Environmental Engineering Reference
In-Depth Information
CHAPTER 9
Iron-Based Magnetic Nanoparticles for Removal of
Wastewater
Irene M. C. Lo, Jing Hu, and Guohua Chen
9. 1
Introduction
The presence of heavy metals in wastewater and surface water becomes a severe
environmental and public health problem. In particular, copper, nickel and chromium
found in wastewaters are designated as priority pollutants by the USEPA (EPA, 1990).
The vast majority of toxic metals are waste products of industrial and metallurgical
processes, especially the effluents from electroplating plants, metal finishing and
extractive metallurgy processes which contain high concentrations of dissolved metals
(Ayuso et al., 2003). Facing the rapidly changing environmental legislation, market
perception, and public awareness, industries are challenged to adopt an effective,
environmentally sound technology to remove heavy metals (Aggarwal et al., 1999). The
metal concentrations must be reduced to meet the legislative standards, and recovered
where feasible (Wang et al., 2003). Thus, advanced and innovative methods of
wastewater treatment are continuously being developed to deal with waste metals.
A variety of methods have been applied for removal of chromium, copper, and
nickel from water and wastewater. Commonly used treatment methods include pH
adjustment and lime precipitation, coagulation and coprecipitation into metal hydroxide,
sulfide treatment, adsorption onto activated carbon and alumina, ion exchange, and
reverse osmosis (Ouki and Neufeld, 1997; Blais et al., 2003). Although the effectiveness
of these processes has been widely proved, they all process some inconveniences and
limitations due to high energy requirements, complex operation, incomplete metal
removal, and a large amount of sludge production (Xu et al., 2002). Furthermore,
increasingly stringent environmental regulations pertaining to discharges containing
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