Sustainable biogas mitigation and value-added resources recovery using methanotrophs intergrated into wastewater treatment plants

Methane is classified as the second major greenhouse gas with a global warming potential 25 times higher than carbon dioxide. Wastewater treatment plants (WWTPs) are considered as one of the main anthropogenic sources for global methane emissions. Utilizing the anaerobic digestion driven biogas, methanotrophs can offer a prominent solution for coupling methane mitigation with value-added resources recovery. Hence, methanotrophs can play a pivotal role in the paradigm shift to consider wastewater streams as proactive energy and value-added material resource instead of waste requiring further treatment. This review is destined to summarize the recent accomplishments in three methanotrophic-based biotechnological applications which are methanol, biopolymers production and biological nitrogen removal processes. Moreover, methanotrophs taxonomy, metabolism, and growth conditions are reviewed. In addition, the possibility to link the aforementioned applications within the operation of existing WWTPs in order to transform “energy-consuming treatment processes” into “energy-saving and energy-positive systems” is discussed.