Anaerobic Co-Digestion of Microalgae and Industrial Wastes: A Critical and Bibliometric Review

Microalgae are photosynthetic organisms able to grow faster than land plants and produce biomass with relatively high energy potential. Accumulated high-value compounds like lipids, minerals, or proteins have focused the attention of scientists due to the potential production of biofuels and other value-added products. However, several drawbacks regarding both the biochemical structure of these organisms and technological difficulties have prevented the industry for implementing a comprehensive low-cost process regarding energy and environmental contamination. Among these technologies, anaerobic digestion (AD) has greatly increased research attention because of its simplicity and the ability to produce easily recycle by-products. Moreover, anaerobic co-digestion (AcoD) has shown promising results as a method to bypass the AD problems of microalgae as a sole substrate. This review is focused on the recent trends and comparison of the AcoD process to maximize energy recovery from microalgae biomass and agro-industrial wastes. The yield of methane gas among the studied bibliography is compared and a critical review of published data and methods used is included.