| Summary: | Heavy metals are derived from various sources and majority of their associated pollutants enters water resources. Most of them are dangerous to humans and the environment due to their toxicity and carcinogenicity. Some of them, such as cadmium, lead, and chromium in low concentrations, also have toxic effects. The removal of heavy metals from wastewater has been considered in recent years due to environmentally protection regulations. Industrial wastewater containing heavy metals must be treated before being discharged into the water stream, but the treatment process is costly. Research and development of new and efficient methods with the lowest cost and highest efficiency in the removal of harmful environmental pollutants such as heavy metals are one of the current efforts of human society. Cost-effective and reusable adsorbents can be used in industry. Conventional methods have their own disadvantages; hence, there is a great interest in recognizing and using available and environmentally friendly biological materials and their commercialization. This study was literature review based in which several papers were reviewd from different databases available. The results of this study showed that biological treatment by fungi, yeast, bacteria, and algae has advantages over conventional methods such as cost reduction, reduced waste sludge, lower energy consumption, higher efficiency, biomass reduction capacity and less environmental pollution. Comparison between green, brown and red algae species for cadmium and lead removal showed that brown algae adsorption capacity with a maximum adsorption capacity of 239.1 mmol/g was higher than other algae species.
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