60

Bioremediation for Sustainable Environmental Cleanup

on the amount of adsorbed metal ions. Microbial cells have a surface made up of macromolecules

containing a lot of charged functional elements, such as:

• Phosphate

• Amino

• Carboxylic

• Hydroxyl

Due to the lack of carboxylic and phosphate acid residues, the cell surface is frequently

negatively charged. This enables passive cation binding on the cell surface. Positively charged metal

ions are drawn to the cell and adsorbed on the cell’s negatively charged surface (Kadukova 2016).

The entire process is passive and takes place without the cell’s metabolic processes. In Figure 4.2,

the entire cycle of wastewater treatment with biosorption is shown.

First, heavy metal ef

fluent is combined with biomass. Metal ions adsorb on the surface of

bacteria as a result of this (biosorption). After that, biomass regeneration (desorption) is carried out,

and metals can be collected from the leftover liquid portion (Leong and Chang 2020). The following

are the phases of a typical biosorption laboratory procedure:

I. A solution sample of volume V containing heavy metals at concentration Ci is created in the

first phase.

II. In the second step, biomass M (g) is added to the sample under investigation.

III. To achieve equilibrium, the solution with biomass is vigorously agitated for about 16 hr.

IV. The biomass is then separated from the solution in the fourth phase (centrifugation, filtration).

V. The solution is then analyzed for metal ions after being treated with biosorption (Cf ).

Figure 4.2. Removal and recovery of heavy metals from wastewater by microbial biomass.