Remediation of Oily Sludge- and Oil-Contaminated Soil from Petroleum Industry: Recent Developments and Future Prospects

Bioremediation of heavy oily sludge: a microcosms study

Oily sludge is a residue from the petroleum industry composed of a mixture of sand, water, metals, and high content of hydrocarbons (HCs). The heavy oily sludge used in this study originated from Colombian crude oil with high density and low American Petroleum Institute (API) gravity. The residual waste from heavy oil processing was subject to thermal and centrifugal extraction, resulting in heavy oily sludge with very high density and viscosity. Biodegradation of the total petroleum hydrocarbons (TPH) was tested in microcosms using several bioremediation approaches, including: biostimulation with bulking agents and nutrients, the surfactant Tween 80, and bioaugmentation. Select HC degrading bacteria were isolated based on their ability to grow and produce clear zones on different HCs. Degradation of TPH in the microcosms was monitored gravimetrically and with gas chromatography (GC). The TPH removal in all treatments ranged between 2 and 67%, regardless of the addition of microbial consortiums, amendments, or surfactants within the tested parameters. The results of this study demonstrated that bioremediation of heavy oily sludge presents greater challenges to achieve regulatory requirements. Additional physicochemical treatments analysis to remediate this recalcitrant material may be required to achieve a desirable degradation rate.

Hierarchical porous mussel shells as soil amendment for oil spill remediation

In this work, a new type of micromesoporous substance was prepared with fatty alcohol-polyoxyethylene ether (AEO) surfactant freezing penetration and pyrolysis using shells as raw materials. The obtained material exhibited good adsorbability and could be added to oil-contaminated soil to adsorb the pollutant, which resulted in the regeneration of the initially polluted soil. It was determined that the main component of the developed substance was CaCO₃. Importantly, the conducted experiments revealed that the obtained mussel micromesoporous material displayed certain adsorption effects toward petroleum hydrocarbons in a diesel solution. Moreover, it was found that chemical adsorption was more optimal than physical adsorption. The soil remediation effect was the best when the content of the mussel micromesoporous material in the soil was 400 g/kg. Under these conditions, the removal rate of petroleum hydrocarbon was established at 49.38%. This study indicated that micromesoporous material has great potential in the application of oil contaminated soil remediation.

Petroleum sludge treatment and disposal techniques: a review

Petroleum sludge is a solid emulsified waste and contaminant commonly produced in the petroleum industry. In the recent past, there has been increased business growth in the oil sector, resulting in increased volumes of oily sludge characterized by high viscosity and toxicity. Therefore, sludge treatment before discarding is extremely necessary. This review seeks to highlight various conventional and evolving approaches in the treatment, recovery, and disposal of petroleum sludge and assess their suitability under various conditions.

Optimization of Process Parameters of Rhamnolipid Treatment of Oily Sludge Based on Response Surface Methodology

Oily sludge is a hazardous waste. If not handled properly, it can not only pollute the environment but also endanger human health. This study is the first to use a response surface method to optimize the main parameters of rhamnolipid-based recovery of oil from oily sludge. Using rhamnolipids as the cleaning agent and the oil recovery fraction as the evaluation index, the factors affecting the cleaning efficiency of oily sludge were optimized. The aforementioned sludge was obtained from the Tarim Oilfield. A single-factor experiment was conducted to determine the optimal range of the dosage, liquid-solid ratio, pH value, and time. The Box-Behnken response surface method was used to investigate the influence of each variable on the residual oil fraction of the oily sludge, and the dosage, pH value, and time were found to have a significant impact. The model optimization results show that the best process conditions for rhamnolipid-based recovery of oil are as follows: rhamnolipid dosage = 167.785 mg/L; liquid-solid ratio = 4.589:1; pH = 9.618; time = 1.627 h. Under optimal conditions, the model-predicted oil recovery fraction and the actual oil recovery fraction were 85.15 and 82.56%, respectively; the relative error between the predicted and the actual values was 2.59%. These results indicate that the model results are reliable. The solid residue after the cleaning was also analyzed to gain an in-depth understanding of the cleaning process. This study determined the feasibility of a rhamnolipid-based solution for the treatment of oily sludge and oil-contaminated soil.