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Swine waste odors : effects of gas stripping Fattori, Michael 1979

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C • ?• WINE WASTE ODORS: EFFECTS OF GAS STRIPP MICHAEL FATTORI 3,5c. University of Toronto, 1976 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OE MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES DEPARTMENT OF AGRICULTURAL MECHANICS We accept this thesis as conforminc? to the .required standard THE UNIVERSITY OF BRITISH COLUMBIA April, 1979 (c) Hichnel Fattcri, 1979 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of BIO RESOURCE ENGINEERING The University of British Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date AUGUST 25 1979 = 75-511E XX ABSTRACT Liquid anaerobic waste collected from a swine finishing barn was chemically investigated. Various phenols, amines, sulfides and organic acids were identified in the waste and were shown to contribute to its odor. The rapid reduction in odor intensity brought about by short term aeration of the waste was studied with respect to these different compounds. The effectiveness of odor reduction by aeration was found to be contingent on the waste's pH. Reasons for this phenomenon are presented in terms of ionization constants for solutes, previously shown to be present in the waste. 111. TABLE OF CONTENTS CHAPTER ABSTRACT ii ACKNOWLEDGEMENTS TABLE OF CONTENTS iii LIST OF FIGURES v LIST OF TABLES v l 1 1 I INTRODUCTION 1 Objectives 4 II LITERATURE REVIEW 6 III MATERIALS AND METHODS 11 3.1 Collection of waste 11 3.2 Aqueous phase analysis 12 3.2.1 Sample preparation 12 3.2.2 General extraction and concentration 12 3.2.3 pll selective extraction 13 3.2.4 Analytical conditions 14 3.2.5 Analytical procedures 15 3.2.6 Gas chromatograph/rttass spectrometer analysis 16 3.3 Vapor phase analysis 16 3.3.1 General setup for heaclspace analysis 16 3.3.2 Analytical conditions 20 3.3.3 Analytical procedures 21 3.4 Sniff-Port ~ 21 3.5 Aeration of samples 23 3.5.1 Laboratory scale aeration 23 3.5.2 Large sea1e aeration 23 IV THEORY 4.1 Extraction efficiency 25 4.2 Effect of drying agents 2 8 4.3 Concentration effects 29 4.4 pH effect ' 30 iv. TABLE OF CONTENTS (Continued) CHAPTER PAGI V ' RESULTS AMD DISCUSSION 36 5.1 Sample collection and preservation 36 5.2 Identification of compounds in waste • 37 5.2.1 Selection of compounds for i d entification 3 7 5.2.2 Identification based on column .retention time 43 5.2.3 GC/HS analysis 49 5.3 Odor potential of compounds identified in waste 5 7 5.4 Quantitation of compounds 5 8 5.5 Effect of pH on odor of waste 59 VI AERATION OF WASTE 61 6.1 Aerating effect on headspace analysis 61 6.2 Aeration effect on liquid phase analysis 6 6 6.3 General discussion 72 VII CONCLUSIONS 7 8 SUGGESTIONS FOR FURTHER STUDY 79 APPENDIX A Name manufacturer and lot % of chemicals used 80 APPENDIX B Olfactory thresholds of relevant compounds 84 LITERATURE CITED LIST OF FIGURES FIGURE P^Jl 1 Frontal view of gas sampling valve in situ showing, a) 0.25 and b) 1.00 cc sampling loops 18 2 Frontal view of gas sampling container showing sampling configuration, a,b) sampling loops; c) catheter; d) sampling vessel; e) valve lever 19 3 Schematic diagram of operation of gas sampling valve 19 4 Frontal view of sniff-port with insulation removed showing carrier stream exit tube (actual size). a) aluminum block; b) heater; c) carrier gas exit tube; d) flame ionization detector, 22 Chromatogram of ether extract concentrate 2 4 hours after collection of waste Chromatogram of ether concentrate after storage for 6 days at 0°C Chromatogram of ether extract concentrate of waste. Numbered peaks represent com-pounds in the waste sicrnificant in terms of their odor 38 40 3 Chromatogram of ether extract concentrate of waste with odor assessment of each peak 41 9 Chromatogram of ether extract of low pH waste with odor assessment of each peak 42 10 Chromatogram of ether extract of low pH waste on Silar 10c column r 11 Chromatogram of a mixture of ethanoic, propanoic, butanoic, pentanoic, hexanoic and heptanoic acids in ether on Silar 10c column 46 v i . LIST OF FIGURES (Continued) FIGURE PAGE 12 Chromatogram of ether extract at low pH waste on"diethylene glycol succinate (DEGS) column 4 7 13 Chromatogram of ethanoic, propanoic,, butanoic, pent.ano.ic, hexanoic and heptanoic acids in ether on DEGS column 4 8 14 Chromatogram of ether extract at low pH waste with ethanoic, propanoic,, butanoic, pentanoic and hexanoic acids added. Silar 10c column 49 15 Mass spectrum of compound represented by peak 2 in Figure 7. Identified as phenol 16 Mass spectrum of compound represented by peak 4 in Figure 7. Identified as p-eresol 53 17 Mass spectrum, of compound represented by peak 6 in Figure 7. Identified as p-ethy1 phenol 54 18 Mass spectrum of compound represented by peak 9 in Figure 7. Identified as skatole 55 19 Mass spectrum of compound represented by peak 15 in Figure 7. Unidentified 56 2 0 Chromatogram of headspace injection of anaerobic unaerated waste 6 2 21 Chromatogram of headspace injection of anaerobic aerated waste 10 minutes after aeration - 62 22 Chromatogram of headspace injection of anaerobic waste at aeration times: 0 minutes, 5 minutes, 15 minutes and 30 minutes. Chromatograms show- decreasing organics in headspace with continued aeration 6 3 vii. LIST OF FIGURES (Continued.) FIGURE 2 3 Chromatograms of headspace of anaerobic waste at times 45 minutes and 60 minutes with chromatogram of blank injection 64 24 Summation of integrated areas for peaks shown in Figure 22 and 23 vs. time 65 2 5 Chromatogram of ether extract of unaerated anaerobic waste, a) acids; b) phenol; c) p~eresol; d) skatole 67 26 Chromatogram of ether extract of anaerobic waste after aeration for 6 0 minutes, a) acids; b) phenol; c) p-cresol; d) skatole 6 8 27 Chromatogram. of ether extract of waste aerated at low pH showing diminished phenol and organic acid peaks, a) acid; b) phenol; c) p-cresol; d) skatole 69 2 8 Plot of equalibrium concentration of a compound (A) over its total concentration. Letters refer to compounds found In waste, a) methanolc acid; b) acetic acid; c) propanoic acid; d) butanoic acid; e) pentanoic acid; g) hydrogen sulfide; . h) phenol; i) p-ethyIphenol; j) p-cresol; k) ammonia; 1) skatole; m) dimethyamine; n) ethylamine; o) indole 71 LIST OF TABLES Summary of compounds identified in v/aste Vapor pressure of selected odorous compounds ix. ACKN GWLE DGEMENTS Sincere thanks is extended to my supervisor Dr. N.K. Builey for his assistance and supervision throughout this endeavour. Gratitude is also extended to Dr. R. Bose, Dr. J. Richards and Dr. R.H. Wright for their helpful advice and for their continued co-operation, and support and to Dr. J. Zahradnik. I also wish to thank Dr. P. Liao whom I consulted on several occasions, Mr. N. Jackson whose machining skills were invaluable in this project and Mrs. E. Stewart who helped to prepare this manuscript. Finally special thanks to Mr. A, Balabanian and Mr. B.A. Stockwell. 1. I. INTRODUCTION Animal production over the past 25 years has experienced a tremendous gain in efficiency due to the trans-lation of scientific research to practical technology in agriculture (Mchren, 1966). Much of this scientific research has concerned itself with determining nutritional require-ments of common livestock animals as well as their breeding habits, social interactions and general handling (Abadia et al. , 1976; Price and Ralston,. 1976; Zaied et al. , 1976 ; Devlin, et al. 19 76). One result of these studies is that today it is possible for more animals to be kept in a limited area of land than ever before. This in turn has generated a variety of aesthetic and practical problems related to maintaining the quality of the environment surrounding these areas. One of the most important problems associated with these modern livestock units is the effective management of wastes. The high concentration of organics in the waste and the staggering volumes produced preclude dumping it into municipal treatment systems (Taiganides and Stroshine, 1971). Some rearing and holding units attempt their own waste control. However, because animal waste is so high in nutrient value, it is frequently land spread. This creates new problems related to air pollution. 2. These problems take on special significance as residential lands begin to infringe on agricultural land. Offensive odors, from some farms, have prompted neighbours to take legal action resulting in curtailed expansion and even the closure, of seme facilities in the United States (Willrich and Miner, 19 71)- Numerous and increasing com-plaints have prompted authorities to attempt to set legal limits on emission of malodors from livestock facilities (Caranci and Wrubleski, 19 74), but unfortunately there is a lack of basic information on the intensity of odors which can be expected from different animal waste management systems. Many of the guidelines in the United States related to odor control in the environment are based on measuring devices such as the seentometer (Huey et al,» 1960). However, to legislate limits based on information obtained from these devices presupposes that the olfactory sense is relatively constant from person to person and that there is an accepted definition of what constitutes an odor nuisance. In fact, the sense of sraell in humans may vary by several orders of magnitude (Silstorff-Pederson, 1964) and what one person considers a nuisance another may not may even detect, Use of devices such as the scentometer can only serve to make this problem more complicated and stall the advent of more rational measuring systems. .Before a solution to the problem of odor legisla-tion is found, a rigorous examination of the quantity and quality of odorants that are produced in wastes and escape into the air must be made. This information must, then be coordinated with accepted average odor detection limits for humans and a working definition made of the condition of odor quality, intensity and duration which can be classified as a "nuisance". As yet there still exists no single widely accepted objective system, for the evaluation of the offensive odors from animal waste and the nuisance they create. There have been,, however, some interesting and relevant attempts at using gas-liquid chromatography as an objective odor evaluation tool (Ifeadi,1975; Miner et al. 1975; Dravnieks, 1971; Schultz et al. 1971; Timmer et al. 1971; Merritt, 1974) and average odor detection limits for many individual compounds are currently being compiled (Stahl, 1974). Although there are many agricultural odor problems in British Columbia, the most pressing problems are related to odors from anaerobically stored and spread swine