake region.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Ethnobotany and Ethnopharmacology:
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New development in herbals,
Bio-prospecting tools for drug discovery,
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Reverse Pharmacology.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
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The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
We all have good and bad thoughts from time to time and situation to situation. We are bombarded daily with spiraling thoughts(both negative and positive) creating all-consuming feel , making us difficult to manage with associated suffering. Good thoughts are like our Mob Signal (Positive thought) amidst noise(negative thought) in the atmosphere. Negative thoughts like noise outweigh positive thoughts. These thoughts often create unwanted confusion, trouble, stress and frustration in our mind as well as chaos in our physical world. Negative thoughts are also known as “distorted thinking”.
Wetscrubbers for Mechanically Ventilated Animal Facilities
1. AIR QUALITY
Wet Scrubbers for Mechanically Ventilated
Animal Facilities
Mitigation Strategies: Wet Scrubbers
AIR QUALITY EDUCATION IN ANIMAL AGRICULTURE November 2011
Roderick B. Manuzun, Research Associate
Lingying Zhao, Associate Professor
A nimal feeding operations (AFO) emit gases and particulate matter (PM). The
gases and PM emissions can negatively impact the environment and human and
Food, Agricultural and Biological animal health locally, regionally, and globally. Some gases are odorous; some, includ-
Engineering ing ammonia (NH3) and hydrogen sulfide (H2S), can be hazardous; others like carbon
The Ohio State University dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are greenhouse gases. Some
Allison Jonjak, Graduate Research gases react with other chemicals in the atmosphere to produce fine particulates that
Assistant contribute to respiratory distress, haze, and impaired visibility.
Biological Systems Engineering
University of Nebraska–Lincoln Many AFOs use mechanically ventilated buildings to house animals safely, com-
fortably, and economically. Many mechanically ventilated AFO buildings have exhaust
fans that create a negative pressure in the building, which draws fresh outdoor air in
This publication provides an over- through planned inlets to replace the exhausted air. The air being exhausted contains
view of wet scrubbers and their use gases and PM.
to treat exhaust air from mechani- Wet scrubbers can be used to reduce gas and PM emissions from exhaust air of
cally ventilated livestock and poultry mechanically ventilated animal facilities and manure storage units. Scrubbers can be
installed directly to the exhaust fan outlet so that air leaving the building flows through
facilities.
the scrubber, where gases and PM are trapped by the scrubber.
Contents Wet scrubbers use a liquid, usually water-based, to remove gases and PM by
absorbing them onto wet surfaces or into liquid droplets or films. The liquid with the
Introduction.............................1 captured gases and PM needs to be handled properly to avoid polluting water, soil, and
air. Well-designed and managed wet scrubbers can be very effective. Scrubbers can
Design Factors.........................2 remove 50-99 percent of volatile organic compounds (VOC) and PM in air, and 90-99
Cost.........................................4 percent of oxides of nitrogen (NOx), sulfur oxides (SOx), H2S, and other inorganic gases
and vapors. Wet scrubbers can remove both PM and gases, but suitable operational
Limitations...............................5 conditions are needed.
References..............................6
Wet Scrubber Working Principles
Wet scrubbers clean air by physically trapping PM on wet surfaces and absorbing
gases into the liquid. In some cases, the gases react with chemicals in the liquid, too.
Small liquid droplets are more effective per unit volume of scrubber liquid because
they have more surface area than fewer, larger droplets. Very small liquid droplets,
however, are difficult to remove from the airstream after they absorb or react with the
gases.
PM is collected by physically impacting the PM into droplets or onto wet surfaces.
eXtension
PM is impacted on droplets or wet surfaces in different ways, depending on the scrub-
Air Quality in Animal Agriculture ber type used.
http://www.extension.org/pages/
15538/air-quality-in-animal-agriculture Spray scrubbers use liquid droplets to capture PM when it “sticks” to the liquid.
Droplets and PM are removed from the airstream as wastewater that needs to be
treated.
In packed column scrubbers, the moist packing material captures PM when it
adheres to the wet packing surfaces. Periodically packed column scrubbers are flushed
with water to remove PM collected on the surface of packing material. The flush water
is treated as a wastewater, which must be collected and handled properly. PM removal
efficiency of a wet scrubber depends on the PM-laden air volume, scrubbing liquid
1
2. flow rates, PM and liquid droplet velocities, and the retention time of the PM-laden air
in the scrubber.
