Particulate matter emission from livestock houses: measurement methods, emission levels and abatement systems

Animal houses are extremely dusty environments. Airborne particulate matter (PM) poses a health threat not only to the farmer and the animals, but, as a result of emissions from ventilation systems, also to residents living in livestock farming areas. In relation to this problem, the objectives of this thesis were threefold. The first objective was to increase our understanding and knowledge of concentrations and emission rates of PM in commonly applied animal housing systems. This objective is worked out in chapter 2 which presents a national emission survey into the concentrations and emissions of PM, which covered 13 common housing systems for poultry, pigs, and dairy in the Netherlands and included 202 24-h measurements at 36 farms. The emission figures from this work are currently used in the Netherlands in environmental permit granting procedures (to model the local dispersion of PM10 in the vicinity of livestock farms), to estimate national emissions, to compute large-scale pollutant concentration maps, and to annually evaluate the state of affairs of the National Air Quality Cooperation Programme (NSL). The second objective was to develop, test, and validate technologies to mitigate PM concentrations and emissions in poultry farms and ultimately contribute to cleaner outdoor air. This objective is worked out in chapters 3 through 7. Chapters 3 and 4 describe two experiments, one in broilers, one in layers, that investigated the effects of spraying rapeseed oil droplets onto the litter of poultry houses which prevents particles from the litter from becoming airborne. On the basis of chapters 3 and 4, chapter 5 describes a field evaluation of four systems that mitigate PM emissions by reducing indoor concentrations: a fixed oil spraying system, an autonomously driving oil spraying vehicle, a negative air ionization system, and a positive air ionization system. Chapter 6 describes a field evaluation of two ‘end of pipe’ systems to remove PM from the exhaust air of poultry farms, namely: a dry filter wall and an electrostatic precipitator. Chapter 7 describes an emission survey carried out at a total of 16 commercial poultry farms with an ‘end of pipe’ manure drying tunnel. This chapter aimed to elucidate the PM abatement potential and possible additional emissions of ammonia and odor of these tunnels. Furthermore, this chapter aimed to elucidate the perspective of two strategies to reduce any additional emissions from the manure drying tunnels. The results from chapters 5 through 7, carried out at commercial farms, have been used to adopt accurate PM removal figures in Dutch regulations on PM emissions from livestock houses. Finally, the third objective was to determine the applicability (in terms of acceptable accuracy and comparability) of alternative PM10 measurement methods – i.e., alternative to the ‘cyclone sampler’ developed prior to this thesis and used in chapters 2 through 7. Such alternative samplers could then be applied in future for determination of PM10 emission rates of animal houses. This objective has been worked out in chapter 8 as an equivalence study between the European reference sampler for PM10 (described in EN 12341) and five different candidate measurement methods (the cyclone sampler, a beta-ray attenuation sampler, a microbalance device, and two light-scattering devices) in four different environments (a fattening pig house, a laying hen house, a broiler house, and an office room). Results show that all samplers showed a systematic deviation from ‘true’ values, that between-device variation was relatively high, and that samplers started to dysfunction after about 432 to 500 h of operation. Therefore, appropriate measures (such as duplicate sampling, correction factors, and more frequent servicing) must be taken. The results can be used to harmonize PM10 measurement methods across institutes and to further increase the availability of samplers for the measurement of PM10 in animal production