A thematic review on livestock manure treatment strategies focusing on thermochemical conversion

Livestock manure (LSM) management is emerging as a challenge due to increasing livestock consumption. Owing to the decreased agricultural land area, it is necessary to ensure LSM utilization in non-agricultural fields. LSM can be a valuable resource if managed as a circulating resource. This study discusses research trends based on a literature review and classifies LSM treatments. The analysis of each treatment is presented according to research trends, and implications for the future LSM processing are discussed. “Biological treatment” accounted for the largest portion at 48%, “manure management,” which suggests improvement in manure treatment through systematic thinking or LSM management practices, accounted for 16%, and “thermochemical conversion” accounted for 11%. In addition, “life cycle assessment (LCA) research,” “solid-liquid separation approach,” and “nutrient-recovery/losses” were derived. Studies on biological treatments are increasing. Although anaerobic digestion (AD) is the most used method, it has the disadvantages of long processing time and waste generation after processing. As a key supplement, thermochemical conversion (TCC) technology, which could overcome the disadvantages of AD, was reviewed.