Removal of heavy oil using rhinoceros beetle, Oryctes rhinoceros

The remnant of heavy oil, often expressed as total petroleum hydrocarbons (TPHs), in soil and/or sludge is commonly encountered by and often ruins the habitat of some indigenous insects. Recent studies indicate that some of the insects could stand the impact and some not just survived but might serve as an oil degrader. The potential of using indigenous insects in treating oil pollution is of interests in this study. In Asia, the potential oil-exposed rhinoceros beetle, Oryctes rhinoceros, was studied herein due to two major interests: one is its tolerance to heavy oil, and the other its ability to remove the oil. Two sets of the experiments spiked with different amounts of heavy oil were conducted in series, and the results of the larval mortality rate, growth rate, feces production, substrate conversion ratio and percent of oil removal were monitored as performance indicators during these treatments. The obtained results showed that the ingestion of heavy oil at a 5000 mg/kg level significantly deteriorated the survival rate (37% left) of the tested larvae, yet oil-experienced larvae could survive in up to 10,000 mg/kg of heavy oil (100% survived). As for the heavy oil removal via larval ingestion, at a 10,000 mg/kg level of oil in the substrate, the percent of weekly removal of heavy oil by larva ingestion was consistent throughout the second run at 56.4 ± 5.6%. These results demonstrated the potential use of beetle larvae as a bioreactor in pollutant removal.