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Odour production and oxygen consumption under controlled composting conditions

University of British Columbia

Odour emissions from compost facilities can be a public nuisance that causes problems for the operators in the business. Reducing odours, by controlling the compost process, is not clearly understood, and this was the focus of this project. If the production rate is compromised by these modifications, then it would be useful to know a quantitative estimate of the effect. Experiments were run to evaluate the independent influence of oxygen concentration, temperature and enrichment inoculation on odour concentration and emission rate produced by compost. The air flow rate and the oxygen concentration provide an estimate of the production rate as calculated from the oxygen uptake rate. The experiment was a complete 3X2 factorial, with a face-centre point for the non-enrichment inoculation. The results show that there was a significant effect due to inoculation and temperature, on the odour emission rate and on the air flow rate, but not on the odour concentration. The oxygen concentration factor was consistently the most influential treatment on the odour concentration, the air flow rate, and the odour emission rate, however the confidence level for the odour concentration was always low, due to the high variability of human olfactories. The oxygen uptake rate remained constant from 6% to 16% oxygen, and decreased by about 10% from 55°C to 69°C. This change was small when compared to the decrease in odour emission rate of 50%, over the same temperature range. Odour concentrations varied from 1700 to 10,000 dilutions to threshold, for a mixture of vegetable wastes and poultry manure. The enrichment inoculation caused odour concentrations to increase, which is the opposite of what was expected. The results of the experiment are used to suggest improvement methods to commercial scale composting, with the understanding that there is limited accuracy.

Thesis/Dissertation

application/pdf

2009-05-04

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http://hdl.handle.net/2429/7826

Chemical and Biological Engineering

University of British Columbia

UBCV

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