Publisher: Bachudo Science Co. Ltd

A Laboratory Assessment of Anaerobic Biodegradation of Petroleum Hydrocarbons In A Typical Niger Delta Wetland

G. 0. Abu, O. N. Akomah, G. O. Abu
KEYWORDS: Anaerobic biodegradation, Sulphate reducing bacteria, petroleum hyc'rocarbons, terminal electron acceptors, laboratory investigation

ABSTRACT:

Anaerobic degradation of hydrocarbons in sediment samples from a wetl3nd environment that had been impacted by crude oil for more than thirty years was investigated in the laboratory. The experiment comprised sterile and non-sterile treatments of the sediment samples that were incubated either aerobically or anaerobically in flasks designated A, B, C, D and E. Some treatments were amended with inorganic fertilizer. The experiment was monitored by the measurement of heterotrophic bacterial activities, hydrocarbon utilizing bacterial activities, sulphate reducing bacterial activities. gravimetric loss of oil with time. The pH, Dissolved Oxygen (DO), conductivity, nitrate, sulphate and phosphate of the treatment conditions were monitored. The Dissolved Oxygen (DO) of various options tended towards zero while flask B recorded a net (DO) value of 0.3 mglf. The pH of most treatment options was moderate with flask C giving the highest value of 8.50. There was total hydrocarbon loss of 18 %, 60 %, 57 %, 49.5 % 43 7 %, for the test conditions A, B, C, D and E respectively. Counts of aerobic heterotrophic bacteria rahged between 1.8 x 10 5 and 2 5 x 105 cfu/g. Counts of anaerobic heterotrophic bacteria ranged between 8.5 x 104 and 9.5 x 104 cfulg. Counts of sulphate reducing bacteria ranged between 3.4 x 104 - 1.6 x 105 cells/ml. The levels of nitrate, phosphate and sulphate decreased with time during the study period except in flask A The results indicate that there is a significant difference (P<0.05) between total hydrocarbon level and number of days of incubation. Biostimulating the sediment under anaerobic conditions has almost the same effect on hydrocarbon degradation as under aerobic conditions It is recommended that these conditions be optimized under field situation to enhance anaerobic bioremediation of anoxic environments in the Niger Delta.


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