waste. OBJECTIVES To identify the principle odorous compounds in the liquid phase of the waste from a swine finishing operation. To identify the principle odorous compounds in the head-space above the swine waste. To determine which odorous compounds are significantly reduced in concentration by short term gas stripping of the waste. To investigate whether a shift in waste pll immediately before aeration might be used to increase the effectiveness of aeration for odor control. J I I LITERATURE REVIEW The emission of malodors from animal waste is a problem which can be most .rationally controlled by treating the noxious gases given off or by curbing their initial formation. To realize either of these alternatives, the chemistry of the waste must be known. Fortunately in recent years many investigations into the chemical nature of animal waste have been undertaken. Diebel (1967) identified some volatile constituents of poultry manure and suggested that butyric acid was an important contributor to the odor. Merkel et al. (1969) using various concentration techniques and methods of analysis identified the small organic acids, alcohols, carboriyls, amines ana sulfides in the air above swine waste storage pits, and proposed that the amines, sulfides and thiols were the main contributors to the offensive odor. Burnett (1969) , using pre-column concentration established the. presence of organic acids, sulfides, thiols, diacetyl, ace to inskatole and indole in poultry waste. Using the process of seel active removal based on functional group he was able to conclude that all of these compounds contributed.to the overall odor but that skatole, indole, thiols and sulfides were the main of fenders. Bell (1970) found that the main odorants in liquid poultry manure were the short chain fatty acids. Using a very selective and sensitive technique Uartung et al (1971) specifically looked for carbonyl com-pounds in the atmosphere of sv/ine buildings. They were able to detect and identify ethanal, propanal, butanal, hexanal, acetone, 2-butanone and 3-pentanone. All of these compounds except for ethanal were present in below threshold concen-trations . The authors suggest, however, that they may still contribute to the odor through an additive effect. White et al. (1971) were able to detect the presence of thiols and sulfides in dairy waste and suggested that aeration of the waste removed some of the volatiie sulfur compounds. They also suggested that since the partial pressure of a given amount of hydrogen sulfide was dependent on the pH of the solution in which it was a solute, the pH of the waste was important with respect to its odor. Hammond et al. (19 74) using a gas chromatograph/ mass spectrometer (GC/MS) system coupled with a chromosorb sample con centra tor tentatively identified over 50 constituents of swine house air, although many we re probably much below their odor threshold. The technique of concentration using an absorbant is selective, and because of this it is difficult to extrapolate concentrations of compounds in. the air from their concentrations on the absorbant„ They did suggest, however, that phenol, cresol and various pyrazines were above threshold and probably contributed to the odor. The sulphur compounds were not cited as being main contributors to the odor which, when one considers the findings of others, indicates the variability between sampling stations. Miner et al. (1975) samples over- 30 swine waste storage units and found carboxylie acids,, aldehydes, ketones alcohols, sulfides and thiols in the air. However, concen-trations we re calculated for only the volatile acids and these were found to be be low threshold. Roustan et al. (1977) sampled pig slurries in France and identified methylamine and dimethylamine as being above threshold. Volatile fatty acids were also identified but concentrations were not calculated, and no mention was made as to whether they contributed to the odor. No primary amines, within the limits of the analytical technique were present. McGrath (1977) investigated the odors associated with five pig enterprises in Ireland, using a salting-out technique which enabled him to concentrate organics in the headspace by a factor of many times. With the use of this technique he was able to identify several volatiles which occur in very low concentrations. 8. Schaefer (1U77) investigated the odorous components in pig slurry from, 17 different farms using the technique of solvent extraction coupled with, sniff-port; chromatography. Compounds noted as being odorous were analyzed by mass-spectrometry. Using this technique indole, skatole, phenol, p-cresol and the C^ to Cj. carboxylic acids were all identified in the solution. However, when the ventilation aire of the swine houses was then investigated, many of the compounds could not be detected. The author gives three reasons for this phenomenon: low concentration of compound in the solution, low vapor pressure of the compound, or decomposi-tion of the components in the air. The author believed that hydrogen sulfide and methanethird were decomposing in the air1 and proposed that this was the reason for obtaining high values for their concentrations just above the waste and very low values at any distance from the waste. He thus felt that sulphur compounds were unimportant in the odor at any distance from the site of their production. Components in the manure, identified by the author, which were also present in the ventilation air in significant amounts included phenol, p-cresol and the C„ and Cr carboxylic acids. The finding of the carboxylic acids in .the ventilation air is unusual and implies that the pH of the solution may have been rather low. A low pH v/ould also explain the lack of any amines in the ambient air. Had the pH. been raised, skatole, indole and methyl amine may have been detected., 9 . Lunn and Van De Yyer (1977) used a texax concen-trating system coupled with a 100 mater capillary column for analysis of ambient air in several pig houses. However, they were unable to establish a suitable background blank or to identify any specific compounds. One of the most interesting studies was carried out by Travis and Elliot (1977). They attempted to calculate the concentration of indole and skatole quantitatively, in the air of swine holding buildings. To sample the aire they drew it through portions of cooled ethanol. Based on trapping efficiencies,, which were determined in the laboratory, they were able to conclude that indole and skatole were below a - ] 2 concentration of 2.5 x 10 " g/ml of air (the minimum detection limit for the procedure). Since the odor threshold for _ CI skatole and indole was give at 1 x 10 g/ml of air, the authors concluded that neither contributed to the odor of the waste. As can be seen a great deal of work has been carried out with regard to determining the main odorants in liquid wastes. However, no reports have been found in the literature indicating the pll of the waste is an important factor. Since the partial pressure of many compounds is contingent on pH, this effect should be important. 1999. Another gap in the literature concerns the practical application of these studies. As yet no one has indicated in the literature how the knowledge of the chemical com-position of the waste might he used for the determination of optimal aeration times or for the design of an effective odor supression system. I l l MATERIALS AND METHODS 3.1 Collection of Waste The waste used throughout the study wss col lected from an anaerobic holding tank of a commercial hog finishing operation located about 100 km from the U.B.C. Campus*. The waste consisted of drinking water, washdown water and animal waste held in a 9.14 m x 10.97 m x 1,82 ra open top concrete basin sunk in the ground, The holding tank was fed by an overflow system from two housing barns. The waste was held in the tank between two and six weeks, after which the tanks were pumped out completely and the waste spread on the surrounding land. Samples of the waste were collected from the tank by dipping a one liter metal can into the top 10 cm of the tank and then pouring the collected liquid through' a #2 5 coarse mesh screen into a five liter polyethylene screw top jar, The samples were returned to the Bio-Resource Engineer-ing laboratory immediately after collection and solvent extraction of the waste carried out within two hours of collection. The final samples to be used for analysis, after solvent extraction, were taken from the supernatant of the liquid fraction of the waste only. Sampling took place on the average of once a month from March 1978 to November .1978 * A. Rahn Swine Farm, Cnilliwack, B.C. 3-2 Aqueous Phase Analysis. 3.2.1 Sample preparation. All analytical work was carried out on the liquid phase of the waste only. To ensure this, a sample of the supernatant of the collected waste was passed through a #200 Nytex mesh into a five liter glass Erlynmyer Flask. The flask was then stoppered and sub-samples withdrawn as they we re required. 3.2.2 General extraction and concentration. Chemical analysis of the waste was carried out using the process of solvent extraction coupled with concen-tration by evaporation. The extraction process was begun by drawing a 75 ml sample from the top layer of the five liter storage container, and placing it in a 100 ml Erlynmyer Flask To this, 10 ml of spectral grade diethyl ether was added. The flask was then stoppered and shaken vigorously for one minute and left covered and undisturbed until the two phases separated (approximately five minutes). The top 6-8 ml of ether was then pipetted off, and the procedure repeated twice more with 10 ml portions of ether. All three portions of the ether were then placed into a 25 ml Pierce "Reactifla.sk" fitted with screw-on teflon stopper. To ensure that the ethe was dry, 2 g of magnesium sulfate was added to the extract flask. After 0.5 hours the ether was then pipetted off into an identical flask fitted with a teflon septum. Two Deseret 13. minicatheters with polyethylene tubing and silonized stainless steel needles were then inserted into the septum. Dry ultra-zero helium was passed into one of the catheters, while the other was attached to a drying tube containing anhydrous magnesium sulfate. With the helium flow set at 10 ml/min the ether evaporated over a 12 hour period. 