Bioaccumulation and Biosorption: The Prospects and Future Applications 61

The following formula (Eq. 4.1) is used to compute biosorption in mg metal per g biomass:

v(c

=

i ^{– c}f⁾

q

Eq. 4.1

M

where:

q – number of adsorbed metals (mgg^–1)

V – is the sample quantity of the solution (in millilitres).

C

–1

i ^{– metal ion concentration in solution at the start (mg L )}

Cf – metal ion concentration in solution at the end (mg L^–1)

M – mass of biomass (g)

4.5 Bioaccumulation

Different elements from the surrounding environment are absorbed and retained by living organisms.

Bioaccumulation is the process of harmful metals or organic compounds being bound inside a cell

structure. The biological activity of the biomass is critical in the bioaccumulation process (Loppi et

al. 2020). As a result of their metabolic functions, cells must be alive in order to adsorb pollutants.

The procedure should be kept under constant control in order to get the intended results. During

bioaccumulation, metal ions are absorbed by the entire cell. Metals enter the cells of living beings

through the same pathways as nutrients do. Heavy metals are absorbed by unicellular organisms

with the help of essential minerals like calcium and magnesium (Louati et al. 2020). Plants absorb

nutrients from water or soil through their roots, whereas mammals absorb nutrients through their

digestive or respiratory systems. There are two stages of bioaccumulation. Metal ions are bonded

on the cell surface in the first stage. The metabolically passive phase of the process is identical to

the biosorption mechanism. Metal ions are then transferred into the cell. It is possible only when the

cells are metabolically active in the second half of this process (Maal Bared 2020).

The quantity of biomass grows if correct conditions for organism growth are maintained in the

second stage. In comparison to biosorption, this allows (Nguyen et al. 2020) for the binding of larger

amounts of metal ions (Maal Bared 2020). Precipitation can lead to metal accumulation in microbial

biomass. It is critical, however, that precipitated metals were linked to the cell. Citrobacter, for

example, generates phosphatase, an acidic enzyme. Heavy metals are precipitated in the cell wall

in the form of barely soluble acidic phosphate when this enzyme is present. Denitrification caused

by Achromobactin dentifrices contributes to environmental acidity and hence increases metal

precipitation. Polysaccharides found in the cell walls of fungus and algae, such as cellulose, chitin

and alginates, also help to capture metals (Naik and Dubey 2013).

4.6 Comparison of Biosorption and Bioaccumulation

Biosorption is a metabolically gradual process that does not involve any metabolic activity. As a

result, the biomass used in the biosorption process is not alive. Bioaccumulation takes place in the

presence of living cells and necessitates increased nutrition and energy inputs. There is also a need

to avoid the detrimental effects of heavy metals on cells, which could stymie the process (Parsania

et al. 2021). As a result, heavy metals with low concentrations that impede microbial growth should

be determined prior to bioaccumulation. Taking all these factors into account, bioaccumulation as a

heavy metals removal approach is more complicated and costly (Parsania et al. 2021). A comparison

of these two methodologies may be seen in Table 4.1.