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

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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
Page 1: An ASABE Conference PresentationPap
Page 5 and 6: The composition of the exhaust air

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

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