Abstract:
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Airborne emissions from livestock production are nowadays one of the major concerns of this activity. For this reason, the reduction of these emissions is a requirement in many countries. The development of abatement ...[+]
Airborne emissions from livestock production are nowadays one of the major concerns of this activity. For this reason, the reduction of these emissions is a requirement in many countries. The development of abatement techniques for the reduction of emissions needs for accurate knowledge about their magnitude. Emission measurement techniques arise then as a key issue. The development of measurement techniques considering not only the accuracy of the results but also the optimization of resources is needed. In this sense, in this thesis a tool and three options for the rationalization on the use of resources when measuring airborne emissions are investigated. The tool is the uncertainty analysis and the three options are: downscaling measurements, indirect measurement of airflow rates and reduction of sampling rates. In this thesis, theoretical and practical studies were conducted to determine the suitability of these techniques to obtain reliable data from more rational measurements on airborne emissions. Firstly, an uncertainty model was developed in order to assess the trustworthiness of the results when determining N2 and N2O emissions from a biological scrubber using a combined N-balance in air and water. This model was later partially validated throughout an experimental work in a chemical scrubber. The uncertainty model and the experimental work agreed in the key results of both studies, finding that N-balances were not successful for the proposed aims. Secondly, a flux chamber for the measurement of gas emissions from rabbits was designed and built. A measuring protocol for gas emissions from both animals and their manure was also developed. This chamber was later used to determine the CO2 emission rate from fattening rabbits during the whole fattening cycle. Using this CO2 emission rate from fattening rabbits, the carbon dioxide balance was tested as an option to determine the ventilation rate from fattening rabbit houses. The results of these balances were
compared with direct measurements of ventilation rates finding no statistical differences.
Finally, the effect of reducing sampling when measuring ammonia emissions from
livestock facilities was evaluated. Emissions calculated using semi-continuous
measurements of NH3 concentrations and airflow rates were compared with emissions
calculated on 24-hour average values for these parameters. The error committed with
these low time-resolution measurements resulted to be low in comparison with other
error sources committed when measuring emissions from livestock facilities. The main
conclusion of this work is that there are available techniques that allow optimizing the use
of resources of measurement processes, by keeping the accuracy of the results.
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