3.2.3 pH selective extraction The solubility of organic acids varies with pH, At pll 9 acidic compounds will be most soluble in aqueous phase while at pH 3 they will be least soluble. Selective extraction of the organic acids in the waste was carried out by first lowering the pH of the waste to 2 and then extracting with ether as outlined above. The ether extract which would then contain most of the organic acids was shaken with distilled water to which 0.Ig of sodium hydroxide had been added. The acids, being very soluble in this solution move from the ether to the water, while other non-acid organics remain in the ether. The pll cf the aqueous phase containing the acids was then lowered (which also lowers their solubility) using dilute hydrochloric acid, and extracted three times with ether. The ether portions were combined and concen-trated to a pale yellow oil. Selective extraction of basic compounds such as amines, could also be achieved using the same procedure and reversing the pH shifts.-3.2.4 Analytical conditions. All gas chromatograms were run on a Perkin-Elmer Sigma 2 gas chromatograph fitted with dual 3.18 mm flash vaporization injectors, temperature dependent flow controllers, dual flame ionization detectors (FID) and single rubidium,/ nitrogen phosphorous detector (NPD). Data acquisition and quantitative analysis was carried out on a Perkin-Elmer Sigma 10 data system coupled to the chromatograph with a Perkin-Elmer 3001 interface. Separation of the neutral and basic extracts was accomplished using a 3.IB mm x 2.4 m stainless steel, 10% OV-101 on 80/100 gas chrom Q column, a 1. 82 m x 3.18 mm 10% OV-lOl 100/120 gas chrom. Q column and a 1.82 m x 3.18 mm 10% Silar 10c 80/100 gas chrom Q stainless steel column. The low pH.extracts were separated on a 1.82 m x 3.18 mm Silar 10c 80/100 C.C.Q. stainless steel column and a 1.82 m x 3.18 mm 15% diethylene glycol succinate 100/120 WAW stainless steel column• The carrier gas, helium, was set at a flow rate of 30 ml/min for all chromatograms. With the FID in operation, the air pressure was adjusted to 2 40 kPa at the chromatograph, while hydrogen was maintained at 183 kPa. These pressures correspond to a flow rate at the FID of 275 ml/min and 43 ml/min, respectively. For NPD operation the airflow was 35 ml/min with hydrogen at 4 ml/min. Temperature programming was used throughout - the analysis; details of which are given on each chromatogram along with injector and dectector temperatures. 15. 3.2.5 Analytical procedures. The volume of the extract concentrates varied from 10 to 20 microliters. Just prior to injection the concentrate was diluted approximately 2:1 with diethyl ether to reduce its viscosity and facilitate its uptake by the syringe. An internal standard was also added to the concentrate with known retention time. All peak times were relative to the standard. Internal standards used included skatole, ethanoi, ether, eugenol, indole and vanillin. Hamilton 10 y 1 glass syringes were used for all injections. Injection volumes ranged from 0.25 y1 to 0.5 y 1. To clean the syringe after each use, approximately 5 ml of acetone and then 5 ml of ether were drawn through the syringe using a vacuum. Analytical standards for amines, phenols, carboxylic acids, aldehydes and sulfur com-pounds were obtained from Polyscience Corporation. The manufacturer and batch number of these and other standards used in the analyses are given in Appendix A. Chromatographic identifications of suspected compounds were based on their retention times matching the retention times of the analytical standards. In each case, two columns were used; one of low polarity and one of higher polarity. In addition to this the analytical standard was also added to the mixture containing + the suspected compound as a final check. Analysis for K and Na ions was carried out on a Jarrel Ash Model 800 Atomic Absorption Spectrcphotometer. 3.2.6 Gas chromatograph/xnass spectrometer analysis. All gas chromatograph/mass spectrometer (GC/MS) analyses were carried out on a Varian MAT Model 111 GC/MS with a Varian data system using locally produced software. The column was a 1.82 m x 2mm 3% glass OV-17 on 80/100 o chromosorb V7AR(HP) . Temperature programming was 8 0 C -275°C at 10°C/min'. Ionization voltage at the mass spectro-- 6 meter was 80 ev. Source pressure was kept at 5 x 10 torr and the source at 2 75°C. Helium carrier gas was set at 27 ml/min. Injection temperature was maintained at 2 00°C throughout the analysis. 3.3 Vapor Phase Analysis. 3.3.1 General setup for headspace analysis. Although the odor of any waste is a function of its dissolved organic compounds, the olfactory epithelium will detect only odorous compounds which are present in the air above the waste at, or higher than threshold concentra-tions. Thus, it is critical to examine which compounds are present in the air above the waste (headspace). This examination is known as headspace analysis and can be carried out by injecting a. portion of the air above a sample of the waste into a chromatograph. A variety of techniques to do this exist. They range from a simple gas tight syringe to a more sophisticated gas sampling valve. Ail headspace analysis discussed in this thesis was accomplished by using a Valco 8 port, medium temperature, 1.59 mm zero volume fittings, 17. stainless steel rotary valve. Two 1.59 mm stainless steel gas sampling loops , one 1.Occ and the other 0.25cc we re connected to the valve using 1.59 mm stainless steel Swagelok fittings (Figure 1). A 25 ml reactiflask fitted with teflon septum acted as the sample vessel. A 1.59 mm x 5.0 cm stainless steel needle bent 12 0° pierced the septum and rested about 2 cm above the base of the flask. A polyethylene Deseret Mincicatheter with stainless needle also pierced the septum (Figure 2). Helium could be delivered through this catheter into the sampling vessel and out through the sampling loops at rates of up to 30 ml/min. The sampling loops were fixed to the valve opposite one another. In this configuration one loop is continuously being flushed with sample while the. other one carries helium through the valve directly to the column (Figure 3) . When the valve lever is turned 12.0° the loops reverse functions. The sample in the one loop will be flushed into the column in a "plug" by the carrier gas, while the other loop will then function as the sampling loop. With this configuration alternate volumes of l.Occ and 0.25cc of sample can be carried onto the column each time the valve is turned. The valve body and sampling loops were mounted directly on the injection heater of the chromatograph and except for the valve lever wrapped entirely'with glasswool. FIGURE 1. Frontal view of gas sampling valve in situ showing a) 0.25 cc sampling loop; b) 1.0 cc sampling loop. 19. FIGURE 2. Frontal view of gas sampling container showing sampling configuration., a,b) sampling loops; c) catheter; d) sampling vessel; e) valve lever MJXtUMII CARRIER HMK-UP I CWR® « to column carrier load loop 2 in) l o o p l sample FIGURE 3. Schematic diagi-am of operation of gas sampling valve. A 1.59 mm x 20 cm stainless steel 0.76 mm inside diameter tube passed through the front of the chromatograph from the valve into the oven and was attached directly to the column using a 1.59 mm x 3.18 mm stainless steel Swagelok Adapter. The valve temperature could be adjusted to remain within 1° C at any temperature from ambient to 200°C. 3.3.2 Analytical conditions. Analysis of the vapor phase was carried out on two columns; a 1. 83 m x 1.59 mm 1.5% XE-6 0 , 1% Ii3PC>4 on 60/80 Carbopak B column and the 1.83 m OV-.lOl column mentioned previously. The first column is specifically designed for ppb analysis of sulphur gases,, while the second is a high temperature general purpose low polarity column. Helium, the carrier gas, was maintained at a 30 ml/min flow rate through the valve and the column. Air and hydrogen were maintained at 275 ml and 43 ml per minute respectively at the FID. The valve body and sampling loops were maintained at 50°C with the detector at 200°C throughout the analysis. Subambient temperature programming was achieved by placing a 500 ml glass beaker containing liquid nitrogen into the oven. Temperature programming data is .recorded on each individual chromatogram. Analytical erases were of the lecture bottle type obtained from Fisher Scientific. Specific data regarding the analytical gases is contained in Appendix A. 21. 3.3.3 Analtyical procedures. The filtered liquid waste (10 ml) was placed in a 25 ml "reactiflask" equipped with teflon septum. The flask was then connected via the stainless needle to the gas samplin valve. Helium gas was passed into the flask via the catheter at a rate of 15 ml/min for the 1.00 cc sample loop and 5 ml/min for the 0.25 cc sample loop. The flask was sampled for 60 and 180 seconds prior to injection of the sample for the large and small loops, respectively. To increase the vapor pressure of the gases dissolved in the liquid, the flask was gently warmed to 35°c immediately before sampling. 3.4 Sniff-Port. In order to ascertain the odor of each peak as it emerged from the chromatograph a sniff-port was constructed. This device consisted of a block of aluminum with dimensions 11.43 cm x 5,08 cm x 1.90 cm fitted, with a 100 watt heater and high temperature thermistor (Figure 4). The block temperature could be controlled and kept constant at a temperature of just above ambient to 450°C. A 3.18 mm hole in the block allowed the passage of a 10.16 x 0.158 cm stainless steel 0.76 mm inside diameter.tube, open at the outside end and fitted to the FID jet mount with an 1.59 mm to 3.18 mm stainless steel Swagelok adapter. The entire block was insulated with 3 cm. of glasswool. The end of the 3.18 mm chromatographic column joined to a 22 . FIGURE 4. Frontal view of sniff-port with insulation removed showing carrier stream exit tube (actual size), a) aluminum block; b) heater; c) carrier gas exit tube; d) flame ionization detector. 23 . stainless steel Swagelok "1" union with 1.59 mm outlets. The sniff-port was connected to one of these outlets by a 15.24 cm x 0,76 mm inside diameter stainless steel tube. The FID was connected to the other outlet of the "T" union through an identical tube. Using this configuration, half of the effluent from the column went to the detector and half went to the sniff-port. A 61 cm tube with an inside diameter of 0.76 mm could be used between the FID and the union if a 10:1 split ratio was desired. Either configuration allowed the operator to assess the odor of each compound as it emerged from the chromatograph. 3.5 Aeration of Samples. 