Characterization of the physical and weathering properties of low sulfur fuel oil (LSFO) and its spreading on water surface

Mycoremediation of Louisiana sweet crude oil with Pleurotus ostreatus and nutrient amendments

Oyster mushrooms (Pleurotus ostreatus) are known to metabolize polycyclic aromatic hydrocarbons in petroleum crude oil, making them candidates for oil spill remediation studies. This work aimed to assess P. ostreatus for its hydrocarbon degradation potential in estuarine conditions. In vitro experiments evaluated nutrient amendments based on P. ostreatus carbon: nitrogen: phosphorous (C: N: P) ratios to optimize mycelium growth, increase degradation efficiencies, and reduce potential nutrient runoff in broader applications. Image analysis was used to track mycelium growth response to various salinities, nutrient amendments, and oil types. Subsequent evaluation of alterations within the saturate, aromatic, resin, and asphaltene (SARA) fractions constituting Louisiana sweet crude (LSC) was conducted via SARA analysis. Results indicate that P. ostreatus mycelium tolerates estuarine salinities, with maximum growth between 5 and 15‰. Relative to 0‰, growth was reduced at salinities >25‰, but positive growth was still observed. Nutrient amendments significantly increased growth over 7 days relative to untreated samples (p < 0.0001). The combination of ammonium chloride and potassium phosphate yielded optimal mycelium growth after 7 days. Mycelium and nutrients significantly altered saturate (p = 0.0015) and asphaltene (p = 0.0124) fractions in LSC. This study suggests that mycelium growth is viable under estuarine salinities and can be enhanced with nutrient amendments. Introducing nutrient factors was shown to influence oil degradation. Results also indicate that mycelium can reduce recalcitrant oil fractions. Thus, this study highlights the adaptability of P. ostreatus to estuarine conditions and its response to nutrient amendments, all while offering a promising approach to crude oil bioremediation.

Hierarchically-structured ratchet skimmer with superhydrophilicity for continuous recovery of high-viscosity oil

Oil spill accidents have series environmental and economic impacts, increasing the demand for efficient technologies to recover oil from contaminated waters. In this study, a hierarchically structured ratchet surface with superhydrophilicity was presented as a novel oil skimming mechanism for the recovery of high-viscosity oil, particularly low-sulfur fuel oil (LSFO), which has recently been used as marine fuel in open water environments. The interaction between the superhydrophilic ratchet and oil provides favorable conditions for oil retention at the water surface. The hierarchical structure minimizes contact between oil and the skimmer surface, allowing separation without a scraper, even at higher speeds. In addition, the ratchet skimmer generates a water surface flow near the skimmer, driving oil to the drum and improving skimming performance. The skimmer achieved a recovery efficiency of almost 100 % under various experimental conditions with an LSFO viscosity of up to 12,000 cSt.

Assessment of oil vertical diffusion in waters following an oil spill incident in an urban inland waterway

Accidental oil spills can have a serious impact on water bodies. While most current studies have focused on waves, few have examined water flows, which represent the most common hydrodynamic environment in urban inland waterways. In this study, 12 hydrodynamic conditions were constructed, and the oil vertical diffusion characteristics under hydrodynamic conditions were investigated by measuring oil concentration and oil droplet size distribution at different depths. The main findings include: (1) Oil concentration decays exponentially along the vertical direction, the related parameters follow power and quadratic functions in relation to mean flow velocity, respectively; (2) Oil droplet size distribution was influenced by hydrodynamic characteristics, mean flow velocity was significantly positively correlated with its distribution range; (3) Oil droplet size distribution patterns at different depths were similar, in line with the characteristics of Rosin-Rammler distribution. Based on experimental data, a set of models was constructed to describe and predict the vertical distribution of oil concentration and oil droplet size distribution under hydrodynamic conditions. This study not only reveals the characteristics of oil vertical diffusion under hydrodynamic conditions, but also provides a quantitative framework for understanding the relevant features, which is helpful for the response to the oil spill accident in urban inland waterways.

Prediction of the marine spreading of low sulfur fuel oil using the long short-term memory model trained with three-phase numerical simulations

In this study, we focus on the development and validation of a deep learning (long short-term memory, LSTM)-based algorithm to predict the accidental spreading of LSFO (low sulfur fuel oil) on the water surface. The data for the training was obtained by numerical simulations of artificial geometries with different configurations of islands and shorelines and wind speeds (2.0-8.0 m/s). For simulating the spread of oils in O(102) km scales, the volume of fluid and discrete phase models were adopted, and the kinematic variables of particle location, particle velocity, and water velocity were collected as input features for LSTM model. The predicted spreading pattern of LSFO matched well with the simulation (less than 10 % in terms of the mean absolute error for the untrained data). Finally, we applied the model to the Wakashio LSFO spill accident, considering actual geometry and weather information, which confirmed the practical feasibility of the present model.

Development of rapid and effective oil-spill response system integrated with oil collection, recovery and storage devices for small oil spills at initial stage: From lab-scale study to field-scale test

In the present study, through the laboratory-to-field scale experiments and trials, we report the development and evaluation of an integrated oil-spill response system capable of oil collection, recovery (separation), and storage, for a timely and effective response to the initial stage of oil-spill accidents. With the laboratory-scale experiments, first, we evaluate that the water-surface waves tend to abate the oil recovery rate below 80% (it is above 95% for the optimized configuration without the waves), which is overcome by installing the hydrophilic (and oleophobic) porous structures at the inlet and/or near the water outlet of the separator. In the follow-up meso-scale towing tank tests with a scaled-up prototype, (i) we optimize the maneuverability of the assembled system depending on the speed and existence of waves, and (ii) evaluate the oil recovery performance (more than 80% recovery for the olive oil and Bunker A fuel oil). Although more thorough investigations and improvements are needed, a recovery rate of over 50% can be achieved for the newly enforced marine fuel oil (low sulfur fuel oil, LSFO) that was not targeted at the time of development. Finally, we perform a series of field tests with a full-scale system, to evaluate the rapid deployment and operational stability in the real marine environment. The overall floating balance and coordination of each functional part are sustained to be stable during the straight and rotary maneuvers up to the speed of 5 knots. Also, the collection of the floating debris (mimicking the spilled oil) is demonstrated in the field test. The present system is now being tested by the Korea Coast Guard and we believe that it will be very powerful to prevent the environmental damage due to the oil spills.