The treatment of heavy-metal-bearing wastewaters is a critical environmental challenge, as access to clean drinking water becomes increasingly difficult due to pollution and rising water treatment costs. Traditional adsorbents derived from fossil fuels are not sustainable and can contribute to secondary pollution. To address this issue, researchers have turned to biogenic sorbents made from modern biomass as a promising alternative. These biosorbents utilize biological waste materials that would otherwise contaminate water systems, promoting a circular economy and sustainable water treatment practices. This chapter explores the potential of biogenic sorbents for water decontamination, focusing on their use in the removal of heavy metals from contaminated waters. Further, this chapter delves into the preparation methods, adsorbent types, adsorption mechanisms, and regeneration techniques employed with these biosorbents.
TopHeavy metal pollution is a substantial environmental distress, from the industries particularly mining, metallurgy, and energy harvesting units releases large quantities of toxic metals into the environment (Vardhan et al., 2019). Those heavy metals, including mercury (Hg), lead (Pb), chromium (Cr), and cadmium (Cd), cause a serious menace to living bodies’ health and ecosystems(Vardhan et al., 2019). Conventional methods for eradicating heavy metal ions from aqueous solutions, such as chemical precipitation and electrochemical treatment, are habitually unproductive and produce large amounts of slurry. Therefore, different approaches are being required to address this persistent concern. One such methodology is biosorption, which utilizes biological materials to remove heavy metals from aqueous solution(Eccles, 1995; Sheng et al., 2004). Biosorption is the method in which living or dead biomass as well as cellular products like polysaccharides, sequesters metal ions through various physicochemical mechanisms(Veglio’ & Beolchini, 1997; Volesky & Holan, 1995; Witek-Krowiak et al., 2011). It provides numerous advantages over traditional methods, comprising high efficiency, quick metal removal, and cost-effectiveness. Biosorption has multiplied its significant attention in recent years as a prospective solution for the treatment of high volume, low-concentration complex waste waters having heavy metals(Zouboulis et al., 2002).
The background mechanisms accountable for biosorption are not yet fully understood but are supposed to involve ion exchange, complexation, coordination, adsorption, electrostatic interaction, chelation, and micro precipitation. Biomass materials for example bacteria, fungi, yeast, and algae have been comprehensively experimented as potential biosorbents owing to their metal-binding capabilities. These biosorbents can meritoriously sequester heavy metal ions from dilute complex solutions, making them energetic candidates for the treatment of wastewater. Biosorption can take place through both metabolic and non-metabolic pathways(Reddy et al., 2012). Metabolic biosorption includes the active uptake of metal ions by living biomass. Non-metabolic biosorption, in contrast, take place through impulsive physicochemical processes and does not necessitate the expenditure of ATP. Both living and deceased biomass have been found to demonstration of biosorption properties which making them suitable for metal removal applications(Vijayaraghavan & Yun, 2008; Witek-Krowiak & Harikishore Kumar Reddy, 2013).
Figure 1.
Biosorption method for heavy metal removal (adopted from Elgarahy et al., 2021 under creative common license)
A several varieties of biomaterials has been studied for their biosorption capabilities. These biomaterials can be categorized into several categories, including bacteria, fungi, yeast, algae, industrial wastes, and agricultural wastes(Aksu, 2005; Tran et al., 2019; Vijayaraghavan & Yun, 2008). Bacteria, in particular, have been broadly experimented for their metal-binding capacities. Certain species of bacteria, such as Bacillus subtillis, have ascertained high metal sequestration abilities. Fungal biomass, including species like Rhizopus arrhizus, has also shown the capacity as a biosorbent for heavy metal removal(Behloul et al., 2017). Yeast, such as Saccharomyces cerevisiae, and algae, as well as brown algae like Sargasso seaweed, have likewise been studied for their metal-binding capabilities. Industrial and agricultural wastes, such as waste biomass from fermentation, food industries and corn cores, respectively, have been acknowledged as possible biosorbents due to their low cost and availability(Huang et al., 2020).