Bioremediation of Oil-Contaminated Fine Sediments

Abstract

Bioremediation of oil contamination has been shown to be effective for cobble and sandy shorelines. To assess the operational limitations of this technology, this project studied its potential to treat buried oil in fine sediments. The effectiveness of bioremediation by nutrient enrichment with water-soluble mineral fertilizers was quantified experimentally with a randomised block design with three replicate blocks. Each block consisted of an untreated control plot, a plot treated with fertilizer alone, an oiled plot, and an oiled plot treated with fertilizer. The sediment in each plot was retained in mesh enclosures and buried at a depth of 0.15 m. Weathered and emulsified Arabian Light crude oil was applied to the appropriate plots at 3.7 kg.m−−2. Bioremediation success was monitored by examining in situ CO2 production rates; changes in residual hydrocarbons normalized to 17?(H), 21?H)-hopane; and response of hydrocarbon-degrading microorganisms. Fertilizer treatments significantly increased the biodegradation of petroleum hydrocarbons (p = 0.0001) in the buried sediments. These conclusions were supported by in situ CO2 production data. Microbiological analyses showed that nutrient addition increased the numbers of hydrocarbon-degraders on the oiled plots tenfold. The results clearly showed that bioremediation can treat oil buried in fine sediment following a spill incident.

Evaluation of Bioremediation Treatments in a Shoreline-Simulating Microcosm

“…The most intense phase of biodegradation is usually coupled with increased biological activity (Marge sin and Scinner, 1997). Swannell et al (1995) reported a notable increase in the numbers of heterotrophs as a result of continuous addition of nutrients, compared with unfertilized oil-contaminated control in shore line simulating conditions. In cold alpine environment, significant decontamination of diesel oil contaminated soil was observed by Margesin and Schinner (2001).…”

“…Therefore, other types of microbial methods have been applied to monitor the microbial activity in the contaminated soil. The re-150 sidual hydrocarbon concentration has been observed to correlate well with different microbial parameters such as microbial counts, respiration, and enzyme activities (Margesin and Schirmer, 2001;Swannell et al, 1995;Ramstadt et aI., 1995). In this study the ATP content, SIR, and number of heterotrophic bacteria in sand column were determined.…”

“…In our microcosm, oil is applied on the top of a 20-cm-thick sand column, which represents the behavior of oil on the beach after a spill. Swannell et al (1995) delicately combined CO 2 analysis as a measure of microbial activity, with the sediment column test simulating the dynamic conditions on tidal beach. However, as in the most of the test systems simulating oil biodegradation in beach ecosystems (Croft et al, 1995;Lin et al, 1999;Swannell et al, 1995;Whiteside and Bhattacharya, 1997), residual oil analyses were required to determine the extent of biodegradation.…”

A performance assessment of source correlation and weathering indices for petroleum hydrocarbons in the environment

“…Pande et al [11] used the second of these indices to monitor biodegradation of crude oils, obtaining a spread of values from 200 for the freshest oil to 4.3 for the most degraded. Swannell et al [23] used variation in the latter two indices to monitor the biodegradation of an Arabian crude oil. Significant shifts were recorded in the value of the ratio of total alkyl polycyclic aromatic hydrocarbons to 17α( H ), 21 β( H )‐hopane, which decreased from 43 in the freshest oil to undetected in the most degraded samples.…”

Bioremediation of marine oil spills

“…Since then, bioremediation has been used on a limited site as part up of the cleanup of the Sea Empress spill [42], and has been demonstrated on experimental spills in marine or brackish environments on the Delaware Bay [43], a Texas wetland [44], a fine-sand beach in England [45], mangroves in Australia [46], and an Arctic shoreline in Spitsbergen [47]. It is likely to be included in responses to future spills where oil strands on rocky or inaccessible shorelines.…”