Paper No: 200000 - International Conference of Agricultural ...

An ASABE Conference PresentationPaper Number: ILES 12-0833Possible Means of Reduction of Airborne Pollutants Inand From Poultry HousesStefan LinkeTorsten Hinz, Dr.-Ing.Karl-Heinz Krause, Dr.-Ing.Jochen Hahne, Dr. rer. nat.Tatjana Winter, Dipl.-Ing.Johann Heinrich von Thünen-Institut (vTI), Bundesallee 50, 38116 Braunschweig, Germany,stefan.linke@vti.bund.deWritten for presentation at theNinth International Livestock Environment SymposiumSponsored by ASABEValencia Conference CentreValencia, SpainJuly 8-12, 2012Abstract. Measurements were carried out to both quantify the source strength of airborne pollutantsin poultry houses as well as to give the potential of the reduction procedures. For this purposedifferent means are available. They range from preventing the emissions already inside the stable bysmart ventilation systems over conditioning of the air in the barn, for example by fogging up, to endof the pipe techniques like scrubbers and dust separators. Numerical simulations can design smartventilation systems. A multistage facility showed potential in particle reduction as well as in nitrogenreduction.Keywords. airborne pollutants, emission reduction, poultry

IntroductionAnimal production becomes more and more a kind of industrial production. Technical aidssimplify the keeping and raise the profit of the livestock owner. This benefit is not restricted toone kind of animal; a prime example is, however, the laying hen husbandry. Ventilation, feeding,drinking, egg collection and the feces removal by manure belts are highly automated. Onlyinspection round trips are necessary.All this technological progress can not prevent the emission of various kinds of airbornepollutants and odor as well from animal production. With respect to farmers′ and animals′ healthand welfare, the environment and climate change, PM, ammonia and carbon dioxide are mostimportant. While ammonia is produced mainly by cattle, the largest source of PM (dust) ispoultry keeping. According to the EMEP Guidebook (2009) the PM10 emission factor for layersin cages is with 0.017 kg AAP -1 a -1 about 20 times higher than for e.g. cattle with a factor of0.36 kg AAP -1 a -1 if both are based on a 500 kg livestock unit.All gaseous and particulate contaminants which are produced in poultry houses may have aneed for pollutants′ concentration reduction. For this purpose different means are available.They range from preventing the emissions already inside the stable by smart ventilationsystems over conditioning of the air in the barn, for example by fogging up, to end of the pipetechniques like scrubbers and dust separators. All solutions must be adapted to the specialrequirements of the application, which must be known.Poultry houses are planned on the drawing board and nobody knows how the emissionbehavior of the keeping will be. One step further is the use of numerical simulation. The powerof modern computers allows to consider in detail the geometry of a whole stable. Then it ispossible to calculate the flow patterns and the resulting concentration fields inside the barn.Improvements of the ventilation system can be done right before the real stable is built. All thateven goes so far that simulations are used to assess the emission levels of poultry keeping forthe checking of their approvability.Material and MethodsMeasurementsMeasurements were carried out from Winter et al. (2012) in order to quantify the source strengthof airborne pollutants as well as to give the potential of the reduction procedures. Onemeasurement campaign was carried out to acquire concentration levels inside andcorresponding emission flows from layer keepings. A number of 60 keepings were compared.German small group housing systems (n = 28) and aviaries (n = 32) were investigated. Theother poultry measuring run was conducted at a chicken house (cocks and hens) in the timeperiod from June to December 2009.The concentrations of ammonia and PM were measured simultaneously with the air flow rate. Atthe same time additional measurements were done after exhaust air treatments to findseparation efficiencies. Online measuring devices ran up to 48 hours to catch the differences ofday and night time in regard to animal activity. Opto acoustic devices, FTIR andchemiluminescence detectors were used for gaseous pollutants. Light scattering instrumentswere applied to measure particle matter size selectively. Ventilation rates were logged directlyby climate computers or were measured with a fan wheel anemometer or an ultrasonic flowmeter.2

Computational fluid dynamicsIn the following an example will be described of how a prognostic flow model can calculate theaviary stable air input and output flows as well as the emission factors. Flow patterns andammonia distributions of different ventilation setups which are shown in figure 1 are calculatedand visualized with a commercial simulation program. The hull is always the same stable room(length 43.2, width 11.2 and height 3.55 m) but at variable boundary conditions. The variationsare case 1a: air inlet and air outlet at the gables, case 2a: corresponding to 1a) with additionalsuction of fresh air through the inlet openings in the sidewalls (point sources), case 3a: suctionaway of stable air through line sinks in the ridge and suction of fresh air through line sources inthe sidewalls and case 4a: suction away of stable air through point sinks through the ridge andsuction in of fresh air through point sources in the ceiling. The constellations 3b and 4b refer tothose in the cases 3a and 4a, but with the installation of aviary frames.Figure 1. Schemes of different ventilation systems and stable constructions.The calculations were done on a four processor PC. The geometry is meshed with a number of1.4 million cells.Technical meansRoumeliotis and Van Heyst (2008) have collated a list of various best management practices(BMP) at different types of poultry operations which show their reduction potential for ammoniaand particulate matter. Another system is a fogging system which is installed for coolingpurpose primarily. The aim of a still running investigation is the assessment of its capability forabatement of airborne pollutants in poultry productions.Moreover, as end of the pipe technology, a multistage facility is used for the poultry exhaust airtreatment, cf. figure 2. In a first operation step, an endless filter pad secures a dry dustseparation. Above an adjustable pressure drop the filter pad regeneration starts automaticallywith an external vacuum cleaner which collects the dust in a bag. For the ammonia reductiontwo subsequent washing walls with a thickness of 150 mm each are in operation as a finaltreatment step. The filling bodies are irrigated with a pH controlled washing solution. Thewashing liquid discharge is controlled by electric conductivity.3

