A race track type oxidation ditch with a disc aerator was constructed on a model scale. Tests were conducted in deionized water to study the effect of some disc design parameters and system operating parameters on the oxygen transfer rate was affected by the disc speed, disc thickness, hole diameter, immersion depth and number of discs operated in parallel. / The effect of the manure concentration on the microbial growth was investigated in a batch culture operation. High manure concentration had an inhibitory effect on the microbial growth. / Data from batch culture operation were used to design a continuous culture operation. The latter was used to evaluate the concept of minimal aeration of swine manure for odor control. The effluent quality (as measured by odor level and the concentrations of COD, nitrogenous componds and solids) was dependent on the initial manure concentration and on the retention time. The effluent from the ditch was free of offensive odor and can be spread on land without causing odor pollution problem.

Liquid hog manure (LHM) obtained from the Macdonald College farm was used in experiments aimed at (a) reducing the odor associated with LHM during handling and (b) conserving the fertilizer capacity of LHM. Various chemical treatments and sphagnum moss (SM) were evaluated to achieve the above objectives. Direct acidification to $<$ pH 5.0, sphagnum moss (SM) and its combination with aluminum sulfate (AS) resulted in significant (p $<$ 0.05) reduction in ammonia losses during storage of LHM. The SM and SM/AS combination also significantly (p $<$ 0.05) reduced both odor presence and offensiveness. Gas chromatographic (GC) and GC/mass spectrometry (GC/MS) analysis indicated the absence of certain malodor compounds and lower peak areas of certain compounds in the SM and SM/AS treatments when compared to the controls. Investigations with barley seeding revealed that treatments which reduced the malodor of the LHM did not significantly (p $<$ 0.05) affect the nitrogen fertilization capacity of the LHM, as indicated by plant dry matter yield.

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No description available.

The research objective was to calibrate a model to simulate odour dispersion downwind from natural windbreaks and then, use this model to observe the effect of windbreak characteristics and climatic conditions on the size of the odour dispersion plume. Computational fluid dynamic (CFD) models were used for the simulations because of their capability in reproducing turbulent wind conditions. The model was initially calibrated to ensure the proper velocity recovery ratio (VRR), and then to reproduce odour plumes measured in the field by three groups of four panellists. / The visual and statistical analysis of the field panellist observations indicated that a windbreak with an optical porosity of 0.35 could reduce by 21% the length of the odour dispersion plume, as compared to a site without a windbreak. Also, these analyses indicated that the site with a windbreak offering an optical porosity of 0.55 had no significant impact on the length of the odour plume, as compared to the site without a windbreak. / The models selected for the simulations were the Fluent 6.2 standard k-epsilon and SST k-o models. Their odour dispersion calibration indicated that both models can accurately reproduce the field measured odour hedonic tone and odour concentration by transforming the odour mass fraction computed by the models into the hedonic tone with a power function, and then into the odour concentration with an exponential function. The correlations between the simulated and measured absolute HT and between the simulated and measured odour concentrations were statistically significant (P < 0.01). However, the SST k-o was preferred over the standard k-epsilon because it could physically better reproduce the high turbulence conditions created by the windbreak. / The SST k-o model simulations indicated that odour plume length was mostly affected by windbreak porosity and height, as well as distance from the source. In terms of climatic conditions, odour plume size was mostly affected for atmospheric stability conditions which generally established ambient wind speed and rate of change of temperature. Wind direction has an impact on the length of the odour plume and the formation of a fin intensifying odour concentration near the windbreak, where an angle of 45º produces the shortest odour plume and the largest fin. / Key words: Simulation; odour; dispersion; natural Windbreak; CFD.

No description available.