Wastewater containing heavy metals (HMs) beyond permissible limit has to be decontaminated by an appropriate treatment method. Numerous conventional methods have been applied for heavy metal decontamination including chemical precipitation, ion exchange, electrolysis and membrane applications, etc. Most conventional methods are less efficient for the decontamination of metals due to the resistance and persistence of HMs in wastewater. Even so, the conventional methods have their limitations; adsorption using low-cost hybrid bioadsorbents has been explored as an environmentally friendly method for the removal of metal ions from wastewater. This review has been summarized the sources and effects of different heavy metals in the water/wastewater. The possible treatment methods also highlighted their advantages and limitations. Factors affecting the biosorption process such as bioadsorbent dosage, solution pH, contact time, initial concentration, temperature, and ionic potentials attracting to metal ions have been evaluated by the published researches. Moreover, the possible mechanisms of metal biosorption were discussed in light of previous studies. According to this review, hybrid bioadsorbents are outstanding materials due to their exciting physicochemical properties and other characteristics including eco-friendly nature, low cost, nontoxic, high adsorption capacity, and reusability. This review could be considered as a precious pathway for exploring more low-cost, environmentally friendly hybrid adsorbents for metal decontamination from wastewater, eventually, the review will contribute to environmental remediation and purification applications of biomaterials.

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