Preliminary Study on Treatment of Contaminated Groundwater from the Taylorville Gasifier Site

Groundwater and soil at the site of an abandoned coal gasification plant in Taylorville, Illinois have been contaminated with compounds associated with coal conversion process waters. A preliminary study to assess the feasibility of using ethanol as a means of increasing the solubility of compounds adsorbed within the soil matrix followed by treatment of the ethanol/groundwater extract in an expanded-bed anaerobic granular activated carbon (GAC) reactor was conducted. Results of the study indicate that compounds in the groundwater are highly adsorb able on GAC, and do not interfere with the anaerobic degradation of ethanol in the reactor. Soil extractions with varying ethanol/water ratios were able to remove many additional low water solubility compounds from the soil.ENR Contract Number HWR87035published or submitted for publicationis peer reviewe

Reduction of aqueous free chlorine with granular activated carbon

A surface reaction rate expression was developed to describe the heterogeneous reaction between aqueous free chlorine and granular activated carbon. This expression was then incorporated into a pore diffusion model and the relevant partial differential equations with the corresponding boundary conditions were solved for the case of (1) a constant concentration batch reactor and (2) a closed batch reactor. The solutions were then compared to similar batch data in order to evaluate the pore model constants. A packed bed reactor model was then solved using the rate information from the batch mathematical models and experimental data. The predicted results from the packed bed model were then compared to experimental results which were collected using applicable conditions. The effect of particle size on the rate of removal of free chlorine was investigated both in batch and packed bed column form. The effect of pH on the rate of reaction was studied in the pH range of 4-10. It was found that the pH only affects the rate insofar as it affects the distribution of free chlorine between OCl¯ and HOCl. Temperature effects were also studied in the range 2°-35°C. The effect of temperature on the surface dissociation rate constant was found to correspond to the Arrhenius law.U.S. Department of the InteriorU.S. Geological SurveyOpe

Partially Acetylated Sugarcane Bagasse for Wicking Oil from Contaminated Wetlands

Sugarcane bagasse was partially acetylated to enhance its oil-wicking ability in saturated environments while holding moisture for hydrocarbon biodegradation. The water sorption capacity of raw bagasse was reduced fourfold after treatment, which indicated considerably increased hydrophobicity but not a limited capability to hold moisture for hydrocarbon biodegradation. Characterization results by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and surface area analyzer suggested that treated bagasse exhibited enhanced hydrophobicity and surface area. Oil wicking test results indicate that treated bagasse is more effective in wicking oil from highly saturated environments than raw bagasse and suggest that application of this material in remediation of oil spills in highly saturated wetlands is promising

Microbial attachment properties in expanded-bed, activated carbon anaerobic filters

A completely mixed, expanded-bed, anaerobic granular activated carbon filter was operated on synthetic wastewaters in which acetate was the only organic carbon source. Steady-state performance was achieved for two influent acetate concentrations: namely, 800 and 1,600 mg/L. Steady-state removal efficiencies in chemical oxygen demand, dissolved organic carbon, and acetate exceeding 96, 97, and 98 percent were obtained, respectively. A steady-state biofilm kinetic model was employed for analyzing the two sets of "steady-state" data. The modeling effort was successful in describing trends and effects; however, insufficient data were available to properly calibrate the model and obtain reliable values for the parametric constants.U.S. Department of the InteriorU.S. Geological SurveyOpe

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

Anaerobic Treatment of Army Ammunition Production Wastewater Containing Perchlorate and RDX

Perchlorate is an oxidizer that has been routinely used in solid rocket motors by the Department of Defense and National Aeronautics and Space Administration. Royal Demolition Explosive (RDX) is a major component of military high explosives and is used in a wide variety of munitions. Perchlorate bearing wastewater typically results from production of solid rocket motors, while RDX is transferred to Army industrial wastewaters during load, assemble and pack operations for new munitions, and hot water or steam washout for disposal and deactivation of old munitions (commonly referred to as demilitarization, or simply demil). Biological degradation in Anaerobic Fluidized Bed Reactors (AFBR), has been shown to be an effective method for the removal of both perchlorate and RDX in contaminated wastewater. The focus of this study was to determine the effectiveness of removal of perchlorate and RDX, individually and when co-mingled, using ethanol as an electron donor under steady state conditions. Three AFBRs were used to assess the effectiveness of this process in treating the wastewater. The performance of the bioreactors was monitored relative to perchlorate, RDX, and chemical oxygen demand removal effectiveness. The experimental results demonstrated that the biodegradation of perchlorate and RDX was more effective in bioreactors receiving the single contaminant than in the bioreactor where both contaminants were fed

Batch Tests To Determine Activity Distribution and Kinetic Parameters for Acetate Utilization in Expanded-Bed Anaerobic Reactors

Batch tests to measure maximum acetate utilization rates were used to determine the distribution of acetate utilizers in expanded-bed sand and expanded-bed granular activated carbon (GAC) reactors. The reactors were fed a mixture of acetate and 3-ethylphenol, and they contained the same predominant aceticlastic methanogen, Methanothrix sp. Batch tests were performed both on the entire reactor contents and with media removed from the reactors. Results indicated that activity was evenly distributed within the GAC reactors, whereas in the sand reactor a sludge blanket on top of the sand bed contained approximately 50% of the activity. The Monod half-velocity constant (K(s)) for the acetate-utilizing methanogens in two expanded-bed GAC reactors was searched for by combining steady-state results with batch test data. All parameters necessary to develop a model with Monod kinetics were experimentally determined except for K(s). However, K(s) was a function of the effluent 3-ethylphenol concentration, and batch test results demonstrated that maximum acetate utilization rates were not a function of the effluent 3-ethylphenol concentration. Addition of a competitive inhibition term into the Monod expression predicted the dependence of K(s) on the effluent 3-ethylphenol concentration. A two-parameter search determined a K(s) of 8.99 mg of acetate per liter and a K(i) of 2.41 mg of 3-ethylphenol per liter. Model predictions were in agreement with experimental observations for all effluent 3-ethylphenol concentrations. Batch tests measured the activity for a specific substrate and determined the distribution of activity in the reactor. The use of steady-state data in conjunction with batch test results reduced the number of unknown kinetic parameters and thereby reduced the uncertainty in the results and the assumptions made

Biological transformation pathways of 2,4-dinitro anisole and N-methyl paranitro aniline in anaerobic fluidized-bed bioreactors

The US Army is evaluating new, insensitive explosives to produce safer munitions. Two potential new components are 2,4-dinitro anisole (DNAN) and N-methyl paranitro aniline (MNA), which would eventually make their way to waste streams generated in the production and handling of new munitions. The effectiveness of anaerobic fluidized-bed bioreactors (AFBB) was studied for treatment and transformation of these two new chemical components in munitions. Each compound was fed into a separate reactor and monitored for removal and transformation, using ethanol as the electron donor. The results show that both were degradable using the AFBB system. DNAN was found to transform into diaminoanisole and MNA was found to transform into N-methyl-p-phenylenediamine. Both of these by-products appeared to form azobond polymers after exposure to air. To test the resilience of the reactors, the compounds were removed from the feed streams for 3 week and then reintroduced. DNAN showed that a re-acclimation period was necessary for it to be degraded again, while MNA was removed immediately upon reintroduction. The AFBB technology was shown here to be an effective means of removing the new munitions, but produce secondary compounds that could potentially be just as harmful and require further study