Clint Williford

Dissolution and transport of 2,4-DNT and 2,6-DNT from M1 propellant in soil

Live-fire training exercises can result in particulate propellant contamination on military training ranges and can potentially contaminate ground water. This study was conducted to evaluate dissolution of the 2,4-dinitrotoluene (2,4-DNT) and 2,6-dinitrotoluene (2,6-DNT) from the propellant formulation, M1 (87.6% nitrocellulose, 7.3% 2,4-DNT, 0.57% 2,6-DNT, 1.06% diphenylamine, 3.48% dibutyl phthalate) and their subsequent transport in soil. Batch dissolution studies were followed by saturated column transport experiments. Neat, dissolved 2,4-DNT, and M1 in solid and dissolved forms were used as influent to columns filled with Plymouth loamy sand (mesic, coated Typic Quartzipsamments) from Camp Edwards, MA. Dissolution rates and other fate and transport parameters were determined using the HYDRUS-1D code. M1 dissolution was limited by DNT diffusion from the interior of the pellet, resulting in an exponential decrease in dissolution rate with time. The HYDRUS-1D model accurately described release and transport of 2,4- and 2,6-DNT from M1 propellant. Dissolution rates for M1 in the stirred reactor and column studies were similar, indicating that batch dissolution rates are potentially useful to represent field conditions.

Vertical column hydroclassification of metal-contaminated soils.

The purpose of this work was to reduce soil volumes requiring aggressive treatment. A second purpose was to determine differences in separation due to distinct forms of the metal contamination and soil texture. The objectives were to apply hydroclassification and find mass and metal-contaminant distribution of four soils contaminated with heavy metals from firing ranges, a small arms incinerator, and an electroplating operation. The soils were slurried in water, sieved, and exposed to upward flowing water to separate the soil particles into four nominal size ranges. The popping furnace soil exhibited substantial lead among all particle size fractions. The firing range soils exhibited bimodal distributions. The electroplating soil exhibited a strong concentration of metals toward the <63 microm fraction. Attrition scrubbing moderately improved the enrichment of metals in several fractions. Extraction revealed the lead and chromium in the electroplating soil to be relatively immobile. These results suggest metal distributions are influenced by the different mechanisms of introduction into the soil. They also help to predict performance of processing options such as sieving hydroclassification and attrition scrubbing.

Desulfurization and Emissions Control

Desulfurization removes elemental sulfur and its compounds from solids, liquids, and gases. Predominantly, desulfurization involves the removal of sulfur oxides from flue gases, compounds of sulfur in petroleum refining, and pyritic sulfur in coal cleaning. This chapter discusses the following topics: 1. Sulfur pollution (sulfur oxides, hydrogen sulfide, and organic sulfur pollutants). 2. The US Air Quality Act. 3. Solid-phase desulfurization (coal cleaning, gasification, and liquefaction). 4. Liquid-phase desulfurization (acid-lake restoration for H2SO4 removal and groundwater decontamination for H2S removal). 5. Gas-phase desulfurization (SO x and H2S removals from air emission streams).

Extraction of TNT from aggregate soil fractions

Past explosives manufacture, disposal, and training activities have contaminated soil at many military facilities, posing health and environmental risks through contact, potential detonation, and leaching into ground water. While methods have been confirmed for extraction and measuring explosives concentration in soil, no work has addressed aggregate size material (the >2 mm gravel and cobbles) that often occurs with the smaller soil fractions. This paper describes methods and results for extraction and measurement of TNT (2,4,6-trinitrotoluene) in aggregate material from 1/2 to 2-1/1 from a WWII era ammunition plant. TNT was extracted into acetonitrile by both Soxhlet and ultrasonic extraction methods. High pressure liquid chromatography analyses of extracts showed expected variation among samples. Also effective extraction and determination of TNT concentration for each aggregate size fraction was achieved.

