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Optimal conditions for decomposition of oily sludge

Belcher, Teresa A (1992) Optimal conditions for decomposition of oily sludge. Honours thesis, Murdoch University.

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The optimal conditions for decomposition of oily sludge were investigated at BP Refinery (Kwinana), by of a set of field trials together with laboratory experiments. Field trials tested the effect of oily sludge load,
frequency of tilling and the addition of fertiliser on the rate of degradation of oily sludge. Laboratory trials investigated, under controlled conditions, the effects of oily sludge load, moisture, temperature, aeration and the addition of manure. Investigations of the bacterial population included monitoring the change in bacteria numbers, diversity and C02 production after oily sludge application.

There was significant degradation of oil in all field trial plots over 6 months. From three loadings of oil (3%, 6% and 12%), 12% oil showed the greatest overall percentage reduction. Testing three frequencies of tilling, to provide aeration to the soil, found weekly tilling to be optimal for oil breakdown. The effects of inorganic fertiliser and manure were not statistically significant but the results suggest that degradation was enhanced by their addition. Addition of manure may provide both the nutritional requirement for degradation and enhance co-metabolism as well as the bulky matter providing air spaces and allow for extra retention of moisture. Of the combinations tested, 12% oily sludge loading, weekly tilling and the addition of fertiliser or manure were optimal.

Hydrocarbon traces over time revealed the preferential disappearance of the n-alkanes.

Contamination of hydrocarbons was not found to occur below the zone of incorporation beneath the field trial plots.

The monitoring of the bacterial populations revealed a change in diversity of species after oil application. Application of oily sludge stimulated the growth of hydrocarbon degrading bacteria. Greater numbers were found in 12% oil plots as compared to 6% and control plots. Species that were isolated and identified as hydrocarbon degraders included bacteria of the genera Pseudomonas, Agro bacterium, Aeromonas and the families Micrococcus and Bacillus.

The process of landfarming, with careful maintenance and monitoring, was found to be a cheap and adequate method of disposal of oily sludge.

Item Type: Thesis (Honours)
Murdoch Affiliation(s): School of Biological and Environmental Sciences
United Nations SDGs: Goal 12: Responsible Consumption and Production
Notes: A digital copy of this thesis is not available. Your library can request a copy from Murdoch University Library via Document Delivery. A fee applies to this service.
Supervisor(s): Ho, Goen and Lukatelich, Rod
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