Application of autothermal thermophilic aerobic digestion as a sustainable recycling process of organic liquid waste: Recent advances and prospects

Autothermal thermophilic aerobic digestion (ATAD) has been used to stabilize organic waste since the 1960s and is considered sustainable technology. ATAD has several advantages, including high biodegradation efficiency, pathogen inactivation, and ease of operation. Although ATAD research has a long history, the number of studies on ATAD is much lower than those on similar aerobic processes, particularly composting. Previous review articles addressed the origin, design, operational experiences, metabolism, and the microorganisms at the thermophilic stage of ATAD. This article reviews the digestion systems, applications, and characteristics of ATAD; compares system performance and microbial community structure of ATAD with those of other biological processes such as composting, activated sludge, and anaerobic digestion; and discusses the physicochemical properties and factors of ATAD. The challenges, opportunities, and prospects for the application of ATAD are also discussed. This review suggests that ATAD is feasible for treating organic liquid waste (1-6% total solid content) in small-sized towns and can help establish a sustainable society.