Development of a testing protocol for oil solidifier effectiveness evaluation

Chemical countermeasures for oil spill remediation have to be evaluated and approved by the U.S. Environmental Protection Agency before they may be used to remove or control oil discharges. Solidifiers are chemical agents that change oil from a liquid to a solid by immobilizing the oil and bonding the liquid into a solid carpet-like mass with minimal volume increase. Currently, they are listed as Miscellaneous Oil Spill Control Agent in the National Contingency Plan and there is no protocol for evaluating their effectiveness. An investigation was conducted to test the oil removal efficiency of solidifiers using three newly developed testing protocols. The protocols were qualitatively and quantitatively evaluated to determine if they can satisfactorily differentiate effective and mediocre products while still accounting for experimental error. The repeatability of the three protocols was 15.9, 5.1, and 2.7 %. The protocol with the best performance involved measuring the amount of free oil remaining in the water after the solidified product was removed using an ultraviolet–visible spectrophotometer and it was adopted to study the effect of solidifier-to-oil mass ratio, mixing energy, salinity, and beaker size (i.e., area affected by the spill) on solidifier efficiency. Analysis of Variances were performed on the data collected and results indicated that the beaker size increased spreading, which reduced removal efficiency. Mixing speed appears to impart a ceiling effect with no additional benefit provided by the highest level over the middle level. Salinity was found to be mostly an insignificant factor on performance

Autonomous water sampler for oil spill response

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gomez-Ibanez, D., Kukulya, A. L., Belani, A., Conmy, R. N., Sundaravadivelu, D., & DiPinto, L. Autonomous water sampler for oil spill response. Journal of Marine Science and Engineering, 10(4), (2022): 526, https://doi.org/10.3390/jmse10040526.A newly developed water sampling system enables autonomous detection and sampling of underwater oil plumes. The Midwater Oil Sampler collects multiple 1-L samples of seawater when preset criteria are met. The sampler has a hydrocarbon-free sample path and can be configured with several modules of six glass sample bottles. In August 2019, the sampler was deployed on an autonomous underwater vehicle and captured targeted water samples in natural oil seeps offshore Santa Barbara, CA, USA.This work was supported by the United States Bureau of Safety and Environmental Enforcement under contract number E18PG00001

Characterization of solidifiers used for oil spill remediation

The physical characteristics and chemical composition of oil spill solidifiers were studied, and correlation of these properties with product effectiveness enabled determination of characteristics that are desirable in a good solidifier. The analyses revealed that the commercial products were primarily comprised of organic polymers and a few trace elements. A natural sorbent, which was composed entirely of plant based matter, was also evaluated, and it had the highest oil removal capacity, but it did not produce a solid mat-like final product. Generally, solidifiers with a carbonate group, pore size greater than 5 mum, and bulk densities lower than 0.3 g cm(-3) were found to have better efficiency and produced a cohesive rubbery final product that facilitated removal compared to sorbents. The importance of bulk density and pore size in the performance of the solidifier suggest that the primary mechanism of action was likely physical sorption

Round-Robin Testing of a New EPA Solidifier Effectiveness Protocol

ABSTRACT A new laboratory testing protocol for evaluating effectiveness of solidifiers in removing crude oil slicks on the water surface has been developed by the U.S. Environmental Protection Agency (EPA). Since an assessment of a testing protocol requires validation through an inter laboratory study with several independent research partners, a round-robin test was performed by five operators across two laboratories. The protocol was qualitatively and quantitatively evaluated to determine if it can satisfactorily differentiate product effectiveness, while still accounting for experimental and operational errors. Each operator evaluated the efficiency of six solidifier products with Arabian Light, Endicott and IFO 120 crude oils. All the experiments were carried out in triplicates and, additionally, an oil alone control sample was run for quality control purposes. The five operators were provided with all the supplies required to conduct the experiment and a detailed standard operating procedure. The results were collected and analyzed statistically to quantify repeatability and reproducibility. The average repeatability and reproducibility standard deviations were 5.1, 2.7, and 3.3% and 11.2, 10.1, and 13.1% for Arabian Light, Endicott and IFO, respectively. The within-operator error was ≤ 5% regardless of operator and oil type. Due to the difficulty and uncertainty associated with the separation of the solidified and un-solidified mass, the between-operator error was around 10%. The oil alone control had an average repeatability and reproducibility standard deviation of 4.8 and 6.1%, respectively. The variability among operators was also examined with h-statistics and the differences in operator means were found to be statistically insignificant. The variability is deemed acceptable for purposes of differentiating effective from ineffective solidifier products in the laboratory. The results from this round robin experiment will serve as an initial screening tool for the solidifier products in the market and will also help response teams determine the desirability and appropriateness of using a specific solidifier for oil spill remediation.</jats:p

