Page 241 - Materials Chemistry, Second Edition

222 Life Cycle Assessment of Wastewater Treatment

11.1 INTRODUCTION
Heavy metal contamination is an issue related to regions of intensified industry. Heavy
metal–polluted groundwater is a genuine worry in most nations (Naushad et al., 2017;
Ahamad et al., 2017). Environmental restoration of contaminated groundwater in
the modern agricultural and urban domains is an extraordinary challenge in recent
decades because of anthropogenic activities (Mahar et al., 2015). Anthropogenic
activities, for example, mining, purifying operations, and farming, have unobtru-
sively increased the levels of heavy metals, for example, Cd, Co, Cr, Pb, Cu, Zn, As,
and Ni, in soil up to hazardous levels (Sharma et al., 2014).
Heavy metals constitute an exceptionally heterogeneous group of components,
widely varying in their compound properties and organic capacities. Heavy metals
are classified as natural poisons because of their toxic effects on plants, animals, and
people (Sharma et al., 2017). Heavy metal contamination of soil results from anthro-
pogenic and also natural activities. Heavy metals are persistent in nature and hence,
become aggregated in soils and plants. Dietary intake of numerous metals at high
levels through the consumption of plants has long-term deleterious effects on human
health. The effect of heavy metals on aquatic organisms is due to the development of
contamination from different diffuse or point sources, which frequently combine in
unforeseen ways in the ecosystem. In this way, they represent a hazard to maritime
fauna, especially to fish, which constitute one of the genuine sources of protein-rich
food for mankind.
Groundwater contamination, frequently because of contaminant leakage from
transfer locales, is a major issue. Nonetheless, street routes, refuse disposal sites, and
cars are now thought to be among the biggest sources of heavy metals. Numerous
industrial activities from which chemicals or wastes might be discharged to the earth,
either purposefully or accidentally, can possibly contaminate ground water. Industries
such as plating, earthenware production, glass, mining, and battery assembly are
viewed as the primary sources of excess metals in neighborhood water streams, which
will result in the contamination of groundwater with heavy metals. Furthermore,
heavy metals that are normally found in high concentration in landfill leachate are
likewise a potential source of contamination for groundwater (Aziz et al., 2004).
The raised level of heavy metals in the groundwater represents a considerable
hazard to users of nearby resources and possibly to the common habitat. At the point
when groundwater winds up clearly polluted by contaminants, it causes illness, and
enormous trouble is required to clean it. The World Health Organization (WHO)
has already understood this issue and begun issuing standards for safe groundwater.

11.2 HEAVY METALS: SOURCES AND EFFECT
IN THE ENVIRONMENT

Toxic metals, to a huge degree, are widespread in the earth due to industrial efflu-
ents, natural wastes, dumping of consumables, and the transport and power era. The
sources of heavy metals in the environment are shown in Figure 11.1. They can be
dispersed to places many miles from their sources by the wind, dependent on whether
they are in airborne or particulate form. Metallic contamination is eventually washed