Anaerobic bioremediation of marine sediment artificially contaminated with anthracene and naphthalene.

The bioremediation of marine sediments contaminated with naphthalene and anthracene was studied under anaerobic conditions to investigate the enhancing effect of a biostimulating agent (Tween 80, silicone oil, pig dung and NPK fertilizer) on the rate of degradation. Sediment samples were amended with the biostimulating agent (alone or in combination). The results showed that all the tested agents, applied individually to the sediments, increased the rate of anthracene and naphthalene degradation, with the pig dung having the greatest effect. The biodegradation data were fitted to a pseudo-first-order kinetic model, from which the biodegradation rate constant, as a measure of the enhancement of degradation rate by the biostimulators, was estimated. The rate constant values were consistently higher for the sediments treated with individual stimulators, or a combination of them, than for the untreated sediment. The contaminated sediment treated with the combination of Tween 80 and pig dung exhibited the highest biodegradation rate. The results indicated that the effect of various biostimulating agents, in combination or alone, on enhancing the degradation rate of anthracene and naphthalene can be arranged in the following order: Tween 80 + pig dung > silicone oil + pig dung > Tween 80 + NPK fertilizer > silicone oil + NPK fertilizer > pig dung > NPK fertilizer > Tween 80 > silicone oil. The addition of biostimulators increased the biodegradation potential of the intrinsic microbial populations; thus, these results will contribute to the development of new strategies for in situ bioremediation of anoxic sediments contaminated with polycyclic aromatic hydrocarbons