3.5.1 Laboratory scale aeration. In order to be able to study the waste before and after short term aeration, a standard aeration procedure was developed. The procedure consisted of taking 2 50 ml of the filtered waste described in 3.2.1 and pouring it into a one liter Erlynmyer flask. A 5 cm x 1 mm glass capillary tube was then placed into the waste so that it rested on the bottom of the flask. A 3.18 mm Tygon tube carried standard lab air to the capillary. Air was bubbled through the waste at a rate of 150 ml/min for one hour. 3.5.2 Large scale aeration. In order to determine whether rapid gas stripping of the waste would occur in larger waste volumes, a pre-liminary investigation on a pilot plant scale was carried out. Liquid swine waste (700 I) obtained from the U.B.C. barn was put into a 2000 I container, and aerated through rapid agitation, using a variable speed impeller mixer. Sampling of the waste was done serially just prior to aeration and at 5, 15, 30, 45, 60, 120 and 180 minutes after the aerator was started. IV THEORY When extracting any organic compound from a solution for analysis, it is important that all, or a known proportion of the compound be removed during the extraction procedure. In this study a comparison of the effect of waste treatment on the change in quantity of particular compounds in the waste was to be made. It was thus important that the interactions of solubility and pll be taken into account during the extraction and concentrating procedure. 4.1 Extraction Efficiency. An organic compound may exhibit different solubili-ties in different solvents. In a 2-phase system such as ether/water, organic compounds will partition themselves between the ether phase and the water phase in a manner dictated by the polarity of the compound. A non-polar sulstance such as benzene at equilibrium In a water/ether system will par-tition itself in a different ratio than a higher polarity compound such as acetic acid. Thus the efficiency of solvent extraction will vary with the solute being used and the solutes being extracted. In view of this it would be worth considering if there could be any compounds in the waste that the ether would not extract. In a water/ether system, ether would extract the very polar compounds such as the small carboxylic acids and amines least efficiently. Of the carboxylic acids, acetic acid 26 . is one of the most polar. If ether efficiently extracts this from aqueous solution, it would be safe to assume it will ex-tract all less polar compounds that could contribute to the odor as well. For the acids, however, one must consider more than their polarity. Since the weak acids exist in equilibrium with their salts their polarity varies with their state of equilibrium, e.g. CHoCQ0H CH „C00~ + H + J J Equation (1) "is plf dependent. . At high pH more of the acid will be dissociated th an at low pH, In pure water at 2 5 °C the dissociation constant (Ka) for acetic acid is 1.75 x -5 10 , i.e. [H+] [CII3 COO™] 1.75 x 10 = fcir^COOH] (2) At the pH of the waste approximately 99% of the acid exists in the ionized state. In this state it is very soluble in water and virtually insoluble in ether. By extrac-ting the waste at its natural pH the ether could pick up a maximum of 1% of the acid. However, undissociated acetic acid while being very soluble in ether will also be soluble in water. The 1% will be partioned according to its partition coefficient, i.e.; 27. [CII3COOH] H2O Kp = fCir^ COOlil ether (3) From equation (3) it can be seen that at equilibrium the ratio of the concentrations of the solute (acetic acid) in the two phases will be approximately constant no matter what the total concentration. Extraction with one portion of the ether will thus pick up at maximum the fraction dictated by the partition coefficient. More efficient extraction is obtained if the ether is used in smaller portions with several extractions. The amount of material C that remains in the n original solution after n extractions .is described by equation (4) . rv v. n (4) [ V i Cn = C o jKV^Tv-where Co = original concentration of solute (M) n - number of extractions V1 = volume of original solution V2 -- volume of extractant ^ partition coefficient. Equation (4) does not, however, describe accurately the extraction of partially dissociated solutes such as the weak acids. Their behavior is more complex.. As the acid is extracted into each portion of the ether more of it associates to re-establish the equilibrium. Using acetic acid as an example, over 20 extractions would be required to remove 50% of it from solution at pll 1. At a pH of 5 however, four extractions firing about the s£ime result if all other conditions remain identical. Thus, shifts in pH can be used to enhance the extraction procedure for acids and for basic compounds such as amines. It should also be noted that as the number of carbons in the aliphatic acids increases their partition coefficient changes according to: c 2 > c 3 > C 4 > c 5 > c 6 > C 7. By C^^ the aliphatic acids are virtually insoluble in water and soluble in all proportions in ether (Morrison and Boyd, 1.967) .. For organic compounds of concern other than the acids or bases, the partition coefficient relative to the water/ether system is sufficiently small that it may be assumed that extraction is virtually 100% efficient. (Robertson.and Jacobs,1962)A wide spectrum extraction of the waste can be carried out by extracting the liquid at pll 4 and pH 10 and combining the ether extracts. 4.2 Effect of drying agents. When the ether comes into contact with the aqueous solution it becomes saturated with water. If the ether extract is then concentrated by evaporation what remains is a turbid oily liquid. If this liquid is then analyzed, using gas chromatography, it is found to contain almost no organic acids; If magnesium sulfate is added to the ether,a reaction 2 9 . takes place which can be described in equation (5). MqSO, + H00 MgSO. . H„0 (5) 4 2 «- 4 • 2 and most of the water is removed. When the treated ether is then concentrated and the spectra run it is found to contain a high concentration of organic acids. For this reason all extractions were done using dried ether. A possible explanation for this phenomenon is: as the wet ether is concentrated the organic acids form their sodium and potassium salts. When all the ether/'water is removed these salts would be insoluble in the oil and precipitate out. To determine if this was possible the wet ether extract was •itself extracted with distilled water and the water analyzed for the presence of sodium and potassium ions. The result 4- + snowed that Na and K were in excess of 25 mg/liter (ether) » while a water extract of the MgSOA dried ether gave almost no reading for these ions. Thus the Na+ and K+ ions are in the extract. However, this is a necessary but not sufficient con-dition for this hypothesis. The phenomenon needs further investigation. 4.3 Concentration Effects Although very volatile compounds can be picked up by the ether extraction procedure, they will be lost during subsequent concentration. Compounds such as hydrogen sulfide (bp - 60.7° C), methanethiol (bp - 6.2° C), ammonia (hp - 33° C) methylamine (bp - 7.5° C) ethylamine (bp - 7.5° C) 30. dimethyl amine (bp •- 17°C, t rime thy I amine (bp ~ 3°C, forrnal-o o dehyde (bp - 21 C), acetaldehyde (bp - 20 C) would all eva-porate rapidly. Analysis for these compounds is best done by the headspace technique described in Section 3.3. More marginal compounds (e.g. the small aldehydes, certain amines, small sulfur compounds) which are liquids at 25°C but have high vapor pressure may or may not be concentrated by this technique. It should Ie assumed, however, that since the ether is totally evaporated during the concentration process, any compound with a vapor pressure similar to or greater than that of ether (435 mm at 25°C) will be lost. A chromatogram of the dried ether extract of dis-tilled water gave a flat response indicating that the experi-mental procedure does not introduce extraneous peaks. 4.4 PH effect The aqueous phase of the waste is an extremely complex system, containing probably hundreds of compounds. As such, there exist many possible complex interactions within the liquid. The fact that this liquid is also rich in bacteria which metabolize and excrete various organic compounds makes the system dynamic as well. Any analysis of waste this complex can only hope to describe the waste as it was at that particular time. Dissolved compounds in the waste are in delicate balance with the particular bacteria population, the ionic 31. strength, the temperature of the waste, the amount of oxygen dissolved in it and the pH. of these parameters, pH has the greatest potential for causing an immediate change in the chemistry of the waste. While the acid/base chemistry of compounds in the aqueous waste may be slightly modified due to various interactions they will, for the large part, behave as though they were dissolved in pure water and any conclusions based on the use of pure water as a solvent will hold for the waste. Virtually all of the organic compounds which occur in the waste can exist in an ionized and unionized form (Stecher, 1968, Allinger et al., 1971) e.g.: 32 . For most of these compounds the degree of dissocia-tion is very small and virtually independent of pH, and we generally think of them in terms of their unionized forms. However, for certain compounds, the degree of ionization is contingent on the pH of the solution in which they are solutes. In the ionic form a compound will have essentially no vapor pressure and therefore no odor. The pH of the solvent is thus very important in terms of the solutes' odor. At pH 7 virtually all of the small organic acids dissolved in water will exist in their ionic form and will have little or no odor. However, as the pH is 1owe red more of the associated acid forms and there will be an increase in the odor. The shape of the dissociation curve is expressed by the Henderson-liasselbalch equation, which Is a logarithmic transformation of the expression for the dissociation constant (Lehninger, 19 71) . TT „ , , [proton acceptor] ,„, pH - pKa + log S r T J (9) ^ 3 [proton donor] Equation (9) makes it possible to calculate the molar ratio of proton donor and proton acceptor given the pH and pKa. Thus, it can been seen, using this equation that a small shift in pl-l can considerably change the acid-base equilibria. Recalling to mind that the ionic form of a compound will 33. have no odor, it can be seen that the Henderson-Hasselbalch equation is applicable to predicting the odor potential of certain compounds. Using the acids as an example, a shift of 2. pll units can result in an increase in the observed odor from almost nil to overwhelming. The situation for the bases is analogous to that of the acids. Compounds such as ammonia, skatole, indole and small primary or secondary amines will all exist in a pro-ton a ted or unprotonated form depending on the pH of the solvent. At a pH of 7 ammonia with a pKa of 9.25 will be primarily in the ionic form with little vapor pressure. As the pH is raised more will be converted to the neutral form. At pll 10., 84.9% v/ill be in this neutral form and, consequently ammonia will begin to be evolved from the waste. This situation, however, v/ill be predictably less objectionable than when the pli is lowered and the acids begin to come off, simply because the acids have a more objectionable odor than the amines. Other compounds not specifically defined to be acids or bases are also affected, by pll. Phenol, for example, dissolved in water, will approach maximum vapor pressure as the pH is lowered from 10. At oil above 11 it will be almost completely in the dissociated form (and as such will be odorless) . The reason for phenols oil dependence is that it acts as a very weak acid (pKa 9.8 9). 