Remediation of Lead and Cadmium Contaminated Soil Using Lime with Nanosolicamaterials

Abstract

Soil contamination by heavy metals significantly damages the environment, human health, plants, and animals, which has become a burning issue recently. The presence of contaminated soils due to industrials and mining activities is a major concern in today’s heavily industrialized world. With the rapid development of society, more and more soils are polluted by heavy metals, which leads to a change in soil engineering properties. Several types of technology have long been in use to remedy the heavy metal-contaminated soil. Among them, solidification and stabilization have been widely adopted. In engineering practice, engineers usually use additives to solidify and stabilize (s/s) heavy metal-contaminated soils. Solidification and Stabilization is an economic and effective technology in the remediation of contaminated soil by heavy metals, as well as sludge and sediment. The main purpose of the study was to investigate the effect of (nanomaterial materials) on the remediation of contaminated soil by the (S/S) technique. The soil was polluted with (2000 mg/kg and 1000 mg/kg) of Lead and Cadmium respectively by using Lead and Cadmium nitrates. The Pb and Cd- impacted soil was remediation using rich silicon materials of (nano-silica ) as an alternative cementitious material, and replaced with contaminated soil at (3, 5, and 7%) respectively with (5% and 10%) Lime. Nanosilica was prepared from plant extracts. The binder performance was analyzed by using unconfined compressive strength ( UCS) on the solidified soil at three curing times which were 7, 14, and 28 days. TCLP was also applied to investigate the treatment degree of solidified soil for the specimens within 28 days. The result of (UCS) indicated development in strength with curing day for all binders and proved that all mix ratios exceed the minimum Criteria of landfill disposal which is 340 kPa (0.34 N/mm2). It also showed increases in strength with using nano-silica with a lime binder. The result of the leaching test for the stabilized soil after 28 days of curing, showed a reduction in lead and cadmium leaching rate for all binders, below the EPA lead leachability limit of 5 mg/l and cadmium 1 mg/l. The results showed that the sample SH2N5L10 after 28 days is the best percentage for decreasing the leaching rate of lead and cadmium, as it reached (1.4 mg /l and 0.012 mg/l) respectively with the highest compressive strength of 4852 Kpa.