Removal of hexavalent chromium of contaminated soil by coupling electrokinetic remediation and permeable reactive biobarriers

PURPOSE: In this study, a novel and ecological alternative have been developed to treat soils contaminated with hexavalent chromium coupling two well-known systems: electrokinetic remediation and permeable reactive biobarriers. The electric field promotes the electromigration of the hexavalent chromium oxyanions towards the anode. The biobarriers were placed before the anode electrode, in order to promote the reduction and retention of the chromium migrating in its direction. Thus, this technology provided a global treatment to soil removal without subsequent treatments of the contaminated effluents. METHODS: The electrokinetic system was coupled with two different permeable reactive biobarriers composed by Arthrobacter viscosus bacteria, supported either in activated carbon or zeolite. An electric field of 10 V was applied and two different treatment times of 9 and 18 days were tested. RESULTS: Removal values of 60% and 79% were obtained when electrokinetic treatment was coupled with zeolite and activated carbon biobarriers, respectively, for a test period of 18 day. The reduction of hexavalent chromium to trivalent chromium was around 45% for both systems. CONCLUSIONS: In this work, two types of biobarriers were efficiently coupled to electrokinetic treatment to decontaminate soil with Cr(VI). Furthermore, the viability of the new coupling technology developed (electrokinetic + biobarriers) to treat low-permeability polluted soils was demonstrated.This work was supported by the Spanish Ministry of Science and Innovation (CTQ2008-03059/PPQ), Xunta de Galicia (08MDS034314PR). The authors are grateful to the Spanish Ministry of Science and Innovation for providing financial support for Marta Pazos under the Ramon y Cajal program and the Fundacao para a Ciencia e Tecnologia, Ministerio da Ciencia e Tecnologia, Portugal through the PhD grant of Bruna Fonseca (SFRH/BD/27780/2006)

Effect of oral administration of folate sources on plasma folate levels in pigs: Comparison between reduced and oxidized forms of folate

Two experiments were conducted to evaluate the response of plasma folate levels after oral administration of oxidized or reduced forms of folates, using seven Göttingen minipigs. Plasma folate levels, tetrahydrofolate (THF) and 5-methyltetrahydrofolate (5CH3-THF), were determined by high-performance liquid chromatography with electrochemical detection. In exp. 1, the absorption of the oxidized form of folate [(synthetic folic acid(FA)] and the reduced forms of folate (5-formyltetrahydrofolate (5HCO-THF), liver powder and digested bacterial cell powder (DBCP) were evaluated by measuring changes in plasma folate levels after a single oral administration. Liver powder and DBCP contained much reduced forms of folate. The administration of the reduced form of folates increased plasma THF levels while the levels of plasma THF and 5CH3-THF decreased after FA administration. In exp. 2, plasma folate levels were measured after long-term oral administration of FA for 30 d. Immediately after the beginning of the administration, the levels of both THF and 5CH3-THF decreased significantly and remained at a low level during the 30-d administration. Supplementation of sow feed with FA has been recommended in many countries improving reproductive performance. The present study, however, suggests that the oral administration of an oxidized form of folate, FA, may not be as effective as previously thought, and the reduced forms of folate might be preferable for the supplementation of pig feeds. Key words: Folate (reduced), folic acid, pig, oral administration, bacterial cell wall, absorption </jats:p