Disposal of heavy metal‐contaminated sediment from Ulsan Bay, South Korea: treatment processes and legal framework

Abstract

The effectiveness of two different management schemes to dispose of heavy metal-contaminated sediments from Ulsan Bay, South Korea, soil washing and solidification/stabilization, were evaluated through a series of analyses. NaOH proved to be an effective washing reagent for As, extracting 75% of the As in sediment samples. EDTA was found to significantly enhance the extraction of Cu, Pb and Zn. However, complete removal of any metals was not achieved even after application of 100 mM concentrations of washing reagents. Therefore, a solidification/stabilization technique was applied to dredged sediment samples using ordinary Portland cement (1-40%) and fly ash ($20%). Solidified sediments did not release meaningful amount of the metals via leaching tests. Our results suggest that solidification/stabilization is a better option for effective disposal of heavy metal-contaminated sediments than soil washing. A legal framework for the treatment of hazardous wastes and contaminated soils in Korea is discussed.

Source identification of heavy metal contamination using metal association and Pb isotopes in Ulsan Bay sediments, East Sea, Korea

“…Widespread metal pollution in seawater, aerosols, organisms, and sediments in Ulsan Bay on the southeastern coast of Korea has been reported, and the source is believed to be nearby industrial plants, including nonferrous metal and oil refineries, shipbuilding facilities, and a large harbor (Lee et al, 1988;Kang and Lee, 1996;Song, 1996;Yang et al, 1996;Kang et al, 1999;Han and Lee, 2000;Moon et al, 2001;Oh et al, 2010). Although air pollution and wastewater control technologies are in place at some facilities, because this area has experienced various levels of industrial activity over the past 40 years, it is likely to be an important source of metals to the East Sea through coast-offshore transport and atmospheric pathways (Choi et al, 2006(Choi et al, , 2007b.…”

“…Stream sediments (DJ-1, DJ-2) had the same isotopic ratios as S2 and the sediment at 21 cm depth in core P15, which was under this line. Several studies of heavy metal contamination in the seawater, organisms, and sediments of Onsan Bay have been undertaken (Lee et al, 1988;Kang et al, 1999;Han and Lee, 2000;Oh et al, 2010), including studies in which the area of metal contamination was concentrated on this Onsan Bay (Kang et al, 1999). However, most of the contaminated area within Onsan …”

Economical Treatment of Dredged Material to Facilitate Beneficial Use

“…Soil Washing EDTA and Citric Acid Extraction (Oh et al 2011) Oh et al (2011) evaluated soil washing in bench scale testing for treatment of contaminated sediments. EDTA, citric acid (a weak acid that acts as a chelating agent) and NaOH were used as washing agents.…”

“…Solidification and stabilization are probably the most mature technologies of those presented here. EPA defines solidification as "a process that encapsulates waste to form a solid material" (USEPA 1997, as cited in Oh et al 2011); the process reduces the surface area of the solidified materials and coats them with low-permeability materials, thus reducing contaminant mobility (Oh et al 2011). Stabilization is similar to solidification, reducing the leachability of contaminants through the addition of chemical binders.…”

“…Stabilization is similar to solidification, reducing the leachability of contaminants through the addition of chemical binders. "Portland cement and pozzolanic binders, including fly ash and cement kiln dust, are the most popular additives for stabilization/solidification" (LaGrega et al 2000, as cited in Oh et al 2011). Solidification/stabilization (S/S) is typically used to immobilize metals; although S/S may be effective for low levels of organic contaminants.…”