href="#ulink_d77cd099-450b-50d2-a0dd-7f134f6075f6">Table 2.4 Biosorption of heavy metals by different yeasts.
| Yeast biomass(biosorbent) | Metal ions(biosorbate) | References |
|---|---|---|
| Candida utilis | Chromium | (Anaemene, 2012) |
| Saccharomyces cerevisiae | Cadmium | (Das et al., 2008) |
| Saccharomyces cerevisiae | Cobalt | (Arakaki et al., 2011) |
| Candida pelliculosa | Copper | (Apinthanapong and Phensaijai, 2009) |
| Mucor rouxii | Lead | (Muraleedharan et al., 1991) |
| Saccharomyces cerevisiae | Mercury | (Anaemene, 2012) |
| Saccharomyces cerevisiae | Nickel | (Siñeriz et al., 2009) |
| Thiobacillusthiooxidans | Zinc | (Nagashetti et al., 2013) |
Table 2.5 Biosorption of heavy metals by different plant materials.
| Plant waste | Metal | Adsorption capacity | Reference |
|---|---|---|---|
| Wheat bran | Mercury | 82% | (Farajzadeh and Monji, 2004) |
| Black gram husk | Lead | 93% | (Saeed et al., 2005) |
| Rice bran | Cadmium | 80% | (Montanher et al., 2005) |
| Baggase | Zinc | 90–95% | (Mohan and Singh, 2002) |
| Activated carbon of peanut shells | Nickel | 75% | (Wilson et al., 2006) |
| Barley straw | Copper | 80% | (Pehlivan et al., 2012) |
| Coconut shell fibers | Chromium | 80% | (Mohan et al., 2006) |
Animal waste products are dumped as solid waste in the environment without being processed or composted or simply washed into water canals, posing a health risk to humans and other living species. The chance to use animal waste for a useful purpose is lost if they are discarded without preparation. Some research has looked into using these animal waste products as a viable adsorbent to adsorb heavy metals from effluent because they are inexpensive and conveniently accessible. Heavy metal adsorption has been researched using animal manure as an adsorbent. Animal bones, pretreated fish bones, crab shells, pretreated arca shells, pretreated crab and arca shells, eggshells, Muscadomestica, and so on are a few other examples (Srivastava et al., 2016). Table 2.6 summarizes the results of the adsorption analysis performed on animal byproducts.
Table 2.6 Biosorption of heavy metals by different animal wastes.
| Animal waste | Metal | Adsorption capacity | Reference |
|---|---|---|---|
| Pretreated fish bones | Copper | 150.7 mg/g. | (Kizilkaya et al., 2010) |
| Dried animal bones | Zinc | 0.1764 mmol/g. | (Banat et al., 2002) |
| Crab shell | Cobalt | 322.6 mg/g | (Vijayaraghavan et al., 2006) |
| Pretreated arca shell biomass | Lead | 18.33 mg/g | (Dahiya et al., 2008) |
| Animal bone | Nickel | 7.22 mg/g | (Al‐Asheh et al., 1999) |
These adsorbents could offer significant advantages compared to currently available economically priced activated carbons and help with waste reduction. Furthermore, research is required to adapt the simulation methodology to larger manufacturing facilities rather than small experimental applications.
Biocomposites
Biocomposites consist of composite materials up of multiple ingredients that are mixed to make a new product that outperforms the individual constituent materials. They constitute biomass‐based products that are biodegradable, high‐performing, and environmentally friendly and can be utilized for wastewater treatment. Biopolymers such as cellulose, chitosan, starch, chitin, alginate, and others continue to be the most important part of biocomposites. Biopolymers’ advantages include their non‐toxicity, availability, economics, and environmentally friendly nature (Zhang et al., 2013).
Alteration of Biosorbents
The amount and accessibility of binding sites on the surface of an adsorbent determine the biosorption technique. Usage of biosorbents in their natural state has shown a number of drawbacks due to their poor biosorption potential and unpredictable physical stability. Modifying the surface features of biosorbents can have a huge impact on the biosorbents’ ability to remove metal particles (Gupta et al., 2002). Several researchers concentrated on altering the biomass chemically such that structural stability and effective heavy metal ion biosorption capability can be achieved.
Hydrophobicity, water absorbency, thermal resistance, cation/anion exchange capacity, and ability to resist microbial attack have been improved significantly by modifying the surface of biomass. Physical pretreatment methods such as heating, chilling, drying, lyophilization, and autoclaving are used to alter the cell surface. Several researchers have reported using chemical pretreatments for surface alteration, including washing with mineral and organic acid solutions, detergents, alkaline solutions, and organic compounds (Vieira and Volesky, 2000). These
