Overview of bioremediation as a method for metal-contaminated wastewater treatment

The global need to increase access to drinking water grows at the same rate as the contamination of water matrices due to anthropogenic activities and environmental disasters. Solutions require multidisciplinary and innovative approaches. A promising technology for water purification is bioremediation, wherein biomass, mainly from plants, algae, bacteria, and fungi, is used to remove environmental contaminants. Bioremediation efficiency has already been proven in historical environmental disasters such as oil spills into the sea. However, progress is still needed to enable the scalability for implementation in different environments and other pollutant types. This review highlights the ability of cells and biomaterials prepared from them to absorb, adsorb, or retain metallic ions, aiming to subsidize the implementation of bioremediation as a first-choice technique for cleaning wastewaters originating from ore tailings, wetlands, drainage, tannery effluent, and other industrial and domestic wastes. Research has shown that the success of bioremediation depends on a set of conditions, including the organism to be used, the site to be decontaminated, and the speciation of the metal. In addition, innovative technologies such as genetic engineering and nanotechnology can enhance bioremediation efficiency. The data presented show that these renewable materials can remove significant amounts of toxic metals in laboratorial conditions as well as in real hazardous waste. The results point to the need for greater investment in research to develop novel biomaterials and more public policies so that sustainable water purification techniques can be applied, especially for the benefit of communities with precarious access to drinking water.