**1. Introduction**

Water plays an important role in the world economy. Majority (71%) of the Earth's surface is covered by water, but fresh water constitutes a miniscule fraction (3%) of the total. Water fit for human consumption is obtained from the fresh water bodies. Approximately, 70% of the fresh water goes to agriculture. This natural resource is becoming scarce at many places and its unavailability is a major social and economic concern [1]. Though access to safe drinking water has improved over the last few decades, it is estimated that five million deaths per year are caused due to consumption of polluted drinking water or drought. In many developing countries, 90% of all wastewater still goes untreated into the fresh water bodies making it unfit for human consumption, which either leads to scarcity or affects the human population [2]. The concern to protect fresh water bodies for a healthy population is a challenge in recent times.

Intoxication of heavy metals also leads to damage to the major systems in the body and may lead to an increased risk in developing cancers [7]. Metal ion pollution is highly persistent, and most of them are nonbiodegradable. The presence of various heavy metals such as chromium (Cr), lead (Pb), zinc (Zn), arsenic (As), copper (Cu), nickel (Ni), cobalt (Co), cadmium (Cd), and mercury (Hg) causes disturbances in circulatory, gastrointestinal, and nervous systems. They also affect various organs and lead to blindness, deafness, brain damage, loss of fertility, cancer, and many other severe health problems that ultimately cause death of the individual [7–9].

Application of Biosorption for Removal of Heavy Metals from Wastewater

http://dx.doi.org/10.5772/intechopen.77315

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Heavy metals like nickel, copper, zinc, cadmium, chromium, lead, and mercury are major pollutants that affect the fresh water reservoirs due to the discharge of large amounts of metalcontaminated wastewater from industries. Because of their persistent, non-biodegradable, and toxic nature, they accumulate in the environment such as in the food chain and cause serious health disorders. Over the last few decades, many conventional treatment methods have been used for the removal of heavy metals from contaminated wastewaters. The commonly used methods include chemical precipitation, ultra-filtration, ion exchange, reverse osmosis,

**Chemical precipitation** is the most widely used method for heavy metal removal from inorganic effluents. The conceptual mechanism involved is that the dissolved metal ions get precipitated by chemical reagents (precipitants) and result in the formation of metal hydroxides, sulfides, carbonates, and phosphates (insoluble solid particles) that can be simply separated

**Ion exchange** is based on the reversible exchange of ions between solid and liquid phases. An ion exchanger is a solid resin capable of exchanging both cations and anions from an electrolytic solution and releases counter-ions of similar charge in a chemically equivalent amount. **Membrane filtration** is capable of removing not only metal ions but also suspended solid and organic components. A membrane is a selective layer used to make contact between two homogenous phases with a porous or non-porous structure for the removal of pollutants of varied size. **Ultrafiltration (UF)** is a permeable membrane separation process with pore sizes in the range of 0.1–0.001 micron which permeates water and low molecular weight solutes, while retaining the macromolecules, particles, and colloids that are larger in size. The removal of Cu (II), Zn (II), Ni (II), and Mn (II) from aqueous solutions was achieved by using ultrafiltration assisted with a copolymer of malic acid and acrylic acid attaining a removal efficiency of 98.8% by forming macromolecular structures with the polymers which are rejected by the membrane [15].

**Microfiltration (MF)** works with the same principle as ultrafiltration. The major difference between the two processes is that the solutes which are removed by MF are larger than those rejected by UF. Cross-flow microfiltration (CFMF) in yeast-based bioaccumulation process was used for the removal of metal ions from tap water artificially contaminated with Cu (II), Cd (II), Pb (II), and Cr (III). The method was efficient for the removal of metal ions with an

electro winning, and phytoremediation, and they are introduced briefly [10–14].

**3. Conventional methods for heavy metal removal**

by sedimentation or filtration.

efficiency of 31, 7, 63, and 71%, respectively [16].

Industrialization to a larger degree is responsible for the contamination of environment especially water where lakes and rivers are overwhelmed with a large number of toxic substances. Heavy metals are reaching hazardous levels when compared with the other toxic substances [3]. Heavy metals are a unique group of naturally occurring compounds. Their continuous release leads to overconsumption and accumulation. As a result, people around the globe are exposed to adverse consequences of these heavy metals. Many industries (fertilizers, metallurgy, leather, aerospace, photography, mining, electroplating, pesticide, surface finishing, iron and steel, energy and fuel production, electrolysis, metal surface treating, electro-osmosis, and appliance manufacturing) discharge waste containing heavy metals either directly or indirectly into the water resources [4]. Toxic heavy metals, which are of concern, are chromium (Cr), lead (Pb), zinc (Zn), arsenic (As), copper (Cu), nickel (Ni), cobalt (Co), cadmium (Cd), mercury (Hg), and so on. As these metals are not biodegradable, they tend to accumulate in the living organisms and lead to various diseases and disorders which ultimately threaten human life. They can cause ill health, even when present in the range of parts per billion (ppb) [5]. Biosorption has emerged as an attractive option over conventional methods for the removal of heavy metal ions from effluents discharged from various industries which ultimately reach and pollute fresh water bodies. This chapter reports the toxicity of heavy metals, the advantages of biosorption, various biosorbents used for the removal of metal ions, effect of immobilization and modifications of biosorbents, various factors affecting the process of biosorption, different bioreactors used in biosorption, and the application of biosorption for the removal of metal ions from various wastewaters like industrial effluents and contaminated water resources. The recent advances, current status, and future of the process are discussed.