Figure 2. Configuration of the test facility for the cleaning of poultry exhaust air (1: raw gas;2: filter fleece; 3: scrubber wall 1; 4: scrubber wall 2; 5: clean gas; 6: fleece exhaustion; 7: watertank 1; 8: water tank 2; 9: dust removal; 10: elutriation water tank 1; 11: elutriation water tank 2;12: fresh water supply; 13: sulfuric acid supply).ResultsMeasurementsIn the layer keepings ammonia concentrations could be determined between 1 ppm and 30 ppminside the stables. Dust fraction PM4 is found from < 0.1 mg/m³ during the night up to 8 mg/m³at day time mainly affected by the activity of the birds. Specific events raised the production ofairborne pollutants. Manure removal in keepings with manure belts lowered the ammoniaconcentration inside the stable significantly. An example is given in figure 3 for a German smallgroup housing system.Figure 3. Daily course of ammonia concentration in a German small group housing system.4

The composition of the exhaust air from a chicken house showed considerable fluctuations.High ammonia concentrations up to 30 ppm in maximum were observed in March and fromOctober to December. In the period between July and September the average daily values werenearly constant below 5 ppm. As detected in a layer keeping the ammonia emissions showed anoticeable correlation with the weekly dung removal intervals. After dung removal the NH 3emission was very low but increased significantly till the next dung removal. The relativehumidity and temperature varied from 33.5 to 78.2 % and from 18.4 °C to 33.7 °C, respectively.While methane and total organic carbon concentrations below 3 ppm in average, the carbondioxide concentrations were 1,055 ppm in mean and 3,227 ppm in maximum, which is slightlyover the German limit for animals of 3,000 ppm. The hydrogen sulfide concentration was 1.0ppm in average.Computational fluid dynamicsThe calculation results of cases 3b and 4b (cf. figure 1) are visualized in figure 4. Themovement of massless particles (purple) and the concentration distribution at 0.5 m height isshown. The air movement in the centre of the stable is diminished by installation of the aviaries.The internal stable emissions rise in case 4b due to the increase in turbulence.Figure 4. Flow patterns and ammonia distributions of ventilation setups 3b and 4b.In dependency on the arrangements (1a to 4a without aviary frames and 3b to 4b with aviaryframes) the emission factors shown in figure 5 are in the upper part with regard to the animalnumber (red) resp. with regard to the emission area (green). In the lower part the meanconcentration 0.2 m above the internal emission areas of the stable is shown. The stables withlowest emissions are those ones with line sources and sinks.The numerical simulation showed the emission reduction potential with simultaneousconsideration of stable air quality by using smart ventilation systems.Technical meansMeasurements after exhaust air treatment showed a mean particle separation efficiency of atleast 57 % for the 2.0 – 2.5 µm and 98% for the 6.5 – 7.5 µm particle fraction at filter loadingrates from 1,800 to 3,600 m³/(m² h). The nitrogen balance showed a separation efficiency of72 %.5

Figure 5. Summary of the ventilation variations with regard to emission behavior and air quality.ConclusionSeveral options are available for emission reduction in and from poultry houses. Flow anddistribution patterns of airborne pollutants, for example, can be helpful to design low emissionstables. Avoiding turbulence by using intelligent ventilation systems is a promising way toreduce ammonia emissions. Proper dimensioned and operated exhaust air treatment systemsensure a reduction of at least 70 % for ammonia and 98 % for the particles > 6.5 µm.ReferencesJournal articleRoumeliotis, T. S. and B. J. Van Heyst. Summary of Ammonia and Particulate Matter EmissionFactors for Poultry Operations. 2008 J. Appl. Poult. Res. 17:305–314.Winter, T., Hinz, T., Zierke, C., Lippmann, J., 2011. Hen or manager - who is responsible fordust and ammonia in the stable? Landtechnik 67 (2012), no. 2, pp. 127–132.Online SourceEMEP/EEA Air pollutant emission inventory guidebook – 2009 (2009). Part B, 4B Animalhusbandry and manure managements [online]. Available at:http://www.eea.europa.eu/publications/emep-eea-emission-inventory-guidebook-2009/part-b-sectoral-guidance-chapters/4-agriculture/4-b/4-b-animal-husbandry-andmanure-management.pdf.6