Environmental reclamation through use of colloid foam flotation, in-situ soil aeration and in-situ surfactant flushing

Five laboratory scale heavy metal removal techniques were tested for their ability to remove Sb(III) from aqueous solution. Residual Sb(III) concentrations {dollar}<{dollar}1 ppm were obtained by coprecipitation of Sb(III)/Fe(III) hydroxides, adsorptive colloid flotation of Sb(III)/Fe(III) hydroxide coprecipitates with sodium dodecylsulfate, and coprecipitation with CaO (lime). These methods appear to be acceptable industrial techniques. Removal of Sb(III) by coprecipitation as Sb(III)/Al(III) hydroxides, and coprecipitation as Sb{dollar}sb2{dollar}S{dollar}sb3{dollar} were ineffective methods.; In an effort to optimize the economics associated with adsorbing colloid flotation of Pb(II), Cd(II), and Cu(II), each of the n-alcohols in the homologous series from methanol to n-octanol was tested for its ability to act as a cosurfactant with the anionic surfactant, sodium dodecylphosphate (SDP). N-hexanol behaved most satisfactorily as a cosurfactant, with a 3:1 ratio of n-hexanol to SDP yielding optimal results.; Conductivity titration revealed that the mono-anionic form of SDP is insoluble in H{dollar}sb2{dollar}O and that SDP forms micelles only at pH values below approximately 5 (the pH of the first equivalence point).; A previously unpublished Henry's Law mathematical model for soil vapor stripping is discussed and refined. The model and its refinement both predict the change in volatile organic concentration in contaminated soil as a function of position and time. The 2-point finite difference formula used to represent the advection term in the continuity equation was replaced with a 4-point asymmetrical formula which had been shown to suffer to a lesser degree from numerical dispersion. Model comparisons showed that the effect of dispersion was in fact negligible in the first model, due to the comparatively low gas flowrates typical of soil aeration. In other comparisons the effect of gas flowrates, vent pipe depths, and Henry's Law constants on final results were observed.; The solubility of three prototype hydrophobic organic compounds (naphthalene, biphenyl, p-dichlorobenzene) in aqueous surfactant solutions was tested as a function of surfactant (sodium dodecylsulfate) concentration. A gentle extraction technique for recovering used surfactant solution for recycle was developed and tested. The ability of sodium dodecylsulfate to remove hydrophobic compounds from soil was studied. The type of soil makes little difference in the rate of contaminant removal, but high clay content restricts surfactant flow and consequently decreases contaminant removal. Surfactant flushing may well be an attractive soil remediation technique in certain site specific cases.