| The effectiveness and limitations of bioremediation and solidification/stabilization (S/S) to treat naphthalene and chromium wastes were investigated. This represents the wastes from steel production, chrome plating, leather tanning, wood treatment, coal, lubricants, motor fuels and oil refinery industries.; The extraction of contaminants from contaminated soils and the sorption of contaminants onto the soil constituents have been quantified. Solutions of 0.28 M Na2CO3/0.5 N NaOH (96°C) and methanol (100%) extracted more than 90% of Cr(VI) and naphthalene from contaminated soils. The Freundlich isotherm represented the sorption of contaminants to the soil constituents. The reduction of Cr(VI) and the oxidation of Cr(III) in the chromium cycle have been verified in soil environment.; Naphthalene-oxidizing microorganisms were isolated from field samples. Acclimated Flavobacterium sp. was used in bioremediation studies. Factors such as metal toxicity, contamination level, and soil characteristics were investigated in continuously stirred batch bioreactors. Naphthalene (30 mg/L) was biodegraded to below 5 mg/L within 60 hours of operation depended on the Cr(VI) concentration. The biodegradation process was inhibited when 500 mg/L of K2CrO4 was added. Models were developed based on the biodegradation kinetics to quantify the metal inhibition effect. A three-phase model was also developed to simulate the biodegradation of naphthalene in slurry bioreactor and to understand the role of dissolution and desorption.; Type I Portland cement was used as a binder to treat naphthalene and chromium wastes. Factors such as contamination level, cement-to-soil ratio, site characteristics, and potential additives were investigated. A combination of FeCl2 reduction and S/S was effective to treat Cr(VI)-contaminated soil. X-ray diffraction was used to identify the reaction products. Simple relationships have been developed to predict the leaching of contaminants during the modified TCLP test. |
