Heavy Metal(loid) Remediation Using Bio-Waste: A Potential Low-Cost Green Technology for Cleaning Environment

Introduction

Industrialization, urbanization and population explosion are the prime reason for tremendous environmental pollution in last few decades (Bhakta, Son, & Munekage, 2009; Bhakta & Munekage, 2010). Massive amount of pollutants generating from anthropogenic activities are indiscriminately discharging into the environment which contaminating the life system through the food chain (Jillian, Robert, & Rajakaruna, 2015). Effluents from industries like chlor-alkali, electrical, electronic, electroplating, glass manufacture, photography, oil refinery, pesticide, paint-pigment, plastic, paper and pulp, pharmaceutical, gun, steel etc. contain heavy metals such as, Hg, Cd, Pb, Cr, Cu, As, Ni etc (Tack, Vanhaesebroeck, Verloo, Rompaey, & Ranst, 2005). in extensively high concentration and are disposed into sea, river, canal or pond directly and contaminate them. These metals percolate into ground water and contaminate. Irrigated water is also not safe from heavy metals. Aquatic plants and animals and ultimately human beings are being affected greatly. Domestic wastes (such as, batteries, paints, electrical and electronics goods etc.) have also similar contribution.

Heavy metal(loid)s are hazardous, biologically non-essential, non-biodegradable and persistent in nature and have severe several toxic impacts on lives (Bhakta, Ohnishi, Munekage, Iwasaki, & Wei, 2012). They enter into the body of plants and animals through absorption of water in plants and drinking of water and ingestion of food in animal and get accumulated within tissue. These metals bind to functional groups such as amino (-NH₂), imino (=NH), sulfhydryl (-SH), carboxyl (-COOH), phenolic (C₆H₅-), phosphoryl (-P₂O₅), imidazole (C₃H₄N₂) and phosphate (-PO₄) of bio-molecules and form stable coordination complexes within the tissues (Perez Marín, Aguilar Meseguer, Ortũno, & Śaez, 2008; Gönen & Serin, 2012). They tend to form more stable complexes with sulphur and nitrogen ligands than oxygen ligand. Thus, heavy metals are accumulated in liver, kidney, brain, bones, teeth, lungs and blood and damage and impair various systems in human. This accumulation when crosses the critical level causes death of the living machine.

Therefore, decontamination of environment from the severe pollution of heavy metal(loid)s is an urgent issue to scientists. To overcome this problem, many technologies have been developed by researches, sorption, precipitation, coagulation, membrane filtration, etc. so far. Sorption is one of the important technologies in treating the polluted water using various inorganic (chemical) and organic based sorbent media in this respect. However, most of them are expensive and having adverse impact to environment. There is always significant demand in developing the low-cost green eco-friendly technology in this respect. In recent years, biomass based sorbents have drawn much attention to the scientist for applying as a potential sorbent in treating various pollutants of polluted water especially heavy metal(loid)s. Most common domestic biomass wastes (such as - banana peel, orange peel, cotton fiber, cellulose paper, Eichhornia plant, coconut coir, waste tea leaf etc.) and different industrial and agricultural bio-wastes (such as, sugarcane baggasse, rice husk, wheat and rice straw, pineapple crown top, sun flower stalk, olive stone, sea weeds, crab shell etc.) have the capability in binding of heavy metal by the process of adsorption and /or absorption, and thus, they can remove heavy metals from polluted water significantly.

The objective of this chapter is to evaluate the bio-sorbent potentiality of biomass waste as a potent low-cost agent of eco-technology in the heavy metal(loid)s remediation of environment. The chapter also concisely discussed applicability of various bio-wastes for remediation of heavy metal(loid)s from contaminated aquatic ecosystem or aqueous solution without harming environment.