DEVELOPMENT OF A CHEMOMETRIC METHOD TO MEASURE ODOUR FROM LIVESTOCK PRODUCTION

Transcription

1 DEVELOPMENT OF A CHEMOMETRIC METHOD TO MEASURE ODOUR FROM LIVESTOCK PRODUCTION DEPT. OF ENGINEERING AIR QUALITY ENGINEERING RESEARCH GROUP ANDERS FEILBERG MICHAEL JØRGEN HANSEN DEZHAO LIU METTE MARIE LØKKE præsen TATION

2 some facts Full-range university with 4 broad faculties 40,500 students 3,000 PhD students & Post Docs 11,000 employees 11,330 publications in

3 AU Foulum AARHUS Experimental ANDERS animal PETER S. ADAMSEN facilities & herds Feed mills & experimental abattoir 450 hectares of farmland Test facilities for machinery Greenhouses, semi-field and lysimeter facilities Biomass pretreatment and fractioning Livestock emission lab Air physic labs 3

4 AU Foulum biogas and biorefinery plant AARHUS Facilities Farm scale biogas plant Liquid and solid feeding Pretreatment systems (extruder etc.) Separation (decanting centrifuge) Straw incineration line Pilot plant (2 30-m 3 & 2 10-m 3 ) Research hall for lab scale research Biogas upgrading (methanisation of CO 2 ) Planned: biorefining of green biomass (decentralised fractionation, protein extraction, dewatering, drying etc. 4

5 Why chemical analyses of odour? Better quality is possible: Quality assurance handling: Accuracy Reproducibility Calibration Cost e.g. fewer number of samples to show significant difference Results are independent of laboratories Process optimisation Compound specific effect of specific technology Registration of small differences Several configurations can easily be tested 5

6 Odour concentration (OU E/m 3 ) AARHUS 3000 DMRI EUROFINS LUFA Identical samples from a pig house collected in bags and analysed by odour laboratories at the time huge variation Data from Anders L. Riis, VSP, Meddelelse nr

7 Can chemical analyses represent odour? Odour concentration or strength by olfactometry: Degree of dilution before an odour sample just can be perceived. What about intensity or hedonic tone Odour from livestock production and olfactometry: Big differences between laboratories for absolute values, but also for relative differences Losses of compound in the sampling materials Loss or delay of compounds in the olfactometer itself The noses are not exposed to a representative sample 7

8 Pump MS GC Adsorption tubes and TD-CG/MS ATD-tube TD 8

9 Conclusion on TD GC/MS work TD-GC/MS is able to sample, identify and quantify almost all odorants investigated in this study Field blinds are important and data should always be corrected for field blind values Small thiols like methanethiol are not collected on the sorbents. The method is very useful for optimization of odor reduction technologies. Hydrogen sulfide and other reducing sulfur compounds (except dimethyl sulfide) have to be quantified by alternative methods, e.g. gold film detectors (e.g. Jerome 631-X) or on-line mass spectrometer (e.g. MIMS) 9

10 Bovema Air cleaner 400 Concentration (µg/m³) Before After step 1 After 50 0 Data from Danish Meat Association 10

11 Concentration, ppb AARHUS Bad recovery in bags with odour samples methyl phenol Tedlar moist Tedlar dry Nalophan moist Nalophan dry Time, hours 11

12 Concentration, ppb AARHUS Contribution from sulfur compound is enforced H 2 S Tedlar without conditioning Tedlar with conditioning Nalophan without conditioning Nalophan with conditioning Time, hours 12

13 On-line PTR-MS Proton-transfer-reaction MS Direct MS detection by chemical ionisation H 3 O + H 3 O + + R(VOC) RH + + H 2 O Response time < 1 s per compound Very low detection limits ( ~5 ppt) Relative high selectivity (some fractionations) No sampling preparation and no loss of compounds in the sampling line 13

