Abstract
This thesis deals with the investigation by various chemical means, of the deodorant action of ammonium persulphate on bovine faecal slurry. A reliable method was developed whereby volatile constituents of the slurry could be detected gas chromato-graphically using a technique of precolumn trapping. Steam distillation and various reduced pressure distillation methods were also employed to provide samples for gas chromatography. Tentative identifications were made from retention data and this information was reinforced by combined gas chromatography and mass spectroscopy. This allowed confirmation of many tentative identifications and the detection of several further compounds. Confident identifications included methane, carbon dioxide, hydrogen sulphide, ammonia, n-propane, methane-thiol, ethanol, methanol, ethanol, acetone, dimethyl sulphide, 2-propanol, 2-butanone, furfural, 2-methylpropanal, 3-methylbutanal, benzene, toluene, ethylbenzene, chloroform, carbon tetrachloride, indole and 3-methylindole. Derivative preparation (2;4 DNPH) followed by thin-layer chromatography was used to study the carbonyl compounds and an organoleptic assessment of g.c. eluates confirmed the identification of several other compounds. The halocarbons were studied by electron-capture gas chromatography. Comparison of treated and untreated slurries showed the chief odour compounds to be hydrogen sulphide and dimethyl sulphide. Attempts to duplicate persulphate action showed its main influence to be due to pH reduction. It was found that this caused a redistribution of the slurry flora toward a non odour-producing fungal population. Its oxidising power and its ability to release free oxygen were also shown to play a part. A novel method was developed to determine the concentration of persulphate in treated slurry. This demonstrated the short lifetime of this compound in slurry and supported the hypothesis of indirect action.