Browsing by Subject "Hazardous wastes"
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Item An environmentally benign supercritical fluid process for printed wiring board recycling(Texas Tech University, 2004-12) Yuan, YingchunThis research is focused on development of an alternative recycling process for printed wiring boards (PWBs). With huge amounts of electronic products becoming obsolete each year, the numerous kinds of PWBs from these obsolete electronics cause grave environmental concerns in both society and governmental agencies due to their toxic material composition and complicated physical structures. Although some techniques such as incinerations and shredding are currently employed for recycling PWB scraps by hundreds of electronic recyclers, these techniques are not efficient from environmental and economic views. This project is proposed to address both the environmental and economic demands for PWB recycling processes. In the research, supercritical fluid CO2 is employed to treat the PWB scraps which will cause decomposition of various resins in PWB substrates. Since resins are the bond materials between PWB layers, the complete decomposition of all resins would automatically cause the delaminating of PWB boards when the process is subject to rapid depressurizations to induce sufficient forming effect. To study the supercritical fluid treatment effect, weight reduction percent of PWBs is used as index for measuring resin decomposition effect. Five kinds of bare PWBs from Canada and USA companies are used as specimen in the experiment which is studied based on the factorial experiment design method. In addition, water is added as an environmental benign co-solvent to supercritical fluid CO2 and its effect in enhancing the interactions is investigated. From the systematic study, it is found that temperature is the most influential factor on the PWB decomposition effect. Pressure plays an importance role but not critical when it is in effective regions. Three hours is good enough for a complete interaction between PWBs and SCF CO2. Addition of 7 mole % of water can greatly enhance the delaminating effect and surface cracking during the reaction process, which is significant for real application of the process in future.Item Clean-up of biological agents using arcjet plasma sources(Texas Tech University, 1999-05) Anumalla, Naveen KumarBiological agents can be destructed using some of the general techniques, like treating with formaldehyde, or moist heat, and radioactive materials will decay with the passage of sufficient time. But these conventional methods are not readily adoptable to large surfaces, especially in the open air, for rapid clean up. The availability of destruction technique for hazardous biological agents, which is presented here, would be particularly helpful in the destruction of battlefield chemical and biological warfare agents. This thesis provides one of the many destruction procedures for a particular type of bacteria present in the biological agents. The purpose of decontamination is achieved by evaluating thermal plasmas for use in the destrucdon of deadly chemical and biological warfare agents. The procedure consists of employing an electric arc to establish plasma forming gas plume, to which the spilled biological agents are exposed and this kills the harmful agents. The two different approaches used here are nitrogen plasma, and a nitrogen and argon plasma arcjet. The proposed concept is to install a row of similar nozzles across the front of a truck, which will cover a specified amount of area on the ground. The truck runs over the area and destroys the biological agents. Additionally, the methods developed have application in the destruction of medical wastes; hazardous industrial wastes and in the destruction of hazardous materials associated with worldwide demilitarization activities.Item Evaluation of an aerated soil reactor for the degradation of a hazardous organic waste(Texas Tech University, 1989-05) Brashear, Robert W.Not availableItem In-situ degradation of high explosives(Texas Tech University, 1999-08) Brown, Justin HeathThe purpose of this research is to develop an in situ method to biodegrade high explosives in the vadose zone. The research project involves the construction of an experimental field site to force an anaerobic treatment zone and thus stimulate indigenous microorganisms to biodegrade the HE. The desired level of treatment is to reduce the HE concentrations to below the RRS2 values.Item Laboratory studies indicating the potential for bioremediation of high explosives in soil at the Pantex Plant(Texas Tech University, 1998-12) Medlock, Walter NThe main purpose of this thesis is to provide information in support ofthe field study. In May of 1998, eight, 30-ft wells were constmcted at the field study site to facilitate the gas injection and extraction procedure. The core samples from these wells were preserved and transported to Texas Tech University where they were analyzed with the following objectives in mind: (1) delineate the extent of HE contamination at the field study site, (2) determine if microbial (metabolic) activity is present in the soil, (3) enumerate the anaerobic microbial population, and (4) examine the relationships among HE concentration, metabolic activity, and microbial population.Item Microwave-induced plasma destruction of trichloroethylene(Texas Tech University, 1993-12) LaDue, Douglas EugenePublic concern over environmental problems has forced the government to pass regulations controlling the safe disposal of chemical wastes. One particular class of hazardous waste that requires a safe disposal method is chlorinated hydrocarbons (CHCs). The US Environmental Protection Agency regards incineration as the best available method to destroy CHCs. However, there are several technical difficulties associated with the use of incineration to destroy CHCs. Therefore, there is considerable interest in developing alternative methods to destroy CHCs. This work investigated the destruction of CHCs in a microwave-induced plasma reactor as an alternative to incineration of CHCs. Trichloroethylene (TCE) was selected as a surrogate to represent the general class of CHC wastes. TCE was reacted with oxygen and water in a microwave-induced plasma in an air environment at atmospheric pressure. The first part of the experimental work was directed at identifying the range of operating conditions where a plasma could be sustained. Three operating parameters were investigated: microwave input power, and the air, argon and water feed concentrations in the feed. Based on the results of this part, "maps" showing the operating conditions where a plasma could be sustained were prepared. It was found that sustaining a plasma in an air environment at atmospheric pressure while introducing the reactants TCE and water required an input microwave power greater than 600 W. Unfortunately, it was also found that operating the experimental system at an input microwave power greater than 600 W resulted in the mechanical failure of the reactor. Therefore, in order to lower the power requirements of the reaction medium, an argon and air mixture was used as the carrier gas for the TCE destruction experiments. The second part of the experimental work was the investigation of the reaction of TCE with oxygen and water in a microwave-induced plasma at atmospheric pressure. It was found that the plasma could be sustained, the TCE conversion was greater than 98%. The products of the TCE destruction were mainly carbon dioxide, carbon monoxide and hydrochloric acid. A small amount of nitric oxide was produced firom the reaction of air in the microwave-induced plasma.Item Oxidative destruction of organic contaminants utilizing ultrasound(Texas Tech University, 1996-08) Fahrenkrog-Hallman, Erin ElizabethMankind, over the many years of the industrial age, has made and utilized many useful chemicals. Not all of these chemicals are benign, and it becomes a particular problem when they come in contact with the environment. Whether or not the introduction of these chemicals into the environment was deliberate, mankind has a duty to address and solve these contamination problems.Item Sorption studies of subsurface pantex soils(Texas Tech University, 1997-08) Givens, Dennis R.The Pantex Plant is a Department of Energy facility that is jointly managed by Mason and Hanger-Silas Mason Company, Inc., and Battelle Memorial Institute (BMI). It is located approximately 18 miles northeast of Amarillo, Texas. The plant was built by the U.S. Army in 1942 for the purpose of ordnance production. The current primary mission deals with the assembly, disassembly, maintenance and modification of the nation's nuclear weapons. The plant also performs on-site machining and casting of conventional high explosives for use in nuclear weapons. Contamination of the groundwater beneath the Pantex Plant by several contaminants has been detected. Primary contaminants that have been detected are chromium, trinitrotoluene (TNT), trichloroethylene (TCE), high mehing explosive (HMX), and research and development explosive (RDX). The contamination has thus far been restricted to a perched aquifer that underlies the plant. However, there is concern that these contaminants could reach the Ogallala aquifer below if not naturally attenuated by the perched aquifer.