Biosorption of heavy metals using non-living microbial biomass is a cost-effective method for decontaminating metal-bearing effluents. This process has advanced to the point where it is ready for large-scale application. Packed bed sorption columns are the most efficient equipment for continuous removal of heavy metals. The process involves loading, regeneration, and rinsing of the biosorbent. Regeneration allows for the reuse of biosorbents in multiple cycles, leading to metal-free effluents and concentrated metal solutions for recovery. Biosorbents are prepared from naturally available or waste biomass, such as algae, moss, fungi, and bacteria, which are inactivated and pretreated. Some biomass is immobilized in synthetic matrices or grafted onto inorganic supports to achieve desired mechanical properties. Biosorption columns operate in cycles, with regeneration producing concentrated metal solutions suitable for recovery. The process is efficient and economical, with the potential for continuous operation using parallel columns. Ion exchange is the primary mechanism of metal biosorption, with weakly acidic and basic functional groups in biomass playing a key role. Studies have shown that the uptake of heavy metals is influenced by pH, with higher affinity observed at lower pH values. The selectivity of biosorbents for heavy metals is comparable to commercial ion exchange resins, and the mechanism is now well understood. The sorption performance of biosorbents is evaluated using isotherm models, such as Langmuir and Freundlich, which describe the relationship between metal uptake and concentration. These models help in predicting the behavior of biosorbents under different conditions. The presence of multiple metals in solution complicates the sorption process, requiring careful evaluation of interactions between metals and the biosorbent. Ion exchange isotherms are used to model the sorption of multiple metals, with the equilibrium constant and separation factor determining the interaction between ions. The performance of biosorption columns is influenced by the ionic form of the biosorbent, with different forms affecting metal removal efficiency. The selection of appropriate ionic forms and regenerants is crucial for optimal performance. The biosorption process is also affected by the composition of the wastewater, with non-toxic species potentially interfering with metal removal. The efficiency of biosorption depends on the properties of the biosorbent and the characteristics of the wastewater. Models such as the Bohart-Adams and Equilibrium Column Model (ECM) assist in predicting the performance of biosorption columns and scaling up the process. Anion biosorption is also a growing area of research, with studies on the removal of anionic metals such as molybdate and hexavalent chromium. The mechanisms of anion exchange and metal reduction are being investigated to improve the efficiency of biosorption processes. Overall, biosorption offers a cost-effective and environmentally friendly method for the removal of heavy metals from industrial effluents.Biosorption of heavy metals using non-living microbial biomass is a cost-effective method for decontaminating metal-bearing effluents. This process has advanced to the point where it is ready for large-scale application. Packed bed sorption columns are the most efficient equipment for continuous removal of heavy metals. The process involves loading, regeneration, and rinsing of the biosorbent. Regeneration allows for the reuse of biosorbents in multiple cycles, leading to metal-free effluents and concentrated metal solutions for recovery. Biosorbents are prepared from naturally available or waste biomass, such as algae, moss, fungi, and bacteria, which are inactivated and pretreated. Some biomass is immobilized in synthetic matrices or grafted onto inorganic supports to achieve desired mechanical properties. Biosorption columns operate in cycles, with regeneration producing concentrated metal solutions suitable for recovery. The process is efficient and economical, with the potential for continuous operation using parallel columns. Ion exchange is the primary mechanism of metal biosorption, with weakly acidic and basic functional groups in biomass playing a key role. Studies have shown that the uptake of heavy metals is influenced by pH, with higher affinity observed at lower pH values. The selectivity of biosorbents for heavy metals is comparable to commercial ion exchange resins, and the mechanism is now well understood. The sorption performance of biosorbents is evaluated using isotherm models, such as Langmuir and Freundlich, which describe the relationship between metal uptake and concentration. These models help in predicting the behavior of biosorbents under different conditions. The presence of multiple metals in solution complicates the sorption process, requiring careful evaluation of interactions between metals and the biosorbent. Ion exchange isotherms are used to model the sorption of multiple metals, with the equilibrium constant and separation factor determining the interaction between ions. The performance of biosorption columns is influenced by the ionic form of the biosorbent, with different forms affecting metal removal efficiency. The selection of appropriate ionic forms and regenerants is crucial for optimal performance. The biosorption process is also affected by the composition of the wastewater, with non-toxic species potentially interfering with metal removal. The efficiency of biosorption depends on the properties of the biosorbent and the characteristics of the wastewater. Models such as the Bohart-Adams and Equilibrium Column Model (ECM) assist in predicting the performance of biosorption columns and scaling up the process. Anion biosorption is also a growing area of research, with studies on the removal of anionic metals such as molybdate and hexavalent chromium. The mechanisms of anion exchange and metal reduction are being investigated to improve the efficiency of biosorption processes. Overall, biosorption offers a cost-effective and environmentally friendly method for the removal of heavy metals from industrial effluents.