Enhanced degradation of a model oil compound in soil using a liquid foam-microbe formulation

This paper describes the development of a protein-based foam formulation an d subsequent investigations into its suitability to enhance the degradation of a model hydrocarbon (n-hexadecane) using novel bench-scale soil microco sms. High-density protein-based foam concentrates based upon those develope d by the fire-fighting industry were selected for experimental investigatio n. Using crude protein hydrolysate as a starting material, a foam formulati on was developed with properties suitable for bioremediation studies. This formulation incorporated eight hydrocarbon-degrading bacteria that had been selected for their ability to degrade hexadecane. In addition to their abi lity to utilize n-hexadecane, the bacteria were tested for compatibility wi th the foam formulation and each other. Seven individual Acinetobacter spp. and a Pseudomonas species were selected for use in the consortium based on these criteria. The use of this "bioactive foam" led to enhanced n-hexadec ane degradation when compared to controls without foam. Following 7-d incub ation, 60% of the n-hexadecane remained in the soil column using a foamed f ormulation, as compared to 90% with a nonfoamed control. In a subsequent ex periment over a 15-d time course, the authors observed significantly greate r n-hexadecane degradation in response to oxygenated bioactive foam treatme nt.