Oyster Shell Powder, Zeolite and Red Mud as Binders for Immobilising Toxic Metals in Fine Granular Contaminated Soils (from Industrial Zones in South Korea).

Cecilia Torres-Quiroz,Janith Dissanayake,Junboum Park

doi:10.3390/ijerph18052530

Cecilia Torres-Quiroz, Janith Dissanayake + Show 1 more

Open Access

https://doi.org/10.3390/ijerph18052530

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Abstract

Low-cost absorbent materials have elicited the attention of researchers as binders for the stabilisation/solidification technique. As, there is a no comprehensive study, the authors of this paper investigated the performance of Oyster shell powder (OS), zeolite (Z), and red mud (RM) in stabilising heavy metals in three types of heavy metal-contaminated soils by using toxicity characteristic leaching procedure (TCLP). Samples were collected from surroundings of an abandoned metal mine site and from military service zone. Furthermore, a Pb-contaminated soil was artificially prepared to evaluate each binder (100× regulatory level for Pb). OS bound approximately 82% of Pb and 78% of Cu in real cases scenario. While Z was highly effective in stabilizing Pb in highly polluted artificial soil (>50% of Pb) at lower dosages than OS and RM, it was not effective in stabilising those metals in the soils obtained from the contaminated sites. RM did not perform consistently stabilising toxic metals in soils from contaminated sites, but it demonstrated a remarkable Pb-immobilisation under dosages over than 5% in the artificial soil. Further, authors observed that OS removal efficiency reached up to 94% after 10 days. The results suggest that OS is the best low-cost adsorbent material to stabilize soils contaminated with toxic metals considered in the study.

Highlights

Soil contaminated with toxic metals is a serious environmental issue worldwide [1,2].Toxic metals exhibit the potential of affecting the soil–food chain, impairing soil fertility [3,4,5] and the quality of drinking water [6]
Soil samples were collected from two sites contaminated with toxic metals, namely, soil from surroundings of an abandoned metal mine site that was classified as silty sand (SM) with a fine content of 22% and soil from a military service area that was classified as well-graded sand (SW) with a fine content lower than 5%
The dosages of oyster shell and zeolite exerted no significant effect on the pH of this soil, whereas red mud dosage had a significant effect on pH

Summary

Introduction

Soil contaminated with toxic metals is a serious environmental issue worldwide [1,2].Toxic metals exhibit the potential of affecting the soil–food chain, impairing soil fertility [3,4,5] and the quality of drinking water [6]. They include surface capping [10], encapsulation [11,12], landfilling, soil flushing [13], soil washing [14,15], electrokinetic extraction [16,17,18], stabilisation/solidification (S/S) [19,20,21], vitrification [22,23], phytoremediation [24,25] and bioremediation Amongst these techniques, S/S has attracted the attention of many researchers due to its low-cost application whilst preserving the long-term stability of the stabilised soil [26,27]. The addition of lime, cement and other cementitious binders to soil has demonstrated excellent performance in treating

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