Efficient Anaerobic Co-digestion of Sewage Sludge and Food Waste Incorporating Qualitative and Phase Separation

As a byproduct of wastewater treatment plants, sewage sludge contains various types of pollutants, including antibiotics, heavy metals, parasitic eggs, and viruses. Anaerobic digestion is the primary method for sludge stabilization, widely used for resource recovery from and detoxification of sewage sludge. Conventional anaerobic digestion of sludge faces technical challenges such as low carbon-to-nitrogen ratio and low organic matter content. Co-digestion sewage sludge with food waste can effectively address these issues and improve system performance. Under high-solid conditions, anaerobic co-digestion of sewage sludge and food waste is influenced by many factors, and system performance can be enhanced through various pretreatment approaches. A novel anaerobic treatment process has been proposed, in which hydrothermally pretreated sludge and fermented food waste undergo synergistic anaerobic digestion. This process effectively addresses issues such as the slow hydrolysis rate of sewage sludge and the high content of recalcitrant organic matter in the co-digestion system. Additionally, the process provides insights into the transformation of humic acids during hydrothermal treatment of sludge and the fermentation patterns of food waste, providing a sound technology for the design of high solids co-digestion systems for treating sewage sludge and food waste.