A comparison study on heavy metal/metalloid stabilization in Maozhou River sediment by five types of amendments

Abstract

Purpose River sediment pollution by heavy metals/metalloids has attracted widespread attention due to a serious threat to the ecosystem and human health. As an effective and economical alternative, the stabilization method was considered by previous studies for the remediation of sediments polluted by metals/metalloids. However, a comprehensive study is required for an extensive comparison on the effects of metal/metalloid immobilization based on the application of different materials as sediment amendments. Materials and methods In this study, the Maozhou River was selected as the study area, and the stabilization method was applied for the remediation of the river sediment polluted by metals and metalloids. Five materials (CaCO 3 , Ca(OH) 2 , zeolite, kaolin, FeCl 2) were selected as amendments for the metal/metalloid stabilization in the collected sediment. A modified BCR procedure was employed for the speciation analysis of heavy metals and metalloid in the sediment before and after remediation. A TCLP (toxicity characteristic leaching procedure) investigation was performed to further evaluate the immobilization of heavy metals in acidic environment. Results and discussion The sediment of the Maozhou River was heavily polluted by heavy metals and metalloid. The speciation of As, Pb, Cr, and Mn mainly exists as residual fraction (F4), while that of Ni, Cu, and Zn was identified as exchangeable metal and carbonate-associated fraction (F1) and fraction associated with Fe-Mn oxides (F2). Moreover, the F2 fraction of Co was observed as the major speciation. Through the application of five materials (CaCO 3 , Ca(OH) 2 , zeolite, kaolin, FeCl 2) as sediment amendments, the metal/metalloid speciation was transferred into F4. When five amendments were compared, the stabilization effect can be ordered as CaCO 3 > zeolite > FeCl 2 > kaolin > Ca(OH) 2 based on the modified BCR results. TCLP results showed that using Ca(OH) 2 and CaCO 3 as amendments can significantly reduce the metal leachability in an acidic environment, while zeolite is effective for most of the heavy metals and metalloid. Conclusions The results showed that the sediment of the Maozhou River was seriously polluted by a variety of heavy metals and metalloids. This study provided extensive information on the speciation of metals or metalloid and the effect of various amendments on metals and metalloid stabilization, which can be of vital importance for further remediation of metal/metalloid-polluted sediment.

Characterization and Analysis of the Carbonation Process of a Lime Mortar Obtained from Phosphogypsum Waste

“…This process not only allows the reuse of PG, but also helps to mitigate the increasing concentration of CO 2 in the atmosphere recycling a hazardous waste [ 7 ].…”

Strength and Leaching Behavior of Contaminated Mining Sludge at High Water Content Stabilized with Lime Activated GGBS

“…Solidification/stabilization is one of the most applied technology to improve sludge stability [ 4 ] and is a very recognized technique for the treatment of heavy metal contaminated soils [ 5 ]. After mixing the binder with the sludge, the binders react with heavy metal salts and form precipitations (i.e., compounds or insoluble complex hydroxides) due to their alkaline nature [ 6 ]. Furthermore, the heavy metals are encapsulated by hydration products such as calcium silicate hydrate (CSH), calcium aluminate hydrate (CAH) generated during the hydration process [ 7 ].…”

Immobilization of Heavy Metals in Contaminated Soils—Performance Assessment in Conditions Similar to a Real Scenario

“…The traditional method used to remediate HM-contaminated soils consists in excavation and relocation to a landfill. The high costs, limited landfills availability [9], and possibility of hazardous exposure of this traditional remediation method, led to the development of new methods that are more cost-effective and less harmful to the environment, like the solidification/stabilization (S/S) of soil [10]. S/S consists of mixing additives with the soil with the objective to reduce the potential migration of HM and thus the risk of contaminating adjacent areas.…”

“…This technique has been supported by various associations due to its potentialities [11][12][13][14]. Some of the mixing additives used in the S/S technique are binders, clay minerals, alkaline materials, organic compounds, and more recently, nanomaterials [10,[15][16][17][18][19][20][21].…”