FUNGAL-INDUCED REDISTRIBUTION OF KRAFT LIGNIN MOLECULAR WEIGHT BY MULTI-ANGLE LASER LIGHT SCATTERING

Culture broths from Phanerochaete chrysosporium and Trametes cingulata, combined with co-factors such as hydrogen peroxide, dithiothreitol, copper, iron, and manganese ions were examined for the ability to modify lignin structure. High-performance size exclusion chromatography (HP-SEC) coupled to multi-angle laser light scattering (MALLS) detection was used to determine the effect of several white rot fungi, pH values, enzymes, and co-factors on the molecular weight distribution of treated kraft lignin. The analytical procedure tracked changes in molecular weight distribution, radius of gyration, and hydrodynamic radius. Results showed changes in the molecular weight distribution of lignin components when treated with combinations of factors. The induced cultures showed more lignin depolymerization for the specific lignin samples in which they were initially grown. The distribution in the radius of gyration became narrower with time, indicating that molecular conformation changed to a more uniform molecular shape. H2O2 and DTT showed the most significant changes in lignin molecular weight distribution.

Formation of Manganese Oxide Coatings onto Sand for Adsorption of Trace Metals from Groundwater

Manganese oxide (MnO) occurs naturally in soil and has a high affinity for trace metals adsorption. In this work, we quantified the factors (pH; flow rate; use of oxidants such as bleach, HO, and O; initial Mn(II) concentrations; and two types of geologic media) affecting MnO coatings onto Ottawa and aquifer sand using batch and column experiments. The batch experiments consisted of manual and automated titration, and the column experiments mimicked natural MnO adsorption and oxidation cycles as a strategy for in situ adsorption. A Pb solution of 50 mg L was passed through MnO-coated sand at a flow rate of 4 mL min to determine its adsorption capacity. Batch experimental results showed that MnO coatings increased from pH 6 to 8, with maximum MnO coating occurring at pH 8. Regarding MnO coatings, bleach and O were highly effective compared with HO. The Ottawa sand had approximately twice the MnO coating of aquifer sand. The sequential increase in initial Mn(II) concentrations on both sands resulted in incremental buildup of MnO. The automated procedure enhanced MnO coatings by 3.5 times compared with manual batch experiments. Column results showed that MnO coatings were highly dependent on initial Mn(II) and oxidant concentrations, pH, flow rate, number of cycles (h), and the type of geologic media used. Manganese oxide coating exceeded 1700 mg kg for Ottawa sand and 130 mg kg for aquifer sand. The Pb adsorption exceeded 2200 mg kg for the Ottawa sand and 300 mg kg for the aquifer sand.

Low-Temperature Thermal Treatment Processes

There are two kinds of thermal processes for sludge treatment: (a) heat conditioning: a conditioning process which prepares sludge (i.e., mainly biosolids) for dewatering on filter presses or vacuum filters without the use of chemicals and (b) heat-drying: a process which evaporates water from sludge by thermal means (1)–(11). Ambient air-drying processes are dealt with in another two chapters: “Evaporation processes” and “Drying beds.”

High Temperature Thermal Processes

Since the early 1900s, high temperature processes have been used for combustion of municipal wastewater solids. The popularity of these processes has fluctuated greatly because of their adaptation from the industrial combustion field. In the past, combustion of wastewater solids was both practical and inexpensive. Solids were easily dewatered, and the fuel required for combustion was cheap and plentiful. In addition, air emission standards were virtually nonexistent.

PROBABILISTIC MODELING OF OXYGEN TRANSPORT IN BRAIN TISSUE

A three-dimensional model of a subregion of the microcirculation was developed. The model employed parallel probabilistic distributions of reaction and convection of oxygen. A Greens function solution to oxygen transport in this system was derived and applied in a series of dynamic solutions on a minicomputer. Results include the transient response of oxygen tension at grid points throughout the system and a correlation of the oxygen demand and surplus supply. Results clearly represent anticipated oxygen partial pressure behavior trends of a countercurrent flow system and in pertinent ways compared favorably with the results obtained by previous investigators. The technique is conservative and employs from 2,000 to 3,600 time steps to achieve precision of seven significant figures. Excellent stability was observed as well. The simulation provides a reliable means to represent the transient response of oxygen partial pressure in a three-dimensional system. Case studies show effects of changing arterial oxygen partial pressure as well as the importance in this system of the convection of dissolved oxygen. It is concluded that the system adequately simulates the anticipated broad profiles of a probabilistically distributed system and provides a rather original insight into neuronal viability through a correlation of oxygen supply and demand. Adaptation of such a complex, dynamic, three-dimensional stimulation to a minicomputer is a step toward simulation of more sophisticated geometries.