Gases are removed by absorbing the gases into the liquid, typically water. Gas
solubility, which describes how easily a gas is absorbed in the scrubbing liquid, de-
pends on gas concentration gradients, chemical compatibility, reactivity between gas
and liquid phases, liquid temperature, pH, and contact time. Gases such as CO2, CH4,
and other VOCs are not readily captured by water alone due to their low solubility at
Animal feeding ambient conditions. NH3 is absorbed in water at low (acidic) pH, while H2S is absorbed
operations in water at high (basic) pH. If both NH3 and H2S or similar gases need to be removed
from the air, two separate wet scrubbing stages are needed to absorb the respective
emit gases and gases. The main drawbacks to adding either an acid or base to the scrubbing water
include additional chemical costs, increased corrosion potential, and difficulties with
particulate matter, handling chemicals safely. Plain water and a very long contact time is an option, but it
requires a larger scrubber. Gas absorption depends on the air and liquid flow rates, air
which can have a retention time, and droplet size and distribution.
negative impact on
Wet Scrubber Design Factors
the environment and
Wet scrubber type and size depend on the gas and PM concentrations and the
human and animal amount of exhaust air to be treated, which depends on species, number, and size of
animals housed. Scrubbers need to be sized to handle the maximum exhaust airflow
health locally, rate. Scrubbers need to effectively remove air pollutants and efficiently use water,
regionally, and space, and power. Standard wet scrubber design tools are still being developed.
globally. Four main characteristics affect scrubber effectiveness: flow configuration, scrub-
bing liquid composition, liquid-to-air ratio, and retention time.
Flow Configurations
Flow configuration influences retention time and the likelihood of scrubber plug-
ging. Three flow configurations (Figure 1) are commonly used in wet scrubbers: cross-
flow, counter-current-flow, and concurrent flow. The configurations determine how the
liquid and air flow interact with each other.
In cross-flow scrubbers (Figure 1a), the exhaust air flows at right angles to the
scrubber liquid flow. The retention time in cross-flow wet scrubbers is shorter than the
other configurations. Cross-flow is quite acceptable in most scrubber types.
In counter-current-flow scrubbers (Figure 1b), the scrubbing liquid flows in the op-
posite direction of the airflow.
The cleanest scrubbing liquid enters across from the cleanest air leaving the
scrubber. The dirtiest scrubbing liquid leaves the scrubber across from the dirtiest air
entering the scrubber. While counter-current flow is theoretically the best configuration
Clean
Liquid Liquid air Liquid Dirty
in in in air
Dirty Clean air
air A B C
Liquid Liquid Dirty Liquid Clean
out out air out air
Figure 1. Flow configurations for operating scrubbers: (A) cross, (B)
counter-current, and (C) concurrent.
2 AIR QUALITY EDUCATION IN ANIMAL AGRICULTURE Mitigation Strategies: Wet Scrubbers
3. for gas absorption, counter-current is usually only recommended for packed bed opera-
tion because of plugging concerns.
In concurrent-flow scrubbers (Figure 1c), the exhaust ventilation air and the scrub-
bing fluid travel in the same direction. The cleanest scrubbing liquid enters across from
the dirtiest air leaving the building. The dirtiest scrubbing liquid leaves the scrubber
across from the cleanest air leaving the scrubber. The gas absorption diminishes with
scrubber length, so concurrent flow requires the longest contact time of the three flow
configurations. Because concurrent flow minimizes plugging, it is recommended for
most PM applications in spite of the long contact time.
Scrubbing Liquid Composition
Scrubbing liquid choice is influenced by its concentration and the pollutants to
be removed from the air. The scrubbing liquid can be water, water with either an acid
added to enhance NH3 absorption, or a base added to enhance H2S absorption. Gas
solubility and reactivity in the scrubbing liquid impact gas absorption and are depen-
dent on ambient temperature. Water can remove many gases emitted from livestock
facilities.
An acidic solution (pH lower than 7) can be used to capture and retain NH3.
Sulfuric acid is commonly used because of its relatively low cost, and the ammonium
sulfate byproduct has fertilizer value.
A basic solution (pH higher than 7) can be used to capture H2S. Hypochlorite is a
common base. A two-stage scrubber, one to capture NH3 and one to capture H2S, may
be used to scrub both NH3 and H2S from the ventilation air. Scrubber liquid pH does
not affect PM removal.
