Toxicity evaluation of a commercial bioremediation agent mixed with crude oil

Abstract

The toxicity and efficacy of a bacteria-based commercial bioremediation agent (CBA) was assessed through bioassays with juvenile inland silverside minnows, Menidia beryllina, and flask studies of oil degradation. Addition of the CBA to weathered Alaska, USA North Slope crude oil (ANS-521) prior to testing increased toxicity of the water-soluble fraction (WSF) of the oil in both chronic (growth) and acute (mortality) toxicity tests. Time-course toxicity assessment of the water-soluble fraction of the CBA/oil combination indicated increases in effect after 7 to 14 d of mixing that coincided with elevated concentrations of both alkanes and aromatics in the WSF. Under controlled laboratory conditions, the CBA significantly enhanced degradation of the oil compared with a treatment with nutrients alone. The alkane fraction was degraded by nearly 100% over a 42-d period while the aromatic fraction was decreased by 70%. While toxicity testing is not currently required to list bioremediation agents on the product schedule of the National Oil and Hazardous Substances Pollution Contingency Plan, the potential interaction between bioremediation agents and oil should be further investigated and listing requirements reassessed as necessary. Recommendations for future investigations of this issue include characterization of temporal trends in toxicity of CBA and oil mixtures, use of multiple test methods (battery testing) when evaluating toxicity, comparative evaluations of indigenous versus product-derived microorganisms in efficacy studies, and the use of a comparable oil between studies to facilitate comparison of efficacy and toxicity data for different products.

Cow Dung as a Bioremediation Agent to Petroleum Hydrocarbon Contaminated Agricultural Soils

“…These methods are however expensive when contaminated areas are large [4] and it may pose possible collateral destruction of the site material or its indigenous flora and fauna [10,11]. Bioremediation processes that employ the use of microorganisms to degrade environmental contaminants [12,13,14], have also proved effective and could be used to accomplish both effective detoxification and volume reduction. Bioremediation is mainly based on the ability of microorganisms to destroy or degrade organic compounds or minimize the concentration of these materials by the detoxification or mineralization of the organic pollutants to carbon dioxide and water.…”

“…The advantage of this remediation process over physicochemical remediation method is that it is believed to be non-invasive and relatively cost-effective [16]. Bioremediation processes could be enhanced either by addition of commercial microbe cultures (bio-augmentation) [17,18,19] or by nutrient enrichment (bio-stimulation) of the natural microbial population [13,14]. Numerous laboratory studies on the use of fertilizer to enhance oil biodegradation by naturally occurring microbes have concluded that fertilizer use has the potential as a treatment technique for removing hydrocarbon in an impacted area [20].…”