An innovative stabilization/solidification treatment For contaminated soil remediation: demonstration project results

Abstract

Background, aim, and scope An innovative stabilization/ solidification (S/S) process using high-performance additivated concrete technology was developed for remediating soil contaminated by metals from abandoned industrial sites. In order to verify the effectiveness of this new ex situ S/S procedure, an area highly contaminated by metallic pollutants (As, Cd, Hg, and Pb), due to the uncontrolled discharge of waste generated from artistic glass production on the island of Murano (Venice, Italy), was selected as a case study. The technique transforms the contaminated soil into an aggregate material suitable for reuse as on-site backfill. This paper reports the main results of the demonstration project performed in collaboration with the local environmental protection agency (ARPAV). Materials and methods An ex situ treatment for brownfield remediation, based on the transformation of contaminated soil into very dense, low porous, and mechanically resistant granular material, was set up and tested. Specific additives (water reducers and superplasticizers) to improve the stabilized material properties were developed and patented. A demonstration plant assembled on the study area to treat 6 m 3 h -1 was then tested. After excavation, the contaminated soil was screened to remove coarse material. The fraction Ø >4 mm (coarse fraction), mainly composed of glass, brick, concrete, and stone debris, was directly reused on site after passing through a washing treatment section. The highly polluted fraction Ø≤4 mm (fine fraction) was treated in the S/S treatment division of the plant (European patent WO/ 2006/097272). The fine fraction was mixed with Portland cement and additives defined on the basis of the high performance concrete technique. The mixture was then granulated in a rolling-plate system. After 28 days curing in an onsite storage area to allow for cement hydration, the stabilized material was monitored before its in situ relocation. The chemical, mechanical, and ecotoxicological reliability and performance of the treatment was checked. Metal leachability was verified according to four leaching test methods: Italian Environmental Ministry Decree (1998), EN 12457 (2002) tout court, amended only with MgSO 4 and, lastly, with artificial sea water. The mechanical properties were measured according to BS (1990) and AASHTO (1999) to obtain the Aggregate Crushing Value

Sequential solidification/stabilization and thermal process under vacuum for the treatment of mercury in sediments

“…The first step of the process is based on the production of the cementitious granular material (Scanferla et al 2009). The lab-scale granular production was developed as follows (Bonomo et al 2009): (1) 2 min dry mixing (by a mechanical mixer Eirich R02) of the sediment and Portland cement;…”

“…This is done to overcome the problems mentioned above, occurring when treating fine-grained materials with thermal desorption. With reference to soils contaminated by heavy metals, the first part of the process has been already described in Scanferla et al (2009). In the present paper, the whole treatment remedial capability is assessed on marine sediments, focusing on the effects of thermal desorption on mercury concentration, leachability and speciation.…”

Efficiency modeling of solidification/stabilization of multi-metal contaminated industrial soil using cement and additives

“…The use of various cement chemical admixtures, such as retarders, accelerators and plasticizers, have a long tradition in civil engineering for obtaining certain special properties of cementitious products [8]. Similarly, Scanferla et al [9] used ordinary Portland cement amended with water reducers and superplasticizers for the S/S of As, Cd, Hg, and Pb contaminated soil on the island of Murano (Venice, Italy). The S/S mixture was granulated in a rolling-plate system.…”

Ex-Situ Remediation Technologies for Environmental Pollutants: A Critical Perspective

“…Chen et al ( 2009b ) reported 100 % immobilization of heavy metals by the application of enhanced carbonation coupled with CO 2 and Na 2 CO 3 in cement-based S/S of heavy metal-bearing sediment. Scanferla et al ( 2009 ) developed and patented an innovative S/S technology using high performance additive (water reducers and superplasticizers) concrete technology and observed superior leaching of heavy metals (99 %) at fi eld-scale. Leonard and Stegemann ( 2010 ) reported more than 90 % immobilization of hydrocarbons in petroleum drill cuttings using Portland cement along with the addition of high carbon power plant fl y ash which act as a novel sorbent for organic pollutants.…”