A vast array of biological materials, especially bacteria, algae, yeasts and fungi
have received increasing attention for heavy metal removal and recovery due to their
good performance, low cost and large available quantities. The biosorbent, unlike
mono functional ion exchange resins, contains variety of functional sites including
carboxyl, imidazole, sulphydryl, amino, phosphate, sulfate, thioether, phenol, carbonyl,
amide and hydroxyl moieties. Biosorbents are cheaper, more effective alternatives
for the removal of metallic elements, especially heavy metals from aqueous solution.
In this paper, based on the literatures and our research results, the biosorbents
widely used for heavy metal removal were reviewed, mainly focusing on their cellular
structure, biosorption performance, their pretreatment, modification, regeneration/reuse,
modeling of biosorption (isotherm and kinetic models), the development of novel biosorbents,
their evaluation, potential application and future. The pretreatment and modification
of biosorbents aiming to improve their sorption capacity was introduced and evaluated.
Molecular biotechnology is a potent tool to elucidate the mechanisms at molecular
level, and to construct engineered organisms with higher biosorption capacity and
selectivity for the objective metal ions. The potential application of biosorption
and biosorbents was discussed. Although the biosorption application is facing the
great challenge, there are two trends for the development of the biosorption process
for metal removal. One trend is to use hybrid technology for pollutants removal, especially
using living cells. Another trend is to develop the commercial biosorbents using immobilization
technology, and to improve the biosorption process including regeneration/reuse, making
the biosorbents just like a kind of ion exchange resin, as well as to exploit the
market with great endeavor.