What is biosorption?Biosorption is a property of certain types of inactive, dead, microbial biomass to bind and concentrate heavy metals from even very dilute aqueous solutions.It is particularly the cell wall structure of certain algae, fungi and bacteria which was found responsible for this phenomenonOpposite to biosorption is metabolically driven active bioaccumulation by living cells.
Advantages The major advantages of biosorption over conventional treatment methods include: Low cost; High efficiency; Minimisation of chemical and biological sludge; No additional nutrient requirement; Regeneration of biosorbent; and Possibility of metal recovery.
Mechanism The complex structure of microorganisms implies that there are many ways for the metal to be taken up by the microbial cell. The biosorption mechanisms are various and are not fully understood. They may be classified according to various criteria. According to the dependence on the cells metabolism, biosorption mechanisms can be divided into:1. Metabolism dependent and2. Non -metabolism dependent. According to the location where the metal removed from solution is found, biosorption can be classified as:1. Extra cellular accumulation/ precipitation2. Cell surface sorption/ precipitation and3. Intracellular accumulation.
Factors affecting Biosorption Temperature seems not to influence the biosorption performances in the range of 20-35 0C. Since biosorption is determined by equilibrium it is largely influenced by pH,the concentration of biomass and the interaction between different metallic ion. Biomass concentration in solution seems to influence the specific uptake: for lower values of biomass concentrations there is an increase in the specific uptake. Biosorption is mainly used to treat wastewater where more than one type of metal ions would be present; the removal of one metal ion may be influenced by the presence of other metal ions. For example: Uranium uptake by biomass of bacteria, fungi and yeasts was not affected by the presence of manganese, cobalt, copper, cadmium, mercury and lead in solution .
Environmental Uses Environmentally friendly filtering techniques. Rigorous filtering of harmful pollutants created by industrial process and all around human activity.
Biosorption In Industry Removal can be accomplished with biosorption techniques. It is alternative to using man-made ion exchange resin,which cost ten times more then biosorbents.
Common UsesUses of biosorption is seen inactivated carbon filters.They can filter air and water by allowing contaminants to bind to their incredibly porous and high surfaces structure.
Desorption Desorption is important for the regeneration of the sorbent for its more effective reused.The desorption process should:yield the metals in a concentrated form;restore the biosorbent to close to the original condition for effective reuse with undiminished metal uptake andno physical changes or damage to the biosorbent.
Lead biosorption by Mangifera sp Data in Table 1 reveals the biosorption of Pb2+ by Mangifera sp. biomass as afunction of initial concentration of blank solutions. Uptake capacity increases to 24.4mgg-1 and removal of Pb2+ from solution is more at low initial concentration, that is,maximum 92.003% at 26.01 mgl-1 concentration.Pb2+concent Ci Cf Ci-Cf q %ration (mgL-1) (mgL-1) (mgg-1 Removal 25 26.01 2.08 23.93 4.786 92.00308 50 48.07 6.65 41.42 8.284 86.16601 75 76.32 12.53 63.79 12.758 83.58229 100 102.21 13.71 88.5 17.7 86.58644 125 122.14 22.16 99.98 19.996 81.85689 150 147.41 25.41 122 24.4 82.76236
Linearized adsorption isotherm for Pb2+ on Mangifera sp. biosorbent.A. Langmuir isotherm; B. Freundlich isotherm.