34. Hydrogen sulfide and methanethiol, both gases at 25°C act as acids in aqueous solutions and are are also affected by pH. e.g.: pk 7,04 pk 11.96 H„S -> SH~ + H+ ->- S= + H+ (10) / •*• H^S with a pKa of 7.04 wi 11 exist in water at pH 7 in a half ionized state (Chemical Rubber Company, 1969). If the pH is dropped by just one unit to 6, 92% of the H^S will be in the protonated form. If the pH is raised by one unit to 8, only 10% will be in this form. According to Henry's law the amount of t^S above the solution will be dependent on the amount of H?S in the solution (Barber and McQuitty, 1974), i.e.: [H0S ] = - [H„S] aq. (11) z ct / where a is the absorption coefficient. Any change in a or [Il^ S] will cause a change in [H^S] gas. Since [H2S ] aq. is affected signif icantly by pll, [ H ^  8 ] gas will also be affected. Methanethiol acts in a similar manner: [CH3SH] gas =- ~ [CI^ SII] aq. (12) From equation (11) it can bo sqen that as the pH is lowered more of the compound will be in the associated form and consequently there will, be more in the air above the liquid. Compounds also exist which are not greatly affected by pH. Aldehydes, ketones and hydrocarbons have such small ionization constant that their chemistry can be considered independent of pil. As such their odor will .also be independent of pH. 3b . V. RESULTS AND DISCUSSION 5.1 Sample collection and preservation In waste research samples are not normally analyzed on the same day as collection. The'samples are generally stored at 0°C with additional chemical treatment, if required, depending on the particular characteristic to be measured (Standard Methods, 1975). It was felt that althoucih little change would occur in the quality and quantity of odorous compounds in the swine waste within a 'few hours after collection, sample freezing or storage at 0°C for several days might result in significant change. To determine whether immediate extraction of the waste was required, ether extracts were taken from the waste samples before and after storage at 0°C for seven days. Chromatograms of the ether extracts proved to be qualitatively very different. No attempt was made to analyze the differences or determine the time course of the change. But, because of the results, all extractions of the waste samples were carried out on the same day as collection. To determine whether or not the extract concentrate might be more stable in storage than the liquid waste, a sample of the extract was analyzed by chromatograph immediately after concentration and again after storage 37. at 0°C for 6 days,. Mo sognificant qualitative or quantitative changes were observed when the chromatograms were studied (Figures 5 and 6). Based on these findings storage of the extract rather than the waste is preferable if analysis is to be delayed. All analysis of the waste extract was done immediately after concentration, with the exception of the sample stored for one week (Figure 6). 5.2 -Identification of compounds in waste. 5.2.1 Selection of compounds for identification. Based on previous reports (Hammond et al., 19 74; Schaefer, 19 77) and initial results it was evident that many organic compounds could be found in an extract of swine waste (Figure 7). This study was specifically interested in those compounds with factors influencing the odor of the waste as a whole. In this regard the olfactory profile of the waste was important. The sniff port in parallel with the FID allowed a comparison of which organic compounds were odorous among all the compounds separated and analyzed by the chromatography Thus an olfactory assessment of each peak can be generated (Figures 8 and 9). The results are similar to those reported by Hammond et al., (1974). By using this procedure it was, determined that many of the compounds in the extract were either non-odorous or slightly pleasant smelling. Whether or not these com-pounds contribute in some synergistic or other way to the odor has not been determined. SILAR 10c 6fT, 'C - 250°C S 6°C/MIN, DETECTOR 293°C INJECTCfi 1SD°C romatogram of ether extract concentrate 24 hours ter collection of vzaste. U) CO n SILAR 10E 5FT, 80°C - 250°C 3 6°C/MINI DETECTOR 29J°C lronatogram of ether concentrate after storage fo days at 0°C. FIGURE 7. Chromatogram of ether extract concentrate of waste. Numbered peaks represent compounds in the waste significant in terms of their odor. O H Q G a bi o H-ft fi 0 B o Q> a. rt 0 O n '-Q H SH p> w 3 w 0) 0 cn l-tl K> (D ro rt IJ" rt CO hi O Mi a> X (D r+ n> H o (D tr a r+ ts <D o 0 w • O CD P rt H 0> rf fD 0 Hi .< (5 w r+ w STRONG ORGANIC ACID, ALDEHYDE BLFRMT RUBBER WEAK FHEFOL STRONG PHENOL • SLIGHT CHOKING STRONG PHENOL C"> BURNT RUBBER SLIGHT PHEN3L CITRIC ACID DIALLYL SULFIDE >SWEET ESTER C SKATOLE "^ RUBBER SWEET ESTER JG FFI S3 S BURNT ESTER m rl o°i—• n o o r=f > 'INSECT REPELLENT WEAK RLEBER VERY WEAK ALDEHYDE Q 3 VERY WEAK VERY WEAK 'TV FIGURE 9. Chromatogram of ether extract of low pH waste with odor assessment of each peak. >t> K) 43. The remaining compounds had from mild to strongly unpleasant odors and were distributed randomly throughout the chromatogram. Attempts were made by a variety of techniques to identify peaks or qrouos of peaks designated in Figure 7 by numbers (1-16). In many cases the odor of the comoound gave some clue to its identity, and could also be used as supportive evidence when' its identity was established by other methods, 5.2.2 Identification based on column retention time. Column retention time, on a single column, does not give an absolute proof for the identity of any sinale substance. Because of this, separation of the same sample on another column with different polarity is essential. Overlapping of peaks from standard compound and sample on both columns at various temperatures represents a far more convineina proof than on one column only. However, it can be used as an absolute proof in the negative sense. In this case if the chromatogram of the mixture of the original sample and the added standard show an additional peak not present in the original chromatogram, the compound in question is not the same as the standard. The compounds in Figure 7 designated by the .number 1 were suspected because of their odor, to be acids. With this in mind, an acid extraction procedure was carried out 44. and a chromatogram (Silar 10c) run of the concentrate. Figure 10 shows that the concentrate consists of at least six compounds. Figure 11 is a chromatogram of a mixture of ethanoic, propanoic, butanoic, pentanoic, hexanoic and heptanoic acid run on the same column as the sample. Retention times are identical. When the sample was run on a second more polar column (Figure 12) six peaks were also observed with the same retention times as the standards (Figure 13). Because the acid extract sample appeared to be composed of ethanoic, propanoic, butanoic, iso-butyric pentanoic and hexanoic acids, analytical standard acids were added to the sample and a chromatogram run on Silar 10c (Figure 14) . There we re no additional peaks. Thus based on the retention times of the samples, it appears as though the acid extract sample was composed of the above mentioned acids. Merkei et al. (1969) we re unable to detect the organic acids in the air above storage pits containing liquid hog waste. However, this is no doubt due to the fact that the pH of the waste was above 8.0. The presence of these acids is, however, in keeping with Hammond et al. (197 4) who identified ethanoic, propanoic, and butanoic acids as being the major constitutents in the headspace above swine waste along with pentanoic, hexanoic and methylpentanoic acids as minor components. FIGURE 10. Chrcraatocrram of ether extract of low nil v/aste on Silar 10c column. SILAR 10c 6fT, 5D°C - 2IJO°C 3 8°C/MIN. DETECTOR 275°C INJECTOR 150°C Chromatogram of a mixture of ethanoic, propanoic, butanoic, pentanoic, hexanoic and heptanoic acids in ether on Silar 10c column. BEGS 6FT. DETECTOR 275°C INJECTOR 150°C 50°0 185°C 3 8°C/MINUTE Chromatogram of ether extract of low pH waste on diethylene glycol succinate (DEGS) column. F I G U R E 1 3 , ESS 6FT, DETECTOR 275°C IMJECTOR 150°C 50°C- 185°C a 8°C/MIN Chromatogram of ethanoic, propanoic, butanoic, pentanoic, hexanoic and heptanoic acids in ether on DEGS col with ethanoic, propanoic, butanoic, pentanoic and hexanoic acids added, Silar 10c column. 50. Roustan et al. (19 77) using a similar solvent extrac-tion procedure also identified these same acids as being in significant concentration in the waste. 5.2.3 GC/MS analysis. Of all the techniques for identi fying a complex mixture of compounds the GC/MS is the most useful. The only criteria to obtaining' satisfactory results from the instrument are that there must be enough of each peak to enable a satis-factory mass spectrum, to be run, and the peaks must be well resolved. Mass spectra v.ere obtained for the compounds represented by peaks at 2,4,6,9, and 15 in Figure 7. By comparison to tabled mass spectra data it was determined that these compounds we re phenol, p-cresol, ethyl phenol, skatole and an unknown respectively (Figures 15--19) . The compound designated by peak (15) could not be identified. Ho tabled data corresponded to it. The most striking feature of its spectra is- the successive loss of 13 methylene groups. This indicates that the compound is probably a long chain carbon compound rather than a cyclic aromatic one. Other researchers (Hammond et al., 1974; Merkel et al., 1969) have also identified skatole, p-cresol and phenol in the headsoace of stored swine waste. Hammond et al., (1974) also identi fied p-ethy1 phenol as being a constituent of the waste. Thus of the original 16 major odorous peaks in Figure 7, identification of five has been possible. 51, TABLE 1 Peak Compound ~~ 1 ethanoic acid propanoic acid butanoic acid pentanoic acid hex-anoi c acid 2-methyI propanoic acid 2 hydroxybenzene (phelol) 4 p-hydroxytoIvene (p-cresoD 6 g-hydroxy ohenyl ethane (p-ethyl phenol) 9 3-methyl indole (skatole) •—-»1 „ _LLLU FIGURE 15, W e 100 h a s s spectrum of compound represented by Figure 7. Identified as phenol. peak 2 in tn to JUl j. ji..