Treatment of Industrial Wastewater with Microalgae

For some time, microalgae cultures have been studied in municipal wastewater bioremediation processes. It has been shown that they are an efficient alternative to remove pollutants from them, in this type of effluent the main pollutants are nitrogen and phosphorus, which are assimilated by microalgae for their growth, in the form of ammonium and orthophosphates, respectively. However, the treatment of industrial wastewater represents a difficult challenge to overcome due to the complexity of the effluents that vary according to the industry. This means that in some cases the effluents cannot be treated using microalgae cultures directly, but a previous treatment is needed to allow them to grow. Some investigations show us that the use of microalgae cultures in free state presents limitations in the treatment of industrial wastewater, due to the inherent toxicity of the effluent as well as the competition between native and foreign populations of microalgae as well as other microorganisms, whereas immobilized cultures on different supports provide the microorganisms with protection against the toxic effect of the substances present in the water being treated and with protection against predation by other microorganisms. In addition to this, the immobilization of the microalgae facilitates the harvesting process, reducing costs and facilitating the subsequent use of the harvested biomass. In this chapter, we will analyze the bioremediation capacity of microalgae in the treatment of industrial wastewater of different origins using free and immobilized cultures. The bioremediation process of industrial wastewater using microalgae should be managed as a virtuous circle where environmental service, biomass production, and the production of bioproducts with high-added value are considered.