Microbial Contamination of Ship Fuels

Abstract

A laboratory evaluation has been made of water-soluble biocides which might be effective in controlling microbial contamination in water-compensated fuel storage tanks on naval ships. Higher concentrations of biocides were generally required for control of sulfate-reducing bacteria in steel drums simulating ships' tanks than in test-tube scale assays. At least tenfold higher concentrations were necessary when biocide additions were made after, rather than before, bacterial growth had developed extensively. A mercaptopyridine biocide was effective at the lowest concentration followed by methylene bisthiocyanate and a triazine derivative; an organoboron compound was comparatively ineffective. Attention has also been given to the possible environmental impact of discharging biocide-treated water. An algal assay has been used to study the loss in toxicity of candidate biocides in seawater solution on exposure to sunlight. The mercaptopyridine biocide was particularly susceptible to photodegradation. Thus it may be possible to control microbial contamination indefinitely in a dark fuel tank with a biocide which photodegrades to nontoxic products when discharged into sunlit surface waters.

Microbiological problems in the offshore oil and gas industries

“…Tanks in the platform jacket can also contain ballast water or be used for the storage of potable water and fuel oils (Crouch 1982). Neihof & May (1982) have reported that SRB predominated in water, sludge and diesel oil samples from over 40 fuel storage tanks using a seawater-compensated ballasting system. (2) Seawater is used for the hydrostatic testing of pipelines and can remain within the pipeline for several months.…”

Alkane utilisation by Cladosporium resinae: the importance of extended lag phases when assessing substrate optima

“…cedures, C. resinae has now been shown to cause similar problems within the fuel systems of ships powered by gas turbines [5]. Growth of C. resinae and other micro-organisms occurs predominantly at the hydrocarbon-water interface in tanks where the fuel is displaced by seawater.…”

Factors affecting population development within seawater-displaced fuel tanks

“…2). The delay in the initiation of growth by filamentous fungi until the pH of the aqueous phase was considerably more acidic than at the time of inoculation may suggest a role for yeasts as acidifying agents [4]. However, such a delay was also observed in pure cultures of the filamentous species in which aqueous phase pH did not alter before growth.…”

“…Filamentous fungi, in particular Ciadosporiurn resinae, have been implicated as the major organisms blocking fuel filters [2,3] but the development of other contaminating populations has been largely neglected. The action of Candida yeasts as primary contaminating agents has been suggested as essential before filamentous fungi can exploit the environment [4]. Such acid-producing alkali-tolerant yeasts are thought to change the value of the pH of the aqueous phase, allowing filamentous organisms to initiate growth.…”