Biotechnology for Zero Waste – Emerging Waste Management Techniques (Chaudhery Mustansar Hussain (editor) etc.)

Bioremediation of Heavy Metals

Tanmoy Paul¹and Nimai C. Saha²

1DNC College, Department of Zoology, Murshidabad, West Bengal 742201, India

2The University of Burdwan, Fishery and Ecotoxicology Research Laboratory (Vice-Chancellor’s Research

Group), Department of Zoology, Burdwan, West Bengal, 713104, India

5.1

Introduction

Human habitable ecosystems are rich in heavy metals since ancient time; it is the

effect of spontaneous geogenic and modern-day anthropogenic activities, which are

responsible for contemporary environmental heavy metal contamination [1]. Heavy

metals could also be derived from both direct sources such as sludge dumping, indus-

trial effluents, and mine trailing and indirectly through highway runoffs, which in

turn lead toward the exploration of metal–microbe interactions that could recover or

stabilize heavy metals in soils and effluents. In recent times, the heavy metal contam-

ination caused biomagnifications that ultimately resulted in a major human health

hazard globally.

Essential heavy metals, for instance, iron, zinc, and copper, are required by liv-

ing organisms in trace amounts, but their presence above a threshold concentration

often observed to be toxic. Among the heavy metals, cadmium (Cd), chromium (Cr),

and arsenic (As) are reported to act as a carcinogen as designated by the Interna-

tional Agency for Research on Cancer (IARC) and the US Environmental Protection

Agency (USEPA) [2]. It has also been observed that various metals such as iron (Fe),

zinc (Zn), nickel (Ni), and copper (Cu) are considered essential metals for growth

and other functions, if their level remains within the threshold level [3].

There are an array of techniques, for instance, filtration, chemical precipitation,

reverse osmosis, membrane technology, oxidation and reduction, ion exchange, and

electrochemical treatment, for the removal of heavy metals from a contaminated

environment. However, these techniques have some serious demerits associated

with them. The most important one is their inability to remove heavy metals

found at lower concentration (≤100 mg/l) [4]. These traditional techniques are

expensive and require energy sources and still often alter the properties of soil

without complete removal of metal contaminants. Furthermore, the pollutant may

also be displaced to other sites in the environment where they can accumulate and

may cause the same issue. The presence of an array of traditional decontamination

Biotechnology for Zero Waste: Emerging Waste Management Techniques, First Edition.

Edited by Chaudhery Mustansar Hussain and Ravi Kumar Kadeppagari.