*.*,._—.— We 10) FIGURE 16 Mass spectrum of compound represented by peak 4 in Figure 7. Identified as p-eresol. Co ik II.. liii^ j M/e 100 FIGURE 17. Mass spectrum of compound represented by pealc 6 in Figure 7. Identified as p-ethy1 ohenol. ui J L j i L Jlii. M/e ICO FIGURE 18. Mass spectrum of compound represented by peak 9 in Figure 7. Identified as skatole. cn cn M/e IGURE 19. Mass spectrum of compound represented by peak 15 in Figure 7. Unidentified. 57. 5.3 Odor potential of compounds identified in waste. Compounds designated by peaks at 3,5,7,8,10,11,12, 13,14,16 in Figure 7 could not be identified due to low con-centration, or insufficient resolution, or both. Because odor thresholds vary so much from one compound to another (Appendix B) it does not follow that the odorous compounds of greatest concentration v/ill be the main offenders in the waste. There are many compounds in the waste v/hich cannot be resolved and/or detected with the present equipment, but may contribute to the odor. While skatole, phenol, ethyl-phenol and p-cresol have all been identified in the liquid phase of the waste and contribute signficantly to its odor their combined odors do not account for all of its offensive nature. 5.4 Quantitation of compounds. In order to provide basic information for use in design of odor control systems, it would be helpful to know not only v/hich compounds are present but also the quantities of those compounds which require treatment or removal. To use the chromatograms in a quantitative way, one must know the effectiveness of the extraction and concen-tration procedures. Very volatile compounds or compounds with a high solubility in water are more difficult to assess quantitatively as their partition coefficients must first be accurately determined. However, compounds such, as skatole are not volatile (V.P. << 1 mm Hg at 2 5°C) nor very soluble in water. They are however very soluble in ether. For this case the ether extraction and concentration procedure can be assumed to be 100% efficient. An estimate of the concen-tration of skatole was obtained by weighing the dried ether extract of a known volume of waste and determining, by integration of the peaks, the portion of the extract which consists of skatole. When this was done it was found that the liquid contained approximately 9 mg/1 of skatole. This value is higher than the 4.03 mg/1 reported for anaerobic swine manure by Travis et al. (1977), but great variation in the concentration of all organics would le expected from farm to farm because of differences in such things as age of waste, type of operation and type of feed. Phenol, creso.l, and ethyl phenol all have some slight solubility in II20 and therefore the extraction proce-dure will be less than 100% efficient. Nevertheless, since their vapor pressures are very low, the amount of compound found in the extract will represent a minimum concentration in the original solution based on the above extraction pro-cedure. Keeping this in mind, it was found that the concen-trations of phenol, cresol and ethyl phenol in the waste were 91 mg/1, 73 mg/1 and 1.6 mg/1, respectively. Due to 59 „ the higher volatilities and varying solubilities of the acids and small amines this technique is less straightforward when measuring their concentrations. However, concentrations for the acids, in particular, can be obtained if their partition coefficient is known and if the sample has been preserved ly raising its pH to 7 or higher. 5.5 Effect of pll on odor of waste. It was observed when using freshly collected waste sampled from the vessel described in Section I(i) that If the pH was lowered from the natural state (pll 7) to pH. 2 , the odor increased dramatically in intensity, and changed in quality to a much- more offensive nature. If the pH were raised to 11, a strong ammonia odor resulted. However, unlike the odor at low pH which persisted the ammonia odor was transitory, and the remaining waste was almost odorless. When the waste was extracted with ether at pH 7, the waste became odorless. If the pll was then lowered the waste took on a very offensive odor indicating that at pH 7 ether does not extract all odorous compounds. If, however, the waste was extracted with ether at both pl-l 3 and pK 11, it was found to be completely odorless from pH 3 to pH 11. Although ethanoic, propanoic,"butanoic, pentanoic and hexanoic acids have all been identified as being in significant concentration in the liquid phase of the waste, 60. it is questionable whether under normal conditions they contribute significantly to its odor. At the natural pll of the waste f> 7-8) these acids exist mostly in an ionized state and therefore their concentration in the headspace should be far below detection threshold. If, as mentioned previously, the pH of the waste is lowered to 5, the volatility of the acids increases and thei concentration in the headspace above the waste is commensura tly Increased, A shift in pH from 8 to 5 will increase the concentration of acids in the headspace by a factor of several hundred. This, coupled with the fact that their odor threshold detection limits are very low (Appendix B) and their odor extremely offensive indicates that the acids in the liquid waste can provide significant contribution to the odor at low pH„ This effect of pH on the resulting odor should be given important consideration when evaluating possible waste treatment systems, chemical additives to waste and possible pll shifts when the waste is added to acid soils. 61. VI AERATION OF WASTE 6.1 Aerating effect on headspace analysis. Various authors (Merkel et al., 1969; Hammond et al., 19 74) have reported that although freshly aerated swine waste was much less odorous than non-aerated anaerobic waste, the aerated waste still had an unpleasant "medicinal" odor associated with It which lingered for a considerable time and was not greatly affected by further aeration. This phenomenon was investigated using combination aqueous phase and headspace analyses, The headspace analysis of a sample of the anaerobic waste indicated that the headspace contained at least four compounds (Figure 20). Using relative retention times, lead acetate paper, and the odor of these compounds it was determined that hydrogen sulfide and methanethiol contributed significantly to the overall odor of the unaerated , anaerobic swine waste The waste was then aerated as described in Section 3.5.1 and the headspace analyzed before and after aeration. Within 10 minutes of aeration all the peaks in the chromato-gram, including methanethiol, were undetectable (Figure 21). Headspace analysis was then carried out sequentially on the large scale aeration experiment described in Section 3.5.2 at times, t = 0, t -= 5, t = 15, t = 30, t = 45, t = 60, t = 120 and t = 180 minutes (Figures 22,23). At t = 0 at least three peaks are clearly resolvable, one of which is 0.25 CC INJECTION M)°C ISOTHERMAL OV 101 6 FT, DETECTOR 200°C VALVE BODY SD°C FIGURE 20. Chromatogram of headspace injection of anaerobic unaerated waste. FIGURE 21. Chromatogram of headspace injection of anaerobic aerated waste 10 minutes after aeration. 1 1= 0 MIN, 1 CC UOGP FIGURE 22, R= 0 MIN, 0,25 cc LOOP T= 5 MIN. 1 CC LOOP T= 5MIN 0.25 LOOP •M-0V 101 6 F T , ATTENUATION 7=15 MIN. 1 CC LOOP T=15 MIN 0.25 LOOP T= 5J MIN 0,25 LOOP Chroraatogram of headspace injection of anaerobic waste aeration times: 0 minutes, 5 minutes, 15 minutes and 30 minutes. Chromatograms show decreasing orqanics in headspace with continued aeration. CTl U> OV IOI 6 F T , ATTENUATION 0 ICC LOOP 0,25 LOOP BLWK INJECTION - 6 0 M I N . 0.25 LOOP FIGURE 23. Chromatograms of headspace of anaerobic waste at times 45 minutes and 60 minutes with chromatogram of blank injection. FIGURE 24. Summation of integrated areas for peaks shown in figure 22 and 23, vs. time, FIGURE 25, Chromatogram of ether extract of unaerated anaerobic vaste, a) acids; b) phenol; c) p-cresol; d) skatole. cr> C-! 67 „ methanethiol. Figure 24 is a plot of the summation of the integrated areas of all the peaks in the headspace chroma-tograms (Figure 2.2, 23) vs. time. By t = 4 5 minutes the concentration of organics in the headspace had been reduced significantly to a constant, much lower level. During this time the odor of the waste changed from very strong and objectionable to weak and unpleasantly "medicinal" in nature. A similar rapid decrease from a strong objectionable odor to a constant weak background has also been reported elsewhere for anaerobic liquid swine waste after short term aeration (D. Phillips, II.Sc thesis in preparation) Evidently these strong objectionable volatile gases are being sparged from the liquid waste as it is aerated. When the waste is quiescent, all the comnounds that result from anaerobic decomposition by bacteria will tend to build up in concentration. When the waste Is aerated the rapid transfer of the compounds from the liquid phase to the gas sparging stream results in a removal of those compounds from the waste. A very intense odor results in the gas stream. Since the compounds cannot be generated by the bacteria as quickly as they are removed, the odor level in the gas stream and subsequently in the liquid phase drops rapidly with time. 6.2 Aeration effect on liquid phase analysis. In an effort to determine why aeration of the waste, to reduce its odor, is effective only to a certain point, 250°C a 6°C/HIN, Chromatogram of ether extract of anaerobic waste after aeration for 60 minutes, a) acids; b) phenol, c) p-cresol d) skatole, O" cc J ov 101 6FT, arc - SQ°c a 6°c/MIN. DETECTOR 2CJj°C INJECTOR 200°C FIGURE 27, Chromatogram of ether extract of waste aerated at low pll showing diminished phenol and organic acid-peaks, a) acid; b) phenol; c) p-cresol; d) skatole, VD 70 „ the liquid phase was investigated using the ether extract procedure. During the course of these experiments, skatole, which was previously determined to be unaffected by aeration, was used as a quantitative standard. The chromatograms which are essentially alike before and after aeration indicate that aeration has little or no affect on the compounds dissolved in the waste which are detectable by the ether-extraction procedure (Figures 25 and 26). Compounds such as phenol, p-cresol, skatole and, p-ethyphenol no doubt con-tribute to the odor of the waste before and after aeration. Before aeration, however, the odor of these compounds is masked by the odor of the much stronger, more volatile sulfur gases. When these volatile sulfur gases are sparged off what remains are the less volatile phenolic smelling compounds which are aeration stable. If the pH of the waste is lowered, and then aerated, the organic acids are removed by sparging and reduced to undetectable