An Integrated Method Incorporating Sulfur-Oxidizing Bacteria and Electrokinetics To Enhance Removal of Copper from Contaminated Soil

Abstract

The combination of bioleaching and electrokinetics for the remediation of metal contaminated land has been investigated. In bioleaching, bacteria convert reduced sulfur compounds to sulfuric acid, acidifying soil and mobilizing metal ions. In electrokinetics, DC current acidifies soil, and mobilized metals are transported to the cathode by electromigration. When bioleaching was applied to silt soil artificially contaminated with seven metals and amended with sulfur, bacterial activity was partially inhibited and limited acidification occurred. Electrokinetic treatment of silt soil contaminated solely with 1000 mg/kg copper nitrate showed 89% removal of copper from the soil within 15 days. To combine bioleaching and electrokinetics sequentially, preliminary partial acidification was performed by amending copper-contaminated soil with sulfur (to 5% w/w) and incubating at constant moisture (30% w/w) and temperature (20 °C) for 90 days. Indigenous sulfur-oxidizing bacteria partially acidified the soil from pH 8.1 to 5.4. This soil was then treated by electrokinetics yielding 86% copper removal in 16 days. In the combined process, electrokinetics stimulated sulfur oxidation, by removing inhibitory factors, yielding a 5.1-fold increase in soil sulfate concentration. Preacidification by sulfur-oxidizing bacteria increased the cost-effectiveness of the electrokinetic treatment by reducing the power requirement by 66%.

Fungal Leaching of Uranium from its Geological Ores in Alloga Area, West Central Sinai, Egypt

“…In contrast to these observation A. niger showed a maximal bioleaching of copper (60%) at a concentration of 5% of the mining residue (Maini et al 2000). These observations refer that the applied ore concentration is crucial and varied with the type of the ore and also with the organisms used in the bioleaching process.…”

“…The biological leaching of uranium was begun during the 1960,s (Fisher, 1966;Fletcher, 1970;Kelly, 1976;Khalid et al, 1993). Much work have been done on the bacterial leaching of metals from low-grade ores using the activity of sulfur-oxidizing bacteria, especially Thiobacillus ferroxidans (Kuznetsov, 1963;Kelly, 1976;Brierley, 1978;Kelly et al, 1979;Norris and Kelly, 1982;Karavaiko, 1985;Ehrlich and Brierley, 1990;Schippers et al, 1995;Gomez Ore samples: Two radioactive geologic samples were collected in and Bosecker, 1999; Maini et al, 2000). Bioleaching of copper, sterile polyethylene bags from Alloga region in the west central uranium and gold ores occurred direct, when microbes change a Sinai, Egypt.…”

Electrokinetic Copper and Iron Migration in Anaerobic Granular Sludge

“…Besides EDTA 4− addition (Table IV), this could be also achieved by variations in temperature (Mohammadi et al, 2005), as increasing temperatures may increase the transport rate of heavy metals towards the appropriate electrodes. Alternatively, the pH of the sludge cake could be reduced and, therefore solubilization of contaminants could be achieved, by the addition of sulfur-oxidizing bacteria and subsequent aeration of the sludge cake, as these bacteria produce sulfuric acid from the reduced sulfur compounds present in anaerobic sludge (Maini et al, 2000).…”

Enhanced biotransformations and product recovery in a membrane bioreactor through application of a direct electric current

“…For example, pulsed high voltages are used within a number of industries to sterilize solutions (Wouters and Smelt, 1997), but they can also be used to permeabilize cells in order to introduce foreign genetic material (Gehl, 2003). Low-voltage direct electric currents can be applied to bacterial cultures, provided that these are protected from direct contact with the electrodes through the presence of a matrix or membranes (Jackman et al, 1999) and they have also been applied to soils to remove inhibitory contaminants, leading to enhanced microbial activity (Maini et al, 2000). A similar effect has been observed with Escherichia coli immobilized in hydrogels in which the electrokinetic removal of organic acids from glucose fermentation enhanced further glucose catabolism (Chang et al, 1995).…”