Symbiosis of microalgae and bacteria consortium for heavy metal remediation in wastewater

Heavy metals in industrial wastewater are hazardous, not easily biodegradable, and can be enriched in the food chain. This will lead to serious global environmental problems. Traditional physicochemical heavy metal remediation treatments have limitations, including high costs and secondary contamination. However, biosorption is an effective and affordable way for treating wastewater containing heavy metals. A large specific surface area of microorganisms makes them attractive as biosorbents for the removal of heavy metals. In particular, more benefits exist for heavy metal adsorbents when microalgae and bacteria are combined. The combined system biological adsorption method of microalgae and bacteria is an ideal method for the remediation of large volume and low concentration heavy metal wastewater. The reuse of biological biomass of algae and bacteria resources can also be achieved. Therefore, it has very promising application prospects. This present review aimed to discuss the removal of heavy metals from wastewater using presently applied conventional treatments followed by the treatment using consortia of microalgae-bacteria, modes of microalgae-bacteria consortia system, the advantages of microalgae-bacterial consortia as biosorbents, the mechanisms of biosorption for heavy metals and the factors affecting the biosorption efficiency of heavy metals. Moreover, the feasibility of industrial applications and the potential product applications of harvested microalgae-bacterial consortia were also discussed. This review is foreseen to bring significance to industrial stakeholders including engineers, environmental technologists and business entities in developing and investing in more effective ways of bioremediating heavy metals from wastewater, for overall environmental sustainability.