Microalgal Bioremediation of Emerging Contaminants in Domestic Wastewater

Contaminants in municipal sewage are generally organic and inorganic, originating from households and industrial activities. Some are categorized as heavy metals, nutrients (nitrates, phosphates), and emerging contaminants (ECs) such as pharmaceuticals and personal care products (PPCPs) associated with lifestyle in a known area. Because of their physicochemical properties, they tend to accumulate in sewage sludge during wastewater treatment. Treatment processes can still be expensive and partially effective. Rather, high concentration of ECs in municipal sewage might have a significant influence on treatment costs. Thus, there is a need for new approaches that are effective to remove these contaminants. Algae bioremediation through metabolic and cometabolic pathways could be a promising approach if combined with microbial consortia or other advanced biotechnological technologies to degrade ECs. The algal removal mechanisms involve bio-absorption, bioadsorption followed by biotransformation, which can be achieved intra- and extra-cellularly. In the process, microalgae supply oxygen to microorganisms, and CO2 generated during wastewater treatment is utilized by the microalgae. Acclimatized culture could be effective for ECs present in sewage at a concentration ranging from ng/L to µg/L.