14 How to convert chemical analyses to odour? Odour Activity Values (OAV) = concentration / odour threshold value Dependent of good odour threshold values Tool to prioritise odorants and selection of technology The compounds with the highest OAV contribute / control odour concentration? Chemometric: multivariate statistic applied on chemical analyses Statistical model to predict odour concentration Estimate contribution from individual compounds 14

15 Outlet concentration (ppb) / OAV AARHUS Identification of key odorant based on odour activity values Mean concentration Odor Activity Value H2S MT Trimethylamine Acetic acid DMS Propanoic acid 2,3-Butanedione Butanoic acid C5 acids 4-Methylphenol 3-Methylindole 15

16 Measured odor concentration, LOG(OU E/m 3 ) AARHUS Statistical odour model based on PTR-MS Predicted odour concentration, LOG(OU E /m 3 ) Best correlation for field samples so far! 16

17 Outlet concentration (ppb) / OAV Most important odorant according to model 300 Hydrogen sulfide Methanethiol 4-methylphenol (p-cresol) Trimethylamine Synchronised measurements of odour by olfactometry and odorant by PTR-MS High variation in the analysed samples Best correlation on field samples so far H2S MT Trimethylamine Acetic acid DMS Propanoic acid 2,3-Butanedione Butanoic acid Mean concentration Odor Activity Value C5 acids 4-Methylphenol 3-Methylindole

18 CASE I. Application of slurry 18

19 Methods to pre-concentrate odour: Static box The odorants were preconcentrated in boxes placed over the areas with applied slurry The pre-concentration is necessary due to low detection limit of olfactometry The odour samples were collected after 7-9 min preconcentration in the boxes: According to the VERA protocol, however the odour sample is taken after 7 min instead of 20 min 19

20 Conc (ppb) H2S conc (ppm) AARHUS Spreading of manure on a lawn Time (min) CH3SH HAc DMS P-cresol H2S Feilberg et al

21 Conc. (ppb) AARHUS Spreading of slurry on a lawn II Time (min) H2S MT DMS Feilberg et al

22 Concentration (ppb) AARHUS Control Acidified 1500 Acidified + FeSO Relative time (min) 22

23 Case II: Application of PTR-MS to characterise biological air cleaning Filter matrix: Vertical cellulosic pads with channels First two sections are trickling filters (cross-current) Total retention time in filter: 2-5 s 23

24 Masse H spektrum: S før luftrenser Concentration, nl L Acetic acid CH 3 SH 61 Propanic acid Butanoic acid 75 4-methylphenol 89 Phenol + dimethyl disulphide DMS Indole Skatole Mass-to-charge ratio, m/z

25 Mass 100 spektrum: 35 H efter luftrenser 2 S Concentration, nl L -1 MT Carboxylic acids, aldehydes, ketones, phenols and indoles ~80-99% DMS Hydrogen sulfide (H 2 S): ~75% Methanethiol and dimethylsulfide: ~0-15% Mass-to-charge ratio, m/z 25

26 Concentration, nl L -1 AARHUS Removal of H 2 S in the filter sections :00 12:00 00:00 12:00 00:00 12:00 00:00 12:00 00:00 Before filter 1 After filter 1 After filter 2 After filter 3 26

27 Concentration, ppbv AARHUS Removal of methanethiol (CH 3 SH) /08 20/08 21/08 22/08 23/08 24/08 25/08 26/08 27/08 28/08 29/08 30/08 31/08 01/09 02/09 03/09 Before filter 1 After filter 1 After filter 2 After filter 3 27

28 Summary Olfactometry is insufficient to measure odour emission from livestock production facilities and land application of manure Chemical analyses is better to characterise and optimise emission abatement technology PTR-MS is a very suitable method to measure odorants, but need information from other sources (GC/MS etc.) to assign all the ions It is possible to develop a chemometric model based on synchronised chemical analyses and odour measurements Chemical measurements of odorants (and other VOC) give good and reproducible data, which are important for development and implementation of new technology 28

29 Thank you for your attention 29