A12 Use of biological air scrubbers in pig housing

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A12 Use of biological air scrubbers in pig housing

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Sector

Livestock farming

Net Effect

2

NH3

1

N2O

4

NO2

4

Nr to water

3

N2

4

Reliability

Promising

Tech. rqmts.

High

Overview

The application of biological air scrubbers or biotrickling filters (Figure 1), represents a promising method for enhancing nitrogen management in pig housing. These systems have demonstrated successful implementation across various countries, effectively mitigating not only ammonia emissions but also addressing concerns related to fine dust and odour (Ndegwa et al., 2008; Bittman et al., 2014; Sutton et al., 2022). Biotrickling filters reduce ammonia emissions by facilitating microbial conversion of ammonia to less volatile forms, contributing to improved air quality within pig facilities.  

Advanced multi-stage scrubbers have emerged to tackle elevated dust loads, addressing a common challenge in poultry environments. However, the utilisation of bio-filters may introduce a trade-off between ammonia reduction and potential increases in other nitrogen losses, such as nitrous oxide, nitrogen oxide, and di-nitrogen (Bittman et al., 2014; Sutton et al., 2022). The potential recovery (and recycling) of the collected reactive nitrogen from biological air scrubbers could offset this rise, as it may reduce the necessity for additional fresh nitrogen fixation for the manufacture of chemical fertilisers.  

Careful consideration of the specific operational parameters and conditions is imperative to achieve a balanced approach, maximising the benefits of reduced ammonia emissions while minimising the potential for elevated nitrogen losses in alternative forms. As such, the implementation of biological air scrubbers holds significant potential in the context of improving nitrogen management within pig housing, warranting comprehensive evaluation and adaptation to specific operational contexts to ensure sustainable and effective results.  

This measure is regarded as promising in terms of nitrogen emissions reduction, but carries high technological requirements. 

Biological air scrubber to capture ammonia emissions from livestock housing. Picture source: https://www.bigdutchman.com/en/pig-production/news/detail/air-cleaning-tried-tested-air-scrubber-dlg-certification/

Figure 1. Biological air scrubber to capture ammonia emissions from livestock housing. Picture source: https://www.bigdutchman.com/en/pig-production/news/detail/air-cleaning-tried-tested-air-scrubber-dlg-certification/

Measure Efficiency

Biological air scrubbers have been found to reduce ammonia emissions by 70%, whilst also removing fine dust and odour (Ogink and Bosma, 2007). To deal with the high dust loads, multistage air-scrubbers with pre-filtering of coarse particles have been developed (Melse and Ogink, 2005; Ogink and Bosma, 2007). In a study on pig and poultry houses in the Netherlands, Melse and Ogink, (2005) found the ammonia elimination achieved by Biological air scrubbers displayed ammonia removal ranging from -8% to +100%, averaging at 70%. Conversely, acid scrubbers ranged from 40% to 100%, with a mean of 96%. Notably, odour removal through acid scrubbers ranged between 3% and 51%, with an average of 27%, whereas biological air scrubbers exhibited odour removal ranging from -29% to +87%, averaging at 51%.  

In a review of ammonia emission mitigation techniques for concentrated animal feeding operations, Ndegwa et al., (2008) provide the following summaries of studies on air filtration to remove ammonia emissions. Sun et al., (2000) assessed a 200 mm deep biofilter composed of a blend of compost and wood chips to ascertain its efficiency in ammonia removal from pig housing ventilation air. At a biofilter moisture content of 50% and a retention time of 20 seconds, this system demonstrated an average ammonia removal rate of 83% from the carrier air. Tanaka et al., (2003) documented a notable ammonia reduction of 94% within the initial 72 hours of treatment using a biofilter comprising finished compost (comprising cattle manure and sawdust) for composting air. Hong and Park, (2005) achieved a 100% ammonia removal efficiency using a biofilter composed of a 500 mm deep mixture of 50:50 manure compost and coconut peel, treating air emanating from a composting pile involving dairy manure and crop residues.  