Parametric study to determine the effect of temperature on oil solidifier performance and the development of a new empirical correlation for predicting effectiveness

Temperature can play a significant role in the efficacy of solidifiers in removing oil slicks on water. We studied and quantified the effect of temperature on the performance of several solidifiers using 5 different types of oils under a newly developed testing protocol by conducting experiments in constant temperature rooms set at 22. °C and 5. °C. The results indicated that solidifier efficiency decreased substantially at the lower temperature, especially at lower application rates. The removal efficiency of the solidifier was in general directly proportional to temperature, except for the heavier oils, where removal by attachment was observed. Solidifier products with lower powder bulk density exhibited the best removal effectiveness. Analysis of experimental data yielded empirical correlations involving certain operational variables such as application rate, temperature, solidifier property (bulk density), and oil property (viscosity). Regression analysis was used to fit a mathematical model to the experimental solidifier effectiveness data. © 2015 Elsevier Ltd

Microbial degradation of Cold Lake Blend and Western Canadian select dilbits by freshwater enrichments

Treatability experiments were conducted to determine the biodegradation of diluted bitumen (dilbit) at 5 and 25 °C for 72 and 60 days, respectively. Microbial consortia obtained from the Kalamazoo River Enbridge Energy spill site were enriched on dilbit at both 5 (cryo) and 25 (meso) ºC. On every sampling day, triplicates were sacrificed and residual hydrocarbon concentrations (alkanes and polycyclic aromatic hydrocarbons) were determined by GCMS/MS. The composition and relative abundance of different bacterial groups were identified by 16S rRNA gene sequencing analysis. While some physicochemical differences were observed between the two dilbits, their biodegradation profiles were similar. The rates and extent of degradation were greater at 25 °C. Both consortia metabolized 99.9% of alkanes; however, the meso consortium was more effective at removing aromatics than the cryo consortium (97.5 vs 70%). Known hydrocarbon-degrading bacteria were present in both consortia (Pseudomonas, Rhodococcus, Hydrogenophaga, Parvibaculum, Arthrobacter, Acidovorax), although their relative abundances depended on the temperatures at which they were enriched. Regardless of the dilbit type, the microbial community structure significantly changed as a response to the diminishing hydrocarbon load. Our results demonstrate that dilbit can be effectively degraded by autochthonous microbial consortia from sites with recent exposure to dilbit contamination

Effect of Salinity on the Effectiveness of Solidifiers for Crude Oil Spill Remediation

ABSTRACT A laboratory investigation was conducted to test the effectiveness of solidifiers with fresh water and artificial seawater using Prudhoe Bay Crude oil. Experiments were designed to study the effects of salinity, solidifier type, solidifier-to-oil mass ratio (SOR), mixing energy and beaker size using five solidifiers. The U.S. Environmental Protection Agency is developing a protocol for testing the effectiveness of solidifiers in a laboratory setting. This involves measuring the amount of free oil remaining in the water after the solidified product is removed using an ultraviolet–visible spectrophotometer. For these experiments, 0.25 mL of oil was added to salinized beaker containing 80 mL of water. Milli-Q water and sterile GP2 seawater were used as the exposure media. The mass of the solidifier was changed depending on the SOR. Each of the solidifier was added to a slick of crude oil on water. After stirring the mixture for 30 minutes, the solidifier was removed. The water with the remaining oil was transferred from the beaker to 250 mL separatory funnel. The solution in the funnel was extracted three times with 20 mL of dichloromethane and the final volume adjusted to 60 mL. The extracted samples were analyzed for oil content with an Agilent 8452 ultraviolet–visible spectrophotometer. All experiments were carried out in triplicate. An analysis of variance (ANOVA) was performed on the data collected, which helped quantify the main and interactive effects of the variables. Salinity of the water was mostly found to be an insignificant factor. Results indicated that SOR and solidifier type are the most important variables affecting removal efficiency.</jats:p