13.6 Industrial Application on the Biosorption of Heavy Metals

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13.6

Industrial Application on the Biosorption of Heavy

Metals

The removal or the treatment of contaminants by the specific type of biosorbents

was first patented in the year 1980. During 1990s, lot of researchers were focused

on the process of understanding the biosorption mechanisms and its fundamentals.

But this process is not widely applied for the removal of toxic metal and several com-

pounds [27]. There are various types of reactors used to investigate the biosorption

process like stirred tank bioreactors (SBRs), packed bed reactors, fluidized bed reac-

tors (FBRs), and fixed bed reactors (FxBRs). These reactors can be used to remediate

the heavy metals and the MCDs either by continuous, batch, or both continuous and

batch systems. The major physiochemical properties such as temperature, mixing,

agitation, pH, and nutrient availability have to be optimized.

13.6.1

Biosorption of Heavy Metals Using Fluidized Bed Reactor

Generally, the biosorption process is investigated using a fixed bed reactor due to

high concentration and uniform residence time. But the solid impurities present

in the wastewater will lead to persistence of the solid in the fixed bed and the liq-

uid must be cleared to overcome the column blocking. In the last two decades, the

fluidized bed reactors have been used for turbid liquids and also for avoiding chan-

neling issues [28]. In addition to that, the main advantage of using a fluidized bed

is to reach a proper mass and heat transfer between the fluid and particles and

also between the particle and sidewall of the column. In this process, the liquid or

gases flow with a certain velocity through the bed, and simultaneously the pressure

drop was emerged to balance the gravitational force on the particles, and finally,

the minimum fluidization velocity was achieved by further increasing the velocity

of liquid or gas phase [29]. The performance of a fluidized bed for the removal of

metal ions mainly depends on particle density, size of the particle, size distribution,

and surface characteristics. Illamathi et al. [30] carried out the experiments to study

about the biosorption of heavy metals such as Cr(VI), Ni²⁺, Cu²⁺, and Cd²⁺ by the

liquid–solid fluidized bed using sol–gels as catalysts which contain several bacteria

such as P. aeruginosa, Bacillus subtilis, and Escherichia coli as shown (Figure 13.1).

They achieved the maximum percentage of removal of copper, cadmium, chromium,

and nickel which was found to be 84.62%, 67.17%, 49.25%, and 61.02%, respectively.

The biosorption of cadmium, copper, and lead using cabbage leaves was done by

varying different physiochemical parameters such as specific surface area, the poros-

ity of the particle, and void space. The efficiency of the biosorption process in the

fluidized bed has been evaluated by different parameters such as superficial velocity,

bed height, and heavy metal concentrations, and the effectiveness of biosorption was

elucidated by the breakthrough curves of divalent ions like Pb(II), Cu(II), and Cd(II).

The fluidized bed which is shown in Figure 13.2 made up of glass with an inner

diameter of 7.5 cm and a height of about 100 cm, respectively. The influent flow

of metal contaminant through the bottom of the reactor by the 2-mm stainless

steel distributor and the pressure of the water were measured by the U-tube