Agriculture Reference
In-Depth Information
5
Multi-Technique Application for Waste Material
Detection and Soil Remediation Strategies:
The Red Mud Dust and Fly Ash Case Studies
Claudia Belviso, Simone Pascucci, Francesco Cavalcante, Angelo Palombo,
Stefano Pignatti, Tiziana Simoniello and Saverio Fiore
Istituto di Metodologie per l'Analisi Ambientale, CNR,
C/da J. Loja - Tito Scalo (PZ)
Italy
1. Introduction
Increasing amounts of residues and waste materials coming from different industrial
activities have become a serious problem for the future. However, over the last few years
there has been a growing emphasis on the utilization of these materials in several
remediation technologies in order to clean up contaminated soil.
Among them, two examples of industrial residues are fly ash and red mud.
Fly ash is a by-product of thermal power plants partly used in concrete and cement
manufacturing. More than half of it is disposed of in landfills because it finds no other
application. It is composed of minerals such as quartz, mullite, subordinately hematite and
magnetite, carbon, and a prevalent phase of amorphous aluminosilicate.
Red mud is a waste material formed during the production of alumina when the bauxite ore
is subject to caustic leaching. It is mainly characterized by the presence of hematite, goethite,
gibbsite, rutile and sodium as sodium aluminum silicates or hydro-silicates. A wide variety
of organic compounds could also be found (e.g. polybasic and polyhydroxy acids, humic
and fulvic acids, carbohydrates, acetic and oxalic acids, furans).
The mineralogical and chemical characterization of these two waste materials is generally
carried out by X-ray powder diffraction, thermal analysis, infrared spectroscopy, scanning
electron microscopy and chemical methods. Imaging spectroscopy under controlled
conditions in laboratory is also applied.
Many research activities on the neutralization of fly ash and red mud materials as well as to
solve the problems connected to their disposal are developed in the last few years. Some of
these focus on their utilization in different remediation technologies to immobilize toxic
elements. They are in fact used in solidification/stabilization technologies for soil
remediation treatment and some studies are based on the immobilization of toxic elements
in synthetic zeolites crystallized by treated fly ash.
The chapter investigates these two industrial residues focusing both on their chemical-
mineralogical properties and their characterization as toxic materials. Studies of remediation
methods to reduce the environmental risks due to polluting metals by using red mud and
fly ash are presented as well as examples of landfill monitoring and airborne hyperspectral