Liquid-to-Air Ratio
Wet scrubber effectiveness depends on the ratio of scrubber liquid flow rate to
the exhaust air flow rate through the scrubber. Liquid-to-air ratios for prototype scrub-
bers suggest that ratios from 4 x 10-4 to 2 x 10-6 can be used. These ratios mean that
from 2,500 to 500,000 times more air than scrubbing liquid is flowing through the wet
scrubber. Research on liquid-to-gas ratios is ongoing. The particular liquid-to-air ratio
needed depends on how much gas (i.e., NH3, H2S, or other gases) removal is needed
and the operating temperature.
Retention Time
Retention time describes how much time the air is in contact with the scrubbing
liquid. Factors affecting the retention time include liquid velocity, air velocity, flow con-
figuration, and scrubber size. Retention time can range from 0.4 to 8 seconds (s). With
a spray-type wet scrubber using a liquid with 1 percent weight/volume sulfuric acid, 90
percent of the ammonia in an airstream can be removed in 0.4 s. Using plain water, it
takes 8 s to remove 84 percent of the ammonia in an airstream.
Air Velocity
The air velocity through wet scrubbers is recommended to be less than 4.3 m/s
(850 ft/min). Agricultural fan air exhausts can be slowed before entering the scrubber
by increasing the cross-sectional size of the scrubber. Increasing scrubber size usually
increases initial costs.
Pressure drop
Pressure drop describes the flow resistance caused by the scrubber. The exhaust
fans must overcome the pressure drop. When selecting a wet scrubber, the capability
of the ventilation fans to overcome the scrubber pressure drop must be considered.
Most animal facilities use axial fans, which are capable of delivering large amounts of
airflow, but are very sensitive to increases in pressure drop.
Mitigation Strategies: Wet Scrubbers AIR QUALITY EDUCATION IN ANIMAL AGRICULTURE 3
4. Wet Scrubber Types
Wet scrubbers can be used to collect both PM and gas. Scrubbers have been
developed specifically for particulate removal or gas removal (Figure 2). PM collection
is improved by disturbing the airflow to “shake out” particles, i.e., by enhancing impac-
tion with droplets.
Wet scrubbers Gas absorption requires a large surface area, which can be created by droplet
breakup or wet sheet formation. Several scrubber types are used in industry for gas
clean air by absorption. To overcome the high pressure drop of industrial-type scrubbers, low pres-
sure drop scrubbers, such as loosely packed bed and spray scrubbers, are commonly
physically trapping used in AFOs.
particulate matter Loosely packed bed scrubbers use a packing material, such as ceramic saddles or
rings, to maximize the wetted surface area for PM and gas collection. They operate
on wet surfaces and well in cross-flow, concurrent-flow, and counter-current-flow arrangements.
absorbing gases Loosely packed, randomly positioned packing materials in packed bed scrubbers
can have a small pressure drop. Packed bed scrubbers are prone to plugging if the PM
into the liquid. concentration is too high. Concurrent-flow operation can reduce the potential for early
plugging.
Fiber bed scrubbers are a subset of packed bed scrubbers. They use fibers, such as
fiberglass or steel fibers, for the wetted packing media. Fiber beds best operate using
a cross-flow arrangement, which prevents pore plugging. Fiber bed scrubbers are
also useful in bio-scrubber applications because they allow microbial growth on fibers,
which can improve VOC breakdown.
Spray scrubbers use nozzles to spray very fine droplets into a chamber where the
liquid and air come into contact. Finer droplets increase the contact area between the
air and liquid, but they can be more difficult to remove from the air stream before the
air leaves the scrubber. Spray scrubbers are effective in all three flow configurations,
cross, concurrent, and counter-current. Spray scrubbers have the lowest airflow pres-
sure drop among scrubbers. Spray scrubbers operating in concurrent-flow and cross-
flow operations are least prone to plugging.
Wet Scrubber Costs
Wet-scrubber system costs include initial capital and installation, energy, liquid and
chemical, maintenance, and scrubber effluent storage and disposal costs. Table 1 gives
typical capital and operating and maintenance (O&M) costs for different wet scrubbers
Air out Air out
Mist Mist
eliminator eliminator Liquid Fiber
in bed
Liquid
Liquid in in
Air Air
with out
Random in
spray
nozzles packing
Liquid
Air Air out
in in
Liquid Liquid
out out
A B C
Figure 2. Schematic diagrams of spray scrubber (A) packed bed, (B) and
fiber-bed, (C) scrubbers.
