Major Results of Research and Development in Fiscal 2004 II-5

5. A compound to suppress the emergence of the iron bacterium sludge that disturbs tunnel drainage

Development of a compound to suppress the emergence of the iron bacterium sludge that disturbs tunnel drainage

A gelatinous brown sludge is often generated by ferrous bacteria at leakage points in tunnels, which can clog troughs and drainage ditches (Fig. 1), and saline water that has pooled due to insufficient drainage causes corrosion to the reinforcing bars in concrete structures. To properly maintain tunnels, therefore, it is necessary to regularly remove the ferrous bacterium sludge, incurring enormous maintenance costs.
The RTRI developed a soapy compound (costing about 1,000 yen per 200g) that gradually oozes an antimicrobial substance when placed in spring water. A performance confirmation test of the compound in a tunnel showed that the generation of ferrous bacterium sludge was suppressed for three months when the leakage was up to 1,300L/min (Fig. 2), suggesting that the cleaning periodicity would significantly be extended.

Fig.1 Ferrous bacterium sludge

	Fig. 2 Results of antimicrobial performance confirmation test (after three months)

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