Uranium enrichment by the separation-nozzle process

The Science of Nature - The development of reliable manufacturing methods for commercial separation elements, the successful operation of separative stages, and extensive tests performed on plant...     

Simulating a thermal water quality trading market for education and model development

Thermal water quality trading is an emerging policy tool that allows thermal polluters to comply with effluent restrictions by paying landowners to plant shade trees. A simulation game was created to help participants understand the structure, dynamics, benefits, and drawbacks of thermal water quality trading markets. Simulation participants negotiate to make trades, and their decisions are entered into a system dynamics model that simulates tree growth and water temperature. A debriefing session allows the participants to discuss outcomes and strategies. The exercise has been performed twice and has proven to be a useful teaching tool. These simulations provided valuable insight into decision-making strategies in thermal water quality trading markets, suggesting decision rules that the researchers used for subsequent model development.     

Removal of TNT and RDX from water and soil using iron metal

Contaminated water and soil at active or abandoned munitions plants is a serious problem since these compounds pose risks to human health and can be toxic to aquatic and terrestrial life. Our objective was to determine if zero-valent iron (Fe(0)) could be used to promote remediation of water and soil contaminated with 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). As little as 1% Fe(0) (w/v) removed 70 mg TNT litre(-1) from aqueous solution within 8 h and removed 32 mg RDX litre(-1) within 96 h. Treating slurries (1:5 soil:water) of highly contaminated soil (5200 mg TNT and 6400 mg RDX kg(-1) soil) from the former Nebraska Ordnance Plant (NOP) with 10% Fe(0) (w/w soil) reduced CH(3)CN-extractable TNT and RDX concentrations below USEPA remediation goals (17.2 mg TNT and 5.8 mg RDX kg(-1)). Sequential treatment of a TNT-contaminated solution (70 mg TNT litre(-1) spiked with (14)C-TNT) with Fe(0) (5% w/v) followed by H(2)O(2) (1% v/v) completely destroyed TNT and removed about 94% of the (14)C from solution, 48% of which was mineralized to (14)CO(2) within 8 h. Fe(0)-treated TNT also was more susceptible to biological mineralization. Our observations indicate that Fe(0) alone, Fe(0) followed by H(2)O(2), or Fe(0) in combination with biotic treatment can be used for effective remediation of munitions-contaminated water and soil.