Chapter 21 - Remediation of heavy metals from wastewater treatment plants using bacteria and algae

Abstract

Pollution of water by heavy metals has become a matter of serious concern. Reclamation of heavy-metal-polluted water is quite challenging, as the metals are nonbiodegradable in nature and persistent in the environment. Heavy metals such as arsenic (As), chromium (Cr), mercury (Hg), cadmium (Cd), lead (Pb), and copper (Cu) when present in the water at a concentration above the permissible limit can have severe deleterious effects on both plants and animals. They are cytotoxic at a very low concentration and can cause several life-threatening diseases in humans. Conventional techniques for their removal include chemical precipitation, chelation, oxidation-reduction, ion-exchange, etc. These methods are costly and produce toxic sludge as secondary pollutant. Bioremediation has thus emerged as an attractive, economical, and eco-friendly alternative. The role of different microbes such as bacteria and algae in the remediation of heavy metal pollution is currently being enormously investigated. These microbes have shown great adaptability with respect to tolerance and survival in the presence of elevated concentrations of these metals. Bacterial and algal biomasses act as potential biosorbents that can be effectively applied as a part of sustainable treatment for the reclamation of heavy-metal-contaminated water in different wastewater treatment plants.