An effect of magnetic field exposure on microorganisms associated with fuel oil

Two 30 urn tortuous path depth filters, associated with either a magnetic or non‐magnetic, but otherwise identical, fuel treatment device were placed in a tandem recirculating fuel oil system comprising a single reservoir of fuel oil (red diesel) contaminated with seawater and fuel degrading microbes. For 17 d the recirculating system, with no added mixing of the reservoir, showed no significant decrease in performance (measured through volume flux). On perturbation and constant gentle mixing of the reservoir thereafter, the volume flux after the filter associated with the magnetic device decreased linearly over the next 18 d to ca 65% of its initial stable value. The volume flux after the filter with the non‐magnetic device decreased much more quickly to around 25% of its initial stable value. The rate of reduction in volume flux after the non‐magnetic device appeared to increase with time. Both filters were being blocked but the one associated with the magnetic device did so at a significantly slower rate. Differences in the size‐frequency distributions of particles (> 12 μm) mea‐sured in samples taken from upstream and downstream of the devices throughout the study pointed tentatively to hydrodynamic effects when large particles were abundant. No significant difference in the abundance of culturable microbes in seawater collected from the water separator bowls of the filter units associated with each device was found, both having comparable levels to the bottom (sea) water of the reservoir tank. No evidence for microbial growth limitation in the reservoir tank was found, abundance being comparable to that obtained from carefully grown laboratory cultures of the same microbes. Filter fouling was determined to be largely biogenic, consisting of microbes and their extracellular products with a visible difference in the structure of the fouling of each filter using SEM.

Key words:

• biomagnetics
• magnetism
• magnetic fuel treatment
• bacteria
• microbes

Notes

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