levels (Figures 25 and 27), the phenol peak Is considerably lowered and an unknown compound, with a phenolic like odor, is completely eliminated. If the pH of the waste is lowered prior to aeration, the volatile gases come off so rapidly that the waste foams. If the pH is then raised back to 7 it is found that the waste has been considerably reduced in odor but still has a "medicinal" quality. This reduction in unpleasant odor after the release of compounds which are aeration labile at low FIGURE 2 8. Plot of equalibrium concentration of a compound (A) over its total concentration. Letters refer to compounds found in v/aste, a) methanoic acid; b) acetic acid; c) propanoic acid; d) butanoic acid; e) pentanoic acid; g) hydrogen sulfide; h) phenol; i) p-ethylphenol; j) p-cresol; k) ammonia; 1) skatole; m) dimethyamine; n) ethvlamine; o) indole. -j t_i pll, indicates that the acids, though low in concentration in the headspace may have sufficiently low odor thresholds, that they still contribute to the odor. 6.3 General Discussion. The variation that exists both in the odor of liquid swine waste and its susceptibility to aeration with varying pH can be more fully explained (Figure 28), As discussed previously, many organic compounds exist in an ionized or neutral state depending on the pH of the solution in which they are solutes. Figure 28 is a plot of the equilibrium concentration of the neutral form of a com-pound over its total, concentration vs. pH. Since only the neutral form of a compound has a vapor pressure the concentra tion of compound in the headspace will also vary with pH. If a compound obeys Henry's lav/ and its total concentration in the aqueous phase is known, its absolute concentration in the headspace , at equilibrium for a given pH can be calculated by multiplying the fraction , obtained from Figure 28, by the concentration obtained from Henry's Lav/, A more general expression describing concentration in vapor phase f o r any compound whose degree of i o n i z a t i o n varies significantly with pll providing the compound obeys Henry's Lav/, can be obtained by algebraically modifying the He n de r s on - II as s e lb a 1 en equation (9) and combining it with Henry's Law, equation ( 1 1 ) . The resulting expression: 73 „ r T) -I — i f A ] X ~ -vapor ~ a aqueous ' ^ + ^gpil-pKa (13) gives the absolute headspace concentration for a compound at equilibrium with its vapor, if its pKa, the proportion-ality constant (a) , its absolute concentration and the pll of the solution in which it is dissolved is known. Since the odor of a compound will generally increase as its concentra-tion in the air increases, this equation also expresses odor as a function of pH. Thus, again referring to Figure 2 8 it can be seen that at a pll of 7 the acids (a-f) will exist almost completely in the ionized form and as such will exhibit only a small fraction of their maximum possible vapor pressure and consequently only a fraction of their maximum possible odor. When the pH is lowered to below 6, the volatility of the acids increases resulting in an increase in their odor. Similarly at a pH of 7 the amines will also be fully ionized and contribute little to the odor. However, unlike the acids, as the pH is raised the amines will be converted to their very odorous neutral forms. Hydrogen sulfide will have a considerable vapor pressure and odor in the pH 7 range. Since its pKa is also in this range (7.03) its vapor pressure and odor will change very dramatically with small pH shifts. Because of the strong unpleasant odor associated with this compound, this fact is quit e i rap o r t an t. 74 „ Compounds such as the phenols will display maximum vapor pressure and consequently maximum odor at the normal pll of the waste. In view of this it is not surprising to find that the raw waste has a characteristic phenolic odor, once the more odorous sulfur compounds have been removed. Since a compound cannot be gas stripped from solution in an ionized state,, Figure 2 8 can also be used to predict the effectiveness of aeration at varying pll. At pi! 7 aeration will be most effective on those compounds which are least ionized. Referring again to Figure 28, it can be seen that aeration at natural pH will affect only hydrogen sulfide and the phenols. The acids and amines at this pH are almost completely ionized and as such least susceptible to aeration. As the pll of the waste is lowered the acids become less ionized and are more efficiently removed from solution. Another factor to be taken into consideration when aerating, is the volatility of the various compounds in solution. Ethyl-phenol at pil 7 will exist almost completely in the neutral form and as such will be displaying maximum volatility. However, because this volatility is so low (Table 2) aeration is, in fact, not" a very efficient method for its removal. Hydrogen sulfide on the other hand can be stripped from solution at even relatively high pH. The reason for this is that, equation (14) II S £ HS~ + Ii+ (]-4) TABLE 2. Vapor pressures of selected odorous compounds. Compound Methanoic acid (a)* Ethanoic acid (b) Propanoic acid (c) Butanoic acid (d) Pentanoic acid (e) Ilexanoic acid (f) Hydrogen sulfide (g) Phenol (ii) p-ethyl phenol (i) p-cresol (j) Ammonia (K) Skatole (1) Dimethy1amine (m) Ethylamine (n) Indole (o) Vapor pressure 1 mm Kg at - 2 0°C - 17°C -- 4.6°C 25°C 4 2 °C 71°C - 134°C 40°C 59°C 5 2°C - 109 °C 95°C - 8 8°C - 82°C Not knov/n * Letters refer to vapor pressure vs pll curves in Figure 2. 8 6 . expresses an equilibrium reaction. According to le Chateliers principle if one side of the reaction is changed to disturb the equilibrium the other side will change accordingly, in order to re-establish it. Thus, if neutral hydrogen sulfide is removed from solution, more of the ionized form will associate. This equilibrium reaction can be considered here, to be instantaneous making virtually all of the compound available for volatilization during stripping Thus, the speed at which the total amount of hydrogen sulfide is sparged from solution will be principally a function of its volatility and relatively independent of pll. Based on this information, it is now obvious why aeration of waste holding tanks is able to reduce the offensiveness and the intensity of the waste odors, but is not able to completely eliminate the odors (D. Phillips). The long term lingering odor observed after short term aeration (2-4-hours) is due to the very slow release of the lower vapor pressure compounds which are relatively unaffected by aeration. Additional short term aeration (up to 24 hrs) will have little effect on sulsequent odor levels. The immediate decrease in the offensiveness of the odor of the waste is a result of the shift from sulfur compounds such as methanthiol and hydrogen sulfide to the less offensive phenols. 77 „ Acid treatment of the waste before aeration would considerably improve the effectiveness. Based on our results, the treatment of this highly odorous sparging stream with a di lute solution of dodium hydroxide v/as should remove most of the odorous gases. Activated carbon scrubbers as proposed by many researchers might not be as effective since carbons affinity for hydrogen sulfide is relatively poor. 2067 „ VII CONCLUSIONS 1) Odorous compounds in high concentration in the liquid phase of the waste have been identified as: p - cresol, p-ethylphenol, phenol., skatole, acetic acid, propanoic acid, butanoic acid, iso-butyric acid, pentanoic acid and hexanoic acid. 2) Odorous compounds in high concentration in the vapor phase above the waste have been identified as: hydrogen sulfide and methanethiol. 3) Short term gas stripping of anaerobic swine waste reduces the concentration of the very volatile compounds found in the waste such as methanethiol and hydrogen sulfide. 4) A shift in the pH of the waste to 3 prior to aeration greatly enhances the effectiveness of aeration in removing volatile compounds with low pKa's such as the sulfides and low molecular weight organic acids, while at the same time decreasing the effectiveness of aeration in removing volatile high pKa compounds such as ammonia and methylamine. Since the low pKa com-pounds are generally the most offensive, lowering the pll prior to aeration increases the overall effective-ness of aeration v with respect to odor control. SUGGESTIONS FOR FURTHER STUDY Although this thesis isolated and studied certain problems associated with control and analysis of odors arising from farm animal waste, many problems still remain. One such problem is whether pll manipulation of waste is practical on a farm level. If the pH is lowered and the waste aerated, very odorous compounds come off rapidly. Obviously some way of treating or containing the odors re-leased would be needed. If the pli is raised, however, the odor is significantly reduced without aeration, but then, the volatile amines valuable for their nitrogen content would be lost. Further study is required before the use of aeration, accompanied by a pll shift, can be recommended for farm use, /mother avenue for investigation involves treatment of the waste using chemical oxidants. Compounds such as potassium permanganate and hydrogen peroxide have been shown to significantly reduce the odor from certain types of wastes. Exactly how these compounds reduce odor, whether their effectiveness is contingent on pH, and whether they act indiscrimantley or on particular compounds is not known. Tne methods, for analysis of waste developed in this thesis how-ever should lend themselves well to the study of the problem and optimization of this technique of odor control. 