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Bioremediation for Sustainable Environmental Cleanup

Table 4.1. Comparison of Biosorption and Bioaccumulation.

Characteristics

Biosorption

Bioaccumulation

Cost

Low in most instances. The industrial waste can be

used to generate biomass. Most of the cost is spent

on transportation and biosorbent production.

Usually, it is quite high. The method is

performed in the presence of living organisms,

which must be preserved.

pH

The sorption capacity of heavy metals is influenced

by the pH of the liquid. The process, however can

occur in a wide pH range.

A considerable shift in pH can have a major

impact on living cells.

Selectivity

Poor modifications/biomass transformation, on the

other hand, can increase it.

Compared to biosorption, this is a significant

improvement.

Rate of removal

Many mechanisms occur at a rapid rate.

In comparison to biosorption, the pace is

slower. It takes a long time for intracellular

accumulation to occur.

Regeneration and

reuse

In many cycles, biosorbents can be regenerated

and reused.

Reuse is limited due to intercellular

accumulation.

Recovery of

metals

Heavy metal recovery is feasible with the right

eluent.

Biomass cannot be used for other purposes

even if that is possible.

Energy demand

Low

Cell growth necessitates the use of energy.

4.7 The Impact of Environmental factors on Biosorption and

Bioaccumulation

Many environmental parameters influence the efficiency of heavy metal biosorption and

bioaccumulation, including pH, temperature, contact time, concentration, biomass age and the

inclusion of other ions in a solution.

4.7.1 pH

As biosorption and bioaccumulation are analogous to ion exchange in some ways, the pH of a

solution has a big impact on heavy metal elimination. The amount of binding sites available on the

surface of cells is affected by pH (Deng et al. 2011). The accessible binding sites in a cell bind to

hydrogen cations in a solution when the pH is low. As a result, the number of accessible places is

limited, and fewer metal cations can be adsorbed. However, when pH rises, so does the amount of

active areas with a negative charge that attract cations (Devatha and Shivani 2020).

4.7.2 Temperature

Temperature affects the stability of metal ions in a solution as well as metal-cell complexes.

Temperatures between 20 and 35 degrees celsius, on the other hand, have little effect on biosorption

and bioaccumulation (Dey et al. 2020). Higher temperatures improve biomass sorption capability,

but they can also damage the sorption material.

4.7.3 Contact Time

Contact time between biomass and a metal-containing solution affects bioremediation. Both are

quick processes, with most metals being adsorbed right away (Fabre et al. 2020). Starting from the

moment the biomass is exposed to the solution, equilibrium is reached within the first few minutes.

4.7.4 Concentration and Age of Biomass

The degree of metal removal from the solution is also significant when there is a large concentration

of biomass in the solution. However, at high biomass concentrations, the ratio of bound metals to dry

matter is relatively low. Higher biomass concentrations result in the creation of larger cell aggregates,