In situ remediation of metal(loid)-contaminated lake sediments with alkali-activated blast furnace slag granule amendment: A field experiment

Abstract

Purpose Adsorbent amendment to contaminated sediments is one in situ remediation method to decrease the bioaccessibility of pollutants from the sediments. In this work, alkali-activated blast furnace slag (BFS) granules were used in a field experiment at Lake Kivijärvi (Finland). The lake was heavily affected by a mining accident in 2012, which released a significant peak load of metals and sulfate. The purpose of this work was to evaluate the performance of the novel amendment material for in situ remediation in real conditions with a preliminary cost estimation. Methods Alkali-activated BFS granules were prepared and characterized for composition, microstructure, and surface properties. Two mesocosms were placed in the lake: one with granule dosing and another without. Sediment and pore water samples were collected after a two-week period. Similar small-scale experiment was performed in laboratory with a three-month duration. Bioaccessibility of metals from sediments was assessed with a three-stage leaching procedure. Results The granules were effective in decreasing the mobility of Fe, Zn, Ni, and Cr in all leaching stages by approximately 50–90% in comparison with unamended sediment in the mesocosm experiment. Laboratory-scale incubation experiments also indicated decreased release of Ba, Co, Ni, Al, Fe, Mg, Mn and S. The estimated material costs were lower than the removal of the contaminated sediments with dredging and off-site treatment. Conclusion The results showed preliminarily the effectiveness of alkaline-activated BFS in the remediation of metal-contaminated sediments in a field experiment. However, topics requiring further study are the leaching of trace elements from the material and impact on the sediment pH.

Why geopolymers and alkali‐activated materials are key components of a sustainable world: A perspective contribution

“…Since then, geopolymers and AAMs have been studied for example for the adsorption of various toxic metal(loid)s, nutrients, organic dyes, radioisotopes, water hardness, and rare earth elements. 96 Many recent studies aim to simulate realistic (waste)water treatment conditions (e.g., Roviello et al 97 , Gonçalves Nuno et al 98 ), evaluate the regeneration of the adsorbents (e.g., Medri et al 99 ), or report pilot-scale experiments (e.g., Laukkanen et al 100 ). In addition, the development of synergistic composite structures for adsorption with for example graphene oxide, carbon nanotubes, or cellulose nanofibers has become an active research area (see e.g., Selkälä et al 101 , Yan et al 102 , Yan et al 103 ).…”