In pilot-scale investigations, Sheridan et al., (2002) evaluated a wood chip biofilter with a depth of 500 mm for diminishing ammonia in exhaust air from a pig finishing building. Depending on the volumetric loading rate, this biofilter, utilising 20 mm screen size wood chips, effectively eliminated between 54% and 93% of ammonia. To uphold biofilter efficiency, a filter bed moisture level of 63% or higher was recommended. A biofilter employing a mix of pine and perlite achieved a substantial ammonia removal rate of 96% from ventilation air originating from a pig rearing facility in a pilot-scale setup (Chang et al., 2004). In the context of a contemporary 2400-sow farrow-to-wean unit, Kastner et al., (2004) demonstrated that a biofilter constructed with pre-screened yard waste compost achieved ammonia reduction rates ranging from 25% to 95%, contingent upon the residence time and inlet ammonia concentration. Lastly, Martinec et al., (2001) conducted an evaluation encompassing diverse biofilter materials (biochips, coconut peels, bark-wood, pellets and bark, and compost) for ammonia reduction in pig operations, resulting in ammonia reduction percentages ranging from 9% to 26%. 

How to implement

Installing biological air scrubbers in pig housing involves a systematic approach to ensure effective ammonia and odour reduction while considering the specific needs of the facility. 

  • Assessment and Planning: Conduct a thorough assessment of the pig housing facility, including its size, layout, ventilation system, and existing ammonia levels. Determine the optimal location for installing the biological air scrubber, considering airflow patterns and accessibility. 
  • System Design: Work with agricultural engineers and experts to design a biological air scrubber system tailored to the specific facility and needs. The system typically consists of a biofilter or biotrickling filter. A biofilter contains a medium (such as wood chips) that supports the growth of ammonia-consuming microorganisms. A biotrickling filter combines a medium with a water spray to enhance microbial activity. 
  • Microbial Inoculation: Source or culture beneficial microorganisms that are effective at breaking down ammonia. Common examples include Nitrosomonas and Nitrobacter bacteria. Inoculate the biofilter or biotrickling filter with these microorganisms to establish a healthy microbial population. 
  • Installation: Install the biological air scrubber in the designated location within the pig housing facility. Connect the scrubber to the existing ventilation system to ensure that air passes through the filter. 
  • Operation and Maintenance: Regularly monitor ammonia levels using appropriate sensors and testing methods. Maintain optimal conditions for microbial growth, including temperature, humidity, and nutrient levels. Provide a consistent airflow through the scrubber to ensure efficient ammonia removal. Regularly inspect and clean the system components to prevent clogs and maintain microbial activity. Replace the filter medium periodically to prevent buildup of ammonia and microbial byproducts. 
  • Record Keeping: Keep detailed records of ammonia levels, system maintenance, and any adjustments made to the scrubber. Regularly review these records to identify trends and make necessary improvements to the system. 
  • Training and Education: Train farm workers on the proper operation and maintenance of the biological air scrubber system. Educate workers about the importance of ammonia reduction for animal health and environmental sustainability. 
  • Continuous Improvement: Regularly evaluate the system's performance and its impact on ammonia reduction. Consider incorporating technological advancements or process improvements to enhance the system's efficiency. 

Remember that successful implementation of a biological air scrubber system requires collaboration between agricultural experts, engineers, and microbiologists. It's also important to adapt the system to the specific conditions of the pig housing facility to achieve the best results. 

Benefits

Implementing biological air scrubbers in pig housing offers a range of benefits, including: 

It is important to note that the effectiveness of biological air scrubbers can vary based on factors such as system design, maintenance, and the specific conditions of the pig housing facility. To maximise the benefits, proper design, installation, and ongoing management are crucial. Consulting with agricultural engineers, air quality experts, and relevant authorities can help ensure the success of the implementation. 

Costs

Captial Costs

Installing biological air scrubbers in pig housing entails various potential capital costs, including: 

  • The capital costs can vary based on factors such as the size of the poultry housing facility, chosen biofilter technology, local labour and material costs, and specific facility requirements. Conducting a comprehensive cost-benefit analysis is crucial before implementing biological air scrubbers to ensure a clear understanding of potential expenditures and the long-term returns on investment. 

