Page 248 - Materials Chemistry, Second Edition

Technologies for Treatment of Heavy Metal–Contaminated Groundwater 229

• They displace essential nutritional minerals from their specific sites, thereby
impeding their functions within the body. It is, in any case, difficult to live
in a domain free of heavy metals. There are numerous routes by which
these toxins can be introduced into the body: for example, in food, in drink,
through the skin, and through breathing the air.

By and large, the harmfulness of metal particles to humans is because of the
reactivity of these particles with the cell’s basic proteins and compounds and
tissue systems. The organs subject to particular metal toxicities are typically
those organs that accumulate the most noteworthy levels of the metal in vivo.
This is generally dependent on the course of introduction and the properties of
the metal compound, that is, its valency state, instability, lipid solubility, and
so forth.

11.4 STEPS FOR ANALYZING HEAVY METALS
IN WASTEWATER SAMPLES
Wastewater for testing may contain particulates or natural materials, which may
require pre-treatment before spectrometric investigation. To break down the aggre-
gate metal substance of a specimen, it is necessary to categorize metals as inorgani-
cally and naturally bound, dispersed, or particulate. Generally, different steps must
be followed for metal analysis; each step is critical and a potential source of error if
not performed in the correct sequence. Figure 11.3 shows the steps needed to analyze
the heavy metals in wastewater.
After choosing an applicable sample preparation step, the most helpful methods
are clarified underneath, such as atomic absorption spectrometry (AAS), induc-
tively coupled plasma optical emission spectrometry (ICP-OES), inductively cou-
pled plasma mass spectrometry (ICP-MS), laser initiated breakdown spectroscopy
(LIBS), and anodic stripping.

11.5 TREATMENT METHODOLOGIES

Cadmium, zinc, copper, nickel, lead, mercury, and chromium are regularly detected
in industrial wastewaters. They originate from metal plating, mining activities, puri-
fying, battery manufacturing, tanneries, oil refining, paint fabrication, pesticides,
pigment manufacture, printing and photographic enterprises, and so on. The lethal
metals, presumably existing in high concentrations (even up to 500 mg/L), must
be adequately treated/expelled from the wastewater. In the unlikely event that the
wastewater is released straight into the receiving waters, it will constitute an awe-
some hazard for the aquatic environment, while immediate release into the sewer-
age system may adversely influence the ensuing natural wastewater treatment (Wan
Ngah and Hanafiah, 2008).
Some advances have been made in the remediation of heavy metal–contami-
nated groundwater, and the results are indisputable. Figure 11.4 illustrates the clear
outcome from the remediation process (treatment of heavy metal–contaminated
groundwater).