Enhancement of recovery of residual oil using a biosurfactant slug

A laboratory investigation of the mobilization and displacement of residual oil in a sand-pack using biosurfactant slug was conducted. The biosurfactant employed was extracted from a culture of Pseudomonas sp. grown on kerosine- supplemented mineral salts medium. Characterization of the biosurfactant extract revealed a mixture of glycolipid and phospholipid in a ratio of 3.35:1. The irreducible water saturation (Swi) and initial residual oil saturation (Sor) of the sand-pack were 0.280 ± 0.003 and 0.373 ± 0.006, respectively. Core flooding experiment showed that an optimum oil recovery of 52.19% of the in-place residual oil was achieved at biosurfactant incubation time (BIT) of 120 h. These results suggest that biosurfactant produced by Pseudomonas species is a potential “candidate” for microbially enhanced oil recovery.Keywords: Laboratory investigation, enhanced oil recovery, biosurfactant slug, Pseudomonas specie

COMPARATIVE TOXICITIES OF THREE AGRO-INSECTICIDE FORMULATIONS ON NITRIFYING BACTERIA

ABSTRACT: The toxicity of three agro-insecticides -Lindane, Diazinon and Carbofuran formulations-on Nitrobacter and Nitrosomonas sp. were investigated. Changes in populations and activities of bacteria isolated from soil samples in the Niger Delta area were monitored following their exposure to different concentrations of the agroinsecticides for four hours. Results of toxicity studies revealed that the median lethal (LC 5

Biodegradation of Polyethylene by Bacillus sp. Indigenous to the Niger Delta Mangrove Swamp

The ability of Bacillus mycoides and Bacillus subtilis (Bacillus species indigenous to the Niger Delta mangrove soil) to biodegrade polyethylene was studied. Low-density polyethylene (LDPE) and high-density polyethylene (HDPE) films were exposed outdoor for 24 weeks. The two isolates were able to grow on polyethylene (PE), forming visible biofilms. The plasmid pattern of the Bacillus species showed a similar pattern among the two Bacillus species, with one plasmid number and molecular weight around 25 kb, indicating a mega plasmid. The mean heterotrophic bacterial counts in the mangrove soil ranged between 2.81 x 105 – 3.20 x 108 CFU/g. The rate of degradation was determined by measurement of the residual weight of the PE films. Biodegradation in Erlenmeyer flasks by the bacteria after 60 days of incubation ranged between 8.41%-23.15%. Biodegradation was confirmed by Fourier-Transform Infrared (FTIR) spectroscopy, which showed introduction of carbonyl groups after natural weathering, which decreased after microbial treatment. Decrease in carbonyl index ranged between 10.5%-13.7%. The result showed that certain Bacillus sp. indigenous to the Niger Delta mangrove soil are capable of growing on PE films and biodegrade them, after an initial abiotic degradation.Key words: Bacillus mycoides, Bacillus subtilis, biodegradation, carbonyl index, Natural weathering, Niger Delta mangrove