Bacterial Treatment of Drill Cuttings: Experimental Investigation

During exploration and development drilling operations, the presence of polycyclic aromatic hydrocarbons (PAH) from crude oil and gas condensate, ferrochrome lignosulphate, and lead compounds in drill cuttings and drilling mud additives is a source of concern for the environment. This investigation was prompted by the environmental toxicants discovered during drilling operations. This study was focused on using scientific and technological methods that are both efficient and cost-effective in lowering chemical toxicants in the environment to levels below the permissible limit, in order to fulfill the millennium objective of a sustainable environment. This goal was achieved by inducing PAH and TPH breakdown in the hydrocarbon using microorganisms found in drill cuttings. The physiochemical factors that promote the proliferation of hydrocarbon-using bacteria have been identified. Throughout the investigation, microbial populations, total petroleum hydrocarbon (TPH), and PAH levels were measured at regular intervals. Drill cutting (Dc) from an oil well in the Usan field was sampled for bioremediation treatment. Using plastic bowls, the five treatment choices Dc, Dc+S, Dc+F, Dc+S+F+D, and Dc+D were established in triplicates in distinct cells. A total of 15 plastic bowls with a diameter of 35cm and a depth of 11cm were used. Throughout the study period, the setup was sampled at regular intervals for analysis. Four treatment alternatives were biostimulated with soil (S), NPK fertiliser (F), or Gold Crew dispersant (D), with controls (DC) and heat-treated (hDC).For each treatment choice, 40g of treatment material was added to 2 kg (wet weight) of drill cutting. A 56-day study period was used to investigate the bioremediation process. On day 0, the unaffected treatment (Dc) had the greatest heterotrophic bacterial count (4.5 x 105 cfu/g), whereas Dc+D had the lowest (3.0 x 103 cfu/g) on day 56.

Dc+D had the highest count (6.5x 103 cfu/g) on day 28 and the lowest level (2.6 x 102 cfu/g) on day 56, according to the hydrocarbon utilizing bacterial count. On day 0, total petroleum hydrocarbons (TPH) ranged from 33.22 to 46.00 mg/kg for all treatment choices, whereas polycyclic aromatic hydrocarbons (PAH) ranged from 3.51 to 6.4 mg/kg. In all the treatment option by day 56, the TPH was <8.0mg/kg and PAH <2.5mg/kg. By day 56, the percentages of biodegradation of TPH as measured with GC-FID were Dc(71.82%), Dc+S(77.09%), Dc+F(83.58%), Dc+S+F+D(79.95%), Dc+D(81.58%) and heat-treated (30.56%). PAH percentage degradation rates were as follows: Dc (49.92%), Dc+S (52.35%), Dc+F (86.09%), Dc+S+F+D (64.74%), Dc+D (74.20%) and heat-treated (2.23%). Dc+F gave the highest percentage degradation for both TPH and PAH. Fifty-two hydrocarbons were produced using bacterial isolates. Bacillus spp. (26.92%), Proteus Sp. (1.92%), Pseudomonas spp. (7.36%), Alcaligenes spp. (5.77%), Micrococcus spp. (7.55%), Acinetobacter sp. (1.92%), Aeromonas spp. (21.15%), and unidentified bacteria were among the bacteria isolated (28.85 percent ).Many of the bacterial isolates displayed hydrocarbon degradative capability, according to a screen test for degradative potential. As indicated in the heat-treated control, the drill cuttings analysed could be remediated utilising microbiological agents, and environmental conditions (abiotic factors) had a role in hydrocarbon alternation.