PubMed · 972061
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E E Volk, R D Partridge. 1976. Decontaminating gloved boxes.. https://pubmed.ncbi.nlm.nih.gov/972061/
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This paper presents the results of a new process of soil decontamination termed as couple electric-hydraulic gradient assisted by ion exchange medium (CEHIXM) in which a hydraulic gradient is coupled with electric gradient in a non-conventional arrangement for the purpose of electrolysis and ion transport. A suitable ion exchange medium was used to capture and subsequently recover the cations. In this process, heavy metals no longer precipitated in the treated soil near the pretreatment zone. The cations were transported out of the soil and captured in the ion exchange medium. Several laboratory tests were conducted to examine the removal of Pb, Cd, Zn and Mn from sandy soils. The experimental results demonstrated the removal efficiencies more than 97% for all the four heavy metals at an energy expenditure of 345 kWh/m(3) of soil.
As part of a Department of Defense project, the US Environmental Protection Agency was responsible for designing, building and field operating a pilot-scale pervaporation unit. The field site was an active dry cleaning facility on the grounds of Marine Corps Base Camp Lejeune in Jacksonville, NC. The overall goal of the project was to remove tetrachloroethylene (PCE) from the soil beneath the dry cleaning shop using a surfactant-based soil remediation fluid and to recycle/reuse the surfactant. In order to reinject the recovered surfactant, the pervaporation unit was required to achieve an average 95% removal of contaminants from the extracted fluid over the duration of the test period. PCE removal averaged 95.8% during peak surfactant levels and exceeded 99.9% in the absence of surfactant, thereby meeting the reinjection requirement. Removal of a group of secondary contaminants at the site, termed Varsol compounds, was monitored via concentrations of three Varsol marker compounds: decane, undecane and 1,3,5-trimethylbenzene. The pervaporation system processed 100,000 gal of groundwater and surfactant solution over a period of 70 days. In order to evaluate and validate process performance, a variety of process variables and properties were monitored over the course of the demonstration. Pervaporation costs are projected to be on the order of $20 per 1000 gal of surfactant solution treated for a moderate size system (10 gpm).
The flow-through leaching test is a test method employed to study the leaching behavior of monolithic stabilized/solidified (S/S) hazardous wastes under the condition that the leachate flows through the sample. This method simulates the leaching process of the S/S hazardous waste disposed under a particular landfill condition when the S/S waste is more permeable than its surrounding materials or when the deterioration of the solidified waste form has reached a state that ground water can flow-through the waste via the porosity system of the S/S waste matrix. This paper describes a study on the long-term performance of the cement-based S/S heavy metal wastes using a flow-through leaching test method. Two series of leaching tests with different synthetic heavy metal waste samples were carried out. The S/S samples were made from five types of heavy metals with two kinds of binders. The metals were Pb(2+), Zn(2+), Cu(2+), Ni(2+) (positive ions as nitrates), and Cr(6+) (a negative ion as potassium dichromate), and the binders were type I ordinary portland cement (OPC) and pulverised fuel ash (PFA). The model developed by Godbee and Joy for simulating the leaching behavior was modified to estimate the diffusivity parameter in this study. The results obtained indicate that since the matrix of the solidified waste in a flow-through leaching tests is always being degraded, the values of diffusivities increase continuously during the leaching period. The diffusivity variation range was from 10(-13) to 10(-3)cm(2)/s, and were normally higher than those obtained from other test methods such as ANS 16.1 test and other dynamic leaching tests.