Immobilization of Pb Contaminated Soil using Modified Clay

Abstract

Natural clays (i.e., montmorillonite and diatomite) modified by iron and manganese oxide were used as immobilization agents for the remediation of Pb contaminated soil. Batch sorption experiments were conducted to investigate the effect of surface modification on Pb sorption. Pb sorption capacity in modified clays was higher than that in natural clays. Pb sorption capacity in modified and unmodified clays was in the order of Mn-diatomite (1.967 mmol/g) > Mn-montmorillonite (0.718 mmol/g) > Fe-diatomite (0.457 mmol/g) > Fe-montmorillonite (0.330 mmol/g) > montmorillonite (0.233 mmol/g) > diatomite (0.025 mmol/g). Effects of modified clay amendment and ageing (or contact time) on immobilization of Pb were evaluated by a toxicity characteristic leaching procedure (TCLP) and sequential extraction. An artificially polluted natural soil (APNS) with Pb (59.72 mmol Pb/kg soil) was used in immobilization experiment. Lead immobilization efficiency in APNS with modified clay was in the order of Mn-montmorillonite (93%) > Mn-diatomite (86%) > Fe-montmorillonite (81%) > Fe-diatomite (80%). Among the tested modified clays, Mn-montmorillonite was the most efficient in Pb immobilization. Results of sequential extraction of Pb from APNS after immobilization with modified clays indicate that mobile fraction (i.e., exchangeable and carbonate fraction) decreased as contact time increased, while less mobile (i.e., reducible) fraction increased from 27% to 60% of the total amount extracted. This indicates that addition of modified clay to APNS transforms Pb in mobile fraction into reducible fraction.

Sequential Analysis of Metals in Municipal Dumpsite Composts of Kano Metropolis, Nigeria

“…The composts around the dumpsites are therefore subjected to different types of pollution including those caused by heavy elements. Metals such as cadmium, mercury and arsenic are the most hazardous (Park and Shin, 2006). The risks associated with the presence of heavy metals are varied and depend on their chemical forms (metal, oxide, salt and organometallic) (Kashem et al, 2007).…”

Assessment of biological augmentation technology of hazardous pollutants existing in drainage water in Bahr El-Baqar drain, Egypt

“…Likewise, the results, oil and grease decreased from 13 mg/L to 9.5, 8.2 and 7.2 mg/L after 6, 12 and 24 h contact times respectively (Table 2). In this study, fecal coliform and E. coli counts in Bahr El-Baqar were 4.6x10 3 and 1.6x10 3 MPN-index/100mL and reached to 2.8x10 3 and 1.1x10 3 MPN-index/100mLafter 6 h contact time of biological treatment. Only one log reduction was observed after 12 and 24 h contact times (Table 2).…”

“…In case of (run 3), the obtained results cleared that the physicochemical and bioindicatorfeatures of tested water and after biological treatment were presented in Table (3). The pH, TSS, TDS, COD, and BOD of drainage water were 7.6, 124 mg/L, 2410 mg/L, 118 mg O 2 /L and 43 mgO 2 /L, respectively.…”

“…The discharge of industrial, agricultural and municipal wastewaters in Bahr El Baqar drain which farmer uses it in irrigation led to contamination of environment. These soils receive many kinds of pollutants, especially heavy metals such as lead, cadmium, nickel, and mercury, which are considered the most hazardous [ 3]. However, the question still not answers yet is ''what is the environmental and ecological risk assessment of heavy metals of Bahr El Baqar on sustainable soil resources''?…”