Real-time quantification of emissions of volatile organic compounds from land spreading of pig slurry measured by PTR-MS and wind tunnels

Dezhao Liu; Tavs Nyord; Li Rong; Anders Feilberg

doi:10.1016/j.scitotenv.2018.05.149

Real-time quantification of emissions of volatile organic compounds from land spreading of pig slurry measured by PTR-MS and wind tunnels

Sci Total Environ. 2018 Oct 15:639:1079-1087. doi: 10.1016/j.scitotenv.2018.05.149. Epub 2018 May 26.

Authors

Dezhao Liu¹, Tavs Nyord², Li Rong², Anders Feilberg³

Affiliations

¹ College of Biosystems Engineering and Food Science, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, China; Department of Engineering, Aarhus University, Hangoevej 2, Aarhus N 8200, Denmark. Electronic address: dezhaoliu@zju.edu.cn.
² Department of Engineering, Aarhus University, Hangoevej 2, Aarhus N 8200, Denmark.
³ Department of Engineering, Aarhus University, Hangoevej 2, Aarhus N 8200, Denmark. Electronic address: af@eng.au.dk.

PMID: 29929277
DOI: 10.1016/j.scitotenv.2018.05.149

Abstract

Volatile organic compounds (VOC) and hydrogen sulfide are emitted from land spreading of manure slurry to the atmosphere and contribute to odour nuisance, particle formation and tropospheric ozone formation. Data on emissions is almost non-existing partly due to lack of suitable quantitative methods for measuring emissions in full scale. Here we present a method based on application of wind tunnels for simulation of air exchange combined with the use of online mass spectrometry (PTR-MS). The focus was on odorous VOC but all relevant VOC were included. A method for quantification of VOC emission based on calculated proton-transfer reaction rate constants was validated by comparison to reference concentrations for typical VOC emitted from pig manure slurry. Wall losses of volatile sulfur compounds in the wind tunnels were assessed to be insignificant and recoveries >95% were observed for these compounds. An influence of air exchange rate was clearly observed highlighting the need to identify realistic air exchange rates for future application of the method. Emission data was obtained for spreading of pig manure slurry as an example of an important source of gases. Emissions were monitored for ~37 h following land spreading and time-resolved emission data was presented for the first time. Highest emissions were observed for short-chain volatile carboxylic acids (C₂-C₆) with acetic acid being the most abundant compound. Emission peaks were observed immediately following application and were followed by declining emissions until the second day at which emissions reached a second peak for several compounds. This second emission peak was speculated to be caused by a temperature-induced diurnal effect. Emissions of volatile sulfur compounds occurred on a short time-scale and ceased shortly after application. Odour activity values were dominated by C₄-C₅ carboxylic acids and 4-methylphenol with a less pronounced influence of 4-methylphenol on day 2.

Keywords: Emission quantification; Odorant; PTR-MS; Slurry application; Volatile organic compounds; Wind tunnel.