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C. Experiments in a High-temperature Aerobic Fermentation Apparatus (middle)
1）Experimental Methods
The experiment was executed using the high-temperature aerobic fermentation apparatus (middle) satisfying the conditions mentioned "B. 1)". The apparatus was Eco-up T-25S (Fig. 7), in which 8 sheets of SBS (15cmx15cm) including bunker C (0.6kg) and the bark compost were placed (Fig. 8). The oil content at the beginning of this experiment was 50000 ppm in whole of the tank. The bark compost and bunker C were the same as the experiment of "B. 1)”.
There were 3 stirring bars, one of the bars has the hole for the air flowing for ventilation, which activate the fermentation. The stirring rate was set at 1 rotation per minute. The experiment was executed Nov.11, 2002 to Jan. 6, 2003.
2）Results
The oil content during the experimental term is showed at Fig. 9. This experiment is in near concept expected as the real SBS disposal, for the target of decomposition is very SBS with bunker C. It means that the oil content in the tank would not be uniform while the shapes of SBS remain. (The theoretical oil content was 50000 ppm.) In this context, the basis of the discussion would be 10000 ppm, oil content after 1 week, and after 2-8 weeks, it was reduced to less than 5000 ppm. The microbial counts in the tank had been kept at high level through the experimental term (Fig. 10).
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Fig. 7
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High-temperature aerobic fermentation apparatus (middle) (Eco-up T-25S)
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Fig. 8
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Compost and SBS
with oil in the tank
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Fig. 9 Changes in the oil content
Fig. 10 Changes in the microbial counts
III. CONCLUSION
The following points were clarified in the present study.
（1）After one to several months, oil was not perceptible from the sample of SBS and absorbed bunker C.
（2）In experiments in a high-temperature aerobic fermentation apparatus (middle), the oil content of bark compost and bunker C was reduced from 10000 ppm to 2000-5000 ppm after 1 to several week-period.
Additionally, using the compost made from SBS with bunker C, there was not any problem to grow the grasses for a month. To use the compost as fertilizer, we must execute further experiment carefully and confirm its safety in detail.
On the other hand, in experiments in a high-temperature aerobic fermentation apparatus (small), we have not got the significant and stable results of this technology yet. We must discuss and research with the experts of this field including the experimental method.
Although there are still several questions, this technology is expected to be the technology with low environmental load appealing the biodegradability, which is the specification of SBS.
ACKNOWLEDGEMENT
We are deeply grateful for the support by the Nippon Foundation, for the advice by Prof. Hajime Yamaguchi, Tokyo Univ., Prof. Ryuichiro Kondo, Kyushu Univ. and Dr. Takeshi Naganuma, Hiroshima Univ., and for the material supply by Kyushu-Sekiyu Inc.
REFERENCES
[1] M. Saito, et al., "Development of SBS for Marine Oil Spill Response (1st Report)," Journal of the Society of Naval Architects of Japan, No.190, 2001, pp.287-294.
[2] M. Saito, et al.: "Development and Water Tank Tests of SBS," Papers of IMO 3rd R&D Forum on High-density Oil Spill Response, 2002, Session III ID39 pp.1-9.
[3] Joergensen, R.G. et al., "Microbial Decomposition of Fuel Oil after Compost Addition to Soil," Z. Pflanzenernahr. Bodenk., No.160, 1997, pp.21-24.
[4] Joegensen, K.S. et al., "Bioremediation of Petroleum Hydrocarbon-contaminated Soil by Composting in Biopiles", Elsevier Environmental Pollution, No.107, 2000, pp.245-254.
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