    Operational Costs

    The operational costs associated with installing biological air scrubbers in pig housing encompass various ongoing expenses, including: 

  • It's important to consider that operational costs can vary depending on factors such as the scale of the pig housing facility, biofilter technology, local utility rates, and specific operational practices. Conducting a thorough cost analysis, accounting for both capital and operational expenses, is essential to determine the overall financial implications of implementing biological air scrubbers and to assess their long-term viability and benefits. 

    Risks

    Implementing biological air scrubbers in poultry housing comes with several potential risks and challenges: 

    It is important to carefully evaluate these risks and challenges against the potential benefits when considering the installation of biological air scrubbers in pig housing. Consulting with experts in agricultural engineering, air quality management, and microbiology can help mitigate these risks and ensure a successful implementation. 

    References

    A. Tanaka, K. Yakushido, and and C. Shimaya. 2003. Adsorption process for odor emission control at a pilot scale dairy manure composting facility. Air Pollution from Agricultural Operations - III. American Society of Agricultural and Biological Engineers, St. Joseph, MI. p. 189–196 

    Bittman, S., M. Dedina, C.M. Howard, O. Oenema, and M.A. Sutton, editors. 2014. Options for Ammonia Mitigation: Guidance from the UNECE Task Force on Reactive Nitrogen. Centre for Ecology and Hydrology, Edinburgh, UK. 

    Chang, D.I., S.J. Lee, and W.Y. Choi. 2004. A Pilot-scale Biofilter System to Reduce Odor from Swine Operation. 2004, Ottawa, Canada August 1 - 4, 2004. American Society of Agricultural and Biological Engineers, St. Joseph, MI 

    Hong, J., and K.J. Park. 2005. Compost biofiltration of ammonia gas from bin composting. Bioresour. Technol. 96(6): 741–745. doi: 10.1016/j.biortech.2004.10.008. 

    Kastner, J.R., K.C. Das, and B. Crompton. 2004. Kinetics of ammonia removal in a pilot-scale biofilter. Trans. ASAE 47(5): 1867–1878. doi: 10.13031/2013.17588. 

    Martinec, M., E. Hartung, T. Jungbluth, F. Schneider, and P.H. Wieser. 2001. Reduction of gas, odor and dust emissions from swine operations with biofilters. 2001 Sacramento, CA July 29-August 1,2001. American Society of Agricultural and Biological Engineers, St. Joseph, MI 

    Melse, R.W., and N.W.M. Ogink. 2005. Air Scrubbing Techniques for Ammonia and odor reduction at livestock operations: Review of on-farm research in the Netherlands. Trans. ASAE 48(6): 2303–2313. doi: 10.13031/2013.20094. 

    Ndegwa, P.M., A.N. Hristov, J. Arogo, and R.E. Sheffield. 2008. A review of ammonia emission mitigation techniques for concentrated animal feeding operations. Biosyst. Eng. 100(4): 453–469. doi: 10.1016/j.biosystemseng.2008.05.010. 

    Ogink, N.W.M., and B.J.J. Bosma. 2007. Multi-phase airscrubbers for the combined abatement of ammonia, odor and particulate matter emissions. Proc. Int. Symp. Air Qual. Waste Manag. Agric. 

    Sheridan, B., T. Curran, V. Dodd, and J. Colligan. 2002. Biofiltration of odour and ammonia from a pig unit - A pilot-scale study. Biosyst. Eng. 82(4): 441–453. doi: 10.1006/bioe.2002.0083. 

    Sutton, M., C. Howard, K. Mason, W. Brownlie, and Cm. Cordovil, editors. 2022. Nitrogen Opportunities for Agriculture, Food & Environment. UNECE Guidance Document on Integrated Sustainable Nitrogen Management. UK Centre for Ecology & Hydrology, Edinburgh, UK. 

    Y. Sun, C. J. Clanton, K. A. Janni, and G. L. Malzer. 2000. Sulfur and nitrogen balances in biofilters for odorous gas emission control. Trans. ASAE 43(6): 1861–1875. doi: 10.13031/2013.3091. 

    Authors

    • Will Brownlie

      UK Centre for Ecology and Hydrology, Scotland