Do Kyoon Kim

Advanced Compost and Energy (ACE) System Converting Livestock Wastes to Resources by Exothermal Microbial Reactions: A Case Study

This study describes a type of conversion technology of livestock waste to resources, including energy and fertilizer production. The most difficult part when treating livestock wastes is how to remove a high content of water in them. Generally, livestock wastes from concentrated animal feeding operations contain 90% water by weight. Therefore, an existing treatment system must be equipped with a wastewater treatment system as well as liquid/solid separation process. Moreover, the accompanied wastewater system results in a high capital, and operational and maintenance costs of having an entire system. However, the advanced compost and energy system is able to treat livestock wastes in one system. Thus, the advanced compost and energy system is a cost-effective method. In the advanced compost and energy system, technically, a high water content in livestock wastes evaporate by an exothermal reaction caused from a specific group of aerobic fermentation microorganisms. The microorganisms produce heat higher than 80°C thus evaporating moisture retained in wastes, while digesting long-chain molecules of organic compounds in them. Livestock wastes include cow, hog, and poultry manures in this study. Food wastes were also comparatively tested along with livestock wastes. Resulting materials showed relatively high caloric value and energy yield, 4,500 kcal/kg, in a heating value test. Therefore, they can be directly used as refuse derived fuel without adding such coals, cokes, and oils as energy boost additives that are normally utilized for a conventional refuse derived fuel manufacture process. Solid materials from the advanced compost and energy system can also prevent any secondary pollution from an incomplete combustion. The advanced compost and energy system is also environmentally benign with a zero discharge and even resource production from waste materials, which was recognized through lab-scale and full-scale experiments.