80. APPENDIX A MATERIALS AMD CHEMICAL SUPPLIE S . - - — Compound M anuf acturer Lot # Acetic acid Mailinckrodt (USP) AHV 2 505 Propanoic acid Polyscience Kit No. 65a Butanoic, acid Polyscience Kit No. 65a Iso-butanoic acid M C B* 3G 26 Pentanoic acid Polyscience Kit No. 65a Hexanoic acid Polyscience Kit No. 65a Heptanoic acid Polyscience Kit No. 65a Carbon tetrachloride M C B Spectral 2112 6 Methanol Fisher Spectral 7G13 Diethyl ether Burdick & Jackson Spectral AC47 * Skatole M C B A16 Acetone Fisher ACS 7 415 14 Coumarin M C B D3F07 Indole Eastman B6 A Tryptamine M C B 4F17 Cumene M C B A9H13 Hexane M C B 12 GO 7 Magnesium sulphate M C B 2 JOZ Sodium sulfate Mailinck rodt 1IAM Potassium bromide Mallinckrodt WE PA Acrolein M C B 4II0 7 Prop anal Polyscience Kit No. 45c Butanal Polyscience Kit No. 45c Iso-butanal Polyscience Kit No. 45c Matheson Coleman & Bell 1 Compound Pentanal Hexanal Phenol o-Cresol m-Cresol p-Cresol 0 - e thy Iphen o 1 p-ethyIphen o1 n-propyl mercaptan Iso-butyl mercapten n-butyl mercapten Dlallyl sulfide Diethylamine Di-n-propylamine Di-n-butylamine Trie thyamine Hydrogen sulfide Methyl mercapten Methyl sulfide Helium Hydrogen Air Manufacturer Polyscienee Polyscience Polyscience Polyscience Polyscience Polyscienoe Polyscience Polyscience Polyscience Polyscience Polyscience Polyscience Polyscience Polyscience Polyscience Polyscience Fisher Matheson M C B* Linde Linde Linde Lot # K i. t No. 45c Kit No. 45c Kit No, 17B Kit No. 17B Kit No. 17B Kit No. 17B Kit N o o 17B Kit No. 17B Kit No. 7 IB Kit No. 7 IB Kit No. 7 IB Kit No. 7 IB K it Mo. 32 A Kit No. 32 A Kit N o. 32 A Kit No. 32 A 10 - 5 9 9 L 12-72 D4H0 7 Ultra zero Ultra zero Ultra zero * Matheson , Coleman & Bell. 82 „ MATE RIAL MANUFACTU RE RS Mathcson Coleman & Bell, Manufacturing Chemists, Howoocl, Ohio , 45 212 , U. S , A. Eastman Kodak Co., Ro ches te r, M.Y. , 146 5 0, U.S.A. Mallinckrodt, Incorporated, St. Louis, Missouri, 6 3147, U.S.A. Polyscience Corporation, Niles, IIlinois, 6 0 64 8 , U.S.A. Linde, Union Carbide Canada Ltd., Toronto, Ontario, Canada. Ma theson of Canada Ltd. , Whitbv, Ontario, Canada. Burdick and Jackson Lab. , Muskegon, Michicxan .49442 , U.S.A. Chromatographic Specialties, 300 Laurier Blvd., Brockville, Ontario KGV 5W1, Canada. Alltech Associates, Inc., 2 02 Campus Drive, Arlington heights, 1L 60004, U.S.A. * North American Scientific Chemical Ltd. , 26 8 E, 2nd Avenue, Vancouver, B.C., VST IB7, Canada. ** Fisher Scientific Co. Ltd., 196 W. Third Avenue, Vancouver, B.C. , V 5 Y IE 9, C clll cid 3. ® 83 „ MATE RIAL MANUFACTURERS (Continued) Perkin-EImer Corporation, Main Avenue (Route 7), Norwalk, Connecticut, 06 856 , U.S.A. A** Me dig as Pacific Ltd. , 6 841 Pa1m Avenue, Vancouver B.C. , Canada. * Supplier of MCB, Burdick & Jackson, Mallinckrodt, Eas twan Chemicals. ** Supplier of analytical gases. *** Supplier of helium, hydrogen and air. APPENDIX D. Olfactory thresholds of 34 „ relevan t compounds .* ti ame Fo rmu1a Acetadehyde C2H4Q Acetic acid C2II402 Acrolein C3H40 Ally1 Alcohol C3II60 Allyl disulfide C6H10S2 Ally1 mercapten C3H6S Amnion i a Nil 3 Benzaldehyde C7H60 Benzene thi o1 C6H6S Benzyl Mercapten C71I8S Benzyl sulfide CI 41114S Butane thiol C4H10S -Butanol C4H10 0 Butyl sulfide C8II18S Butyraldehyde C4H80 Butyric acid C4H802 Carbon tetrachloride CC£4 Chloroform CHCil 3 Citral C10H16 0 Coumarin C91I6 02 -Cresol C III 80 Crotyl mercapten C4H8S Decanal C10II2 00 Dimethyl disulfide C2H6S2 Dimethyl amine C2H7N Ethanethiol C2H6S Ether (diethyl) C4H10 0 Ethyl acetate C 411802 Ethyl alcohol C2H60 Ethyl sulfide C4H10S F o rra a ldehyde C 112 0 . Formic acid C 112 02 Ileptanoic acid C7I114Q2 -Ileptanol C7II160 Hexanal C6II120 Hexandic acid C6H1202 Hydrogen sulfide 112S Isobutyl mercapten C4II10S Isobutyraldehyde C4II80 Isobutyric acid C4II8Q2 Isopentyl mercapten C5H12S Isopenty1 sulfide C10II2 2S Isovaleraldehyde C5H100 Isovaleric acid C 5 H10 02 Methane thi o1 CII4S Methyl sulfide C2II63 * Stahl • 1973 ** Exponent base 10 Detection threshold _in_ Air 6.6 0 E-0 2 pom ** 1.00 1.80 E-02 mg/1 1.2 0 E-0 3 ppm 5.0 0 E-05 mg/1 3.70 E-0 2 3.00 E-0 3 6.2 0 E-05 1.90 E-04 6.0 0 E-0 4 1.80 E-02 2.86 E-09 moles/1 1.10 E-0 3 mg/1 2.20 E-0 3 8.0 0 E-01 ppb 4.53 mg/1 3,30 3,00 E-06 3.40 E-04 1.00 E-0 3 ppm * 2. 9 0 E-05 mg/1 1.00 E-03 1.20 E-0 3 ppm * 4.70 E-02 " 6.60 E-07 mg/1 5.83 6.86 E-01 1.00 E+02 2,50 E-04 1.00 ppm 4.50 E+02 mg/1 3.00 mg/1 (water) 5.09 E-01 ppm * 4.00 E-01 3.00 mg/1 (water) 1.30 E-01 ppm 8.00 E-03 mg/1 2.00 E-01 ppb (water) 8.10 ppm (water) 4.30 E-0 4 3.00 E-0 4 mg/1 1.50 E-01 ppb (water) 7.0 0 E-01 ppm (water) 2,00 E-04 mg/1 3.00 E-03 Name Methylamine Octanal Palmitic acid Penty1 sulfide Phenol Phenyl sulfide Propanethiol Propanoic acid 1-Propanol Propionaldehyde Propylsulfide Pyridine Skatole Sulfur dioxide Toluene Tr ime thy1amine Undecanal Valeraldehyde Valeric acid Vanillin p-Xylene Formula ~CH5N " C8K1 C16H32 02 C10H22S C6H60 C12H10S C3H0S C3H602 C 3118 0 C3H60 C 611.14S C5H5N C9H9N S02 Cf7H8 C3II9N C11H220 C5H100 C5II1002 C8H803 C8H1.0 Detection in threshold Air 10 00 00 00 00 80 50 00 00 2.0 10 .40 , 00 70 . 14 , 10 . 00 » 2 0 , 90 . 10 . 70 E-02. E-01 E+01 E-03 E - 0 5 E-05 E+01 E-03 E-Q4 E-04 E-04 E-01 E-04 E-09 E+01 E-02 E-06 E-01 ppm ppb (water) mg./l (water) H ppm mg/1 ti ppm (water) mg/1 ppb ppm ppb tf mg/1 ppb ppm (water) * Recognition 8 6 . LITERATURE CITED ABADIA, D. , J.S. Brinks, E.J. Carroll. 1976. Genetics of seminal traits in young beef bulls. Amer. Soc. of Animal Science, Annual Meeting Pro-ceedings, Vol. 27, p. 30-33, Washington State University. ALLINGER, N. , M. Cava, D. De Jongh, C. Johnson, N, Lebel, and C. Stevens. 1971. Organic Chemistry. Worth Publishers Inc., 444 Park Avenue, South, New York, N.Y. 10016. BARBER, E.M., and J.B. McQuitty. 1974. Hydrogen Sulfide Evolution from Anaerobic Swine Manure. Departmental Report, Department of Agricul-tural Engineering, The University of Alberta. BELL, P.G. 19 70. Fatty acid content as a measure of the odor potential of stored liquid poultry manure. Poultry Science, 49: 1126-1130. BURNETT, W.E, 196 9. Air pollution from animal wastes. Environmental Science and Technology, Vol. 3, Mo. 8, August, p 744-74 9. CARANCI, M., and E. Wrubleski. 1974. Farm, certification as an approach to farm odor problems in Ontario. IN: Proceedings Control Technology for Agricultural Air Pollutants Specialty Conference, p. 117-132. (Air Pollution Control Association, Memphis , T-ennassee) . CHEMICAL RUBBER COMPANY. 1969. Handbook of Chemistry and Physics. 49th Ed. The Chemical Rubber Company , Cleveland, Ohio. DEVLIN, T.J. , J.R. In gal Is, and II. R. Sharma. 1976. High fat oats in ruminant„rations. Am. Soc.^of Animal Science. Annual Meeting Proceedings, Vol. 27, p. 296-299 , Washington State University. DIEBEL, R.H. 1967. Agriculture and the quality of our environment. Am. Assoc, Advance Sci., Pub. No. 85, p. 395-9, Washington, D.C. 37, DRAVNIEKS, A. 19 71. High speed collection of organic vapors from the atmosphere. Environment a]. Science & Technology, p. 1220-1222. HAMMOND, E., P. Kuczala, J. Kozel and G. Junk. 19 Constituents of Swine House Odors. Journal Paper No. J-774 8 of the Iowa Agriculture and Home Economic Experimental Station, Ames, Iowa, p. 36 4 - 372. 11 ARTUNG, L.D., E.G. Hammond and J.R. Miner. 1971. Identification of carbony1 compounds in a swine-buildino atmosphere. IN: Livestock Waste Management and Pollution Abatement, .Am. Soc. of Ag. Engineers, Michigan* p. 105-106. HUEY, N.A,, L.C. Broering, G. A, Jutze and C.W. Gruber. 1960. Objective odor pollution control investigations. J. Air Poll. Control Assoc., 10: 441-446. IFEADI, C.N., E.P. Taiganides and R.K. White. 1975. Quantitative measurement and sensory evaluation of dairy waste odor, p. 35 4-35 7. IN: Managing Live-stock Wastes. Proceedings of the 3rd International Symposium on Livestock Wastes. ASAE Publication PROC-275 . LEHNUNGER, A.L. 19 70. Biochemistry. Worth Publishers Inc. , 70 Fifth Avenue, New York, N.Y, 10011. LUNN, F. and J. Van de Vvver. 19 77. Sampling and analysis of air in pig houses. Agric. Environm., 3:159-169. McGRATH, D. 19 77. Odours arising from the land spreading of pig slurry. Agric, Environm., 3: 171-177. MEIIREN , G.L. 19 66. „ Aesthetics, economics - Animal waste management or rarm animal wastes. Proceedings National Symposium on Animal Waste Management. ASAE Publication No. SP-0366, p.13-19. MERKEL, J.A. , T. E. Ilazen and J.R. Miner. 1969, _ Identification of gases in a confinement swine buildinq atmosphere. Transactions of the ASAE 12: p. 310-315. MERRITT, C. 197 4. A combined GC-MS computer system for the analysis of volatile components of foods. J. Agr. Food Chem. Vol. 22, No.5, p. 750-755. MINER, J., M. Kelly and A. Anderson. 1975. Identification and measurement of volatile compounds within a swine building and measurement of ammonia evolution rates from manure-covered surfaces. Managing Livestock Wastes from Proceedings of the 3rd International Symposium on Livestock Wastes. ASAE Publication Proc-275, p. 351-353. MORRISON, R.T. and R.N. Boyd. 196 7. Organic Chemistry, 2ifd Ed., Allyn and Bacon Inc., Boston. PERRIN, D.D. 196P. Dissociation Constants of Organic Bases in Aqueous Solutions. Pub. London Butterworths, London, U.K. PRICE, D.P. and A.T. Ralson. 1976. Management problems in beef confinement American Society of Animal Science, Annual Meeting Proceedings, Vol. 27, p. 50-51, Washington State University. ROBERTSON, G.R. and T. Jacobs. 1962. Laboratory Practice of Organic Cehmistry. The MacMillan Company, N.Y., N.Y., Collier-MacMixlan Canada Ltd., Toronto, Ontario. ROUSTAN, J.L., A. Aumaitre, Salmon-Legagneur. 1 9 7 7 -Characterization of malodours during anaerobic storage of pig wastes. Agric. Environm., 3: 14/-157, S C H A E F E P S a m p l i i g 7 c h a r a c t e r i Z a t i o n and analysis of malodours. Agric. Environm., 3: 121-127. SCHULTZ, T., R. Flath and R. Mon. 1971. Analysis of orange volatiles w i t h vapor sampling, j. Agr. Food Chem., Vol. 19, No. 6, p. 1060-1065. S ™ L ' " c L ^ t i ^ o f Odor and Taste Threshold Values Data. Mccormick Co., Inc., Baltimore, Met., AoiM Data Series DS48. STANDARD METHODS FOR THE EXAMINATION OF WATER AND WASTEWATER. 197 5. Fourteentli Edition. Published by American Public Health Association, 1015 Eighteenth Street, II.W., Washington, D.C., 20036. STECHER, P., Editor. 1968. The Merck index. Merck and Co., Inc., Rahway, N.J., U.S.A. TAIGANIDES, E.P. and R.L. Stroshine. 1971. Impact of rarm animal production and processing on the total environment. Livestock Management and Pollution Abatement Proceedings, International Symposium on Livestock Wastes. ASAE Publication PROC-2 71, p. 9 5-9 8. TIMMER, R. , R. Heide, P. rieValoid, and II. Wobben. 19 71. Qua.lita.tive analysis of the most volatile neutral components of reunion geranium oil. J. Agr„ Food Chem. Vol. 19, No. 6, p. 106 6-1068. TRAVIS, F.A., and L. Elliott. 1977. Quantitation of indole and skatole in a housed swine unit. J. Environ. Qual. , 'vol. 6, No. 4, p. 407-410. WHITE, R.K., E.P. Taiganidesf and G.D. Cole. 1971. Chromatographic identification of malodors from dairy animal v.aste. Livestock Waste Management and Pollution Abatement. Am. Soc. of Ag, Engineers, Michigan., p. 110-113. WILLRICH, T.L., and J.R. Miner. 1971. Litigation experiences of five livestock and poultry producers. Livestock Waste Management and Pollution Abatement. Proceedings Internation Symposium on Livestock Wastes. ASAE Pub. PROC-2 71, p. 99-101. ZAIED, A. A. , W.D. Humphrey, T.D. Dunn, and. C.C. Kaltenbaciu 1976. Extrous synchronisation with ovulation control or timed insemination. Am. Soc. of Animal Science, Annual Meetincr Proceedings, Washington State University, Vol. 27, p. 199-200. ZILSTORFF- PEDERSON, K. 1.96 4, , Determination and variation of Olfactory tftresnoxds. Arch. Otolaryngol. Vol. 79, p. 412-417. 

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