4 AIR QUALITY EDUCATION IN ANIMAL AGRICULTURE Mitigation Strategies: Wet Scrubbers
5. Table 1. Common industrial wet scrubber capture efficiencies and costs (Sources: USEPA, 2008, Schnelle and Brown, 2002 ).
Capture Efficiency (%) Costs (based on 2002 $ value)
Material Volatile
Scrubber type Inorganic Capital cost O&M cost Total cost
removed PM organic
gases ($/ft3) ($/ft3) ($/ton)
compounds
Spray PM / Gas 70 – 90 50 – 95 95 – 99 $2 – $6 $1.5 – $30 $45 ––$860
$45 $860
Packed bed Gas 70 – 99 95 – 99 $11 – $55 $15 – $49 $100 – $500
$100 – $500
Fiber bed PM / Gas 70 – 90 70 – 99 $1 – $3 $1.6 – $ 36 $36 – – $344
$36 $344
Impingement PM / Gas 50 – 99 90 – 99 $4 – $11 $3.1 – $44 $94 – $1,300
Mechanical PM 80 – 99 $2.6 – $ 17 $3 – $79 $60 – $1,400
Venturi PM 70 – 99 $2.5 – $21 $4.4 – $120 $70 – $2,400
O&M = operation and maintenance
in industrial applications. Capital costs range from $1 to $55 per standard cubic foot per
minute (scfm) of air treated, based on 2002 dollar value. Spray scrubbers and fiber-bed
scrubbers were least expensive; mechanically aided and venturi scrubbers were most
expensive at that time.
O&M costs include energy costs for pumping the liquid and blowing the air
through a wet scrubber and any chemicals used. Capital costs include initial equip-
ment, installation, and construction costs.
Pilot-scale scrubber studies have reported capital and operating costs. Marsh et
al. (2003) spent $1,632 per exhaust fan on capital costs and $75 per year for operating
costs for scrubbers on a swine nursery. The total cost was $0.13 per pig space. The
low scrubber costs were due to the low PM, NH3, and H2S concentrations of the ex-
haust air, which required a smaller scrubber and less scrubbing liquid. Melse and Ogink
(2005) used scrubbers with higher pollutant loads and average removal efficiencies
greater than 90 percent. They reported an investment cost of $42 per pig or $1.30 per
broiler. The operating cost was $14.82 per pig and $0.27 per broiler. Chemical costs
were 14 percent and 37 percent of operating costs. The operating costs included fan
Four main
power, pump power, and scrubbing liquid consumption. Fan power depended on the
pressure drop through the scrubber. Pump power depended on the liquid flow rate.
characteristics
affect scrubber
Wet Scrubber Limitations effectiveness: flow
While wet scrubbers can effectively remove some gases and PM, their use is lim- configuration,
ited in animal facilities because of their high pressure drop and relatively high initial and
operating costs. Scrubbers also require a system to handle the scrubber liquid effluent. scrubbing liquid
Development of low cost and high efficiency wet scrubbers that do not significantly
affect axial fan operation needs further study. Some of the challenges are: composition,
Clogging. Wet scrubbers can become clogged with accumulated PM if the air liquid-to-air ratio,
being treated has high PM concentrations (especially fibrous particles or feathers). Par-
ticulate matter can accumulate in the packing material and restrict or block the airflow. and retention time.
The risk of wet scrubber clogging can be reduced by increasing the liquid flow or using
either a cross- or concurrent-flow configuration.
Water Use. Wet scrubbers need to have sufficient and economical water supplies.
Wet scrubbers can consume substantial quantities of water. The wastewater handling
is an important consideration. Even if chemicals are not used, the gases dissolved in
the water make the scrubber liquid effluent unsuitable for discharge to public waters
(i.e., streams, lakes, or wetlands). Scrubber effluent can be applied to cropland or
added to a manure storage unit or treatment system in compliance with local, state,
and federal regulations. Recycling scrubber effluent reduces wastewater generation.
Mitigation Strategies: Wet Scrubbers AIR QUALITY EDUCATION IN ANIMAL AGRICULTURE 5
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6 AIR QUALITY EDUCATION IN ANIMAL AGRICULTURE Mitigation Strategies: Wet Scrubbers