ABSTRACT
Algae are a highly diversified group of photosynthetic organisms, varying in size and shape, and occur in almost all marine and freshwater habitats. The removal of heavy metals by conventional methods is costly and inefficient when the concentration of metals is not very high (10 to 50 ppm), so the use of biological systems for the removal of heavy metals from dilute solutions has the potential to do so at lower cost. Algae are considered to have great potential for use in the removal of nutrients (e.g., trace metals) due to their high capacity to accumulate metals, in addition to the fact that they are sensitive to different test materials, their nutritional requirements are known, they have a high growth rate that allows to know in a few days the density and the effect caused by the toxic agent and their handling is relatively simple in the laboratory. Algae are very sensitive to metal toxicity and some species are used as biological biosensors to detect potential toxic effects of heavy metals. Toxic effects in microalgae can be caused by several mechanisms: (i) blocking of functional groups of biologically important molecules such as enzymes in the essential nutrient and ion transport system; (ii) displacement or substitution of essential metal ions from biomolecules and cellular functional units. The above may result in modification and inactivation of enzymes or disruption of cell membrane integrity. Therefore, the objectives of this chapter deal with the main algae used in the phytoremediation of heavy metals, as well as the main mechanisms of molecular interaction and biosorption.
