Additives to Enhance the Performance and Mechanism of Biogas Production from Agricultural Wastes: A Mini-review

Additives are an effective means of improving the performance of anaerobic digestion of agricultural wastes and can be well suited to deal with the inhibitory effects produced at various stages of digestion. There are significant differences in the role of different types or doses of additives in other mechanisms, so it is essential to take advantage of the benefits of various additives to enhance overall process performance. This paper presents a review of additives used in different stages of anaerobic digestion of agricultural waste in terms of gas production performance, including associated bacteria and enzymes for accelerating the rate of hydrolysis, zeolites for controlling ammonia-nitrogen concentration/conductive materials for improving acid accumulation, and trace elements that can supplement the nutrients required by microorganisms and chelating agents for enhancing nutritional activity. Finally, this mini-review emphasized that the dosage of additives should be reasonably controlled to maximize the gas production efficiency of the anaerobic fermentation system during the actual production application.