Thermochemical conversion of livestock manure to produce fuel and reduce odor: A feasibility study

Thermochemical conversion process (TCC) is a chemical reforming reaction of organic compounds in a heated and pressurized enclosure under anaerobic conditions. In a TCC process, macromolecules, such as cellulose, can be broken into small molecules that typically have four to ten carbon chains such as oils and single carbon molecules such as methane, carbon dioxide and carbon monoxide. Despite the TCC technology had been studied using coal and wood sludge as feed stock during the oil crises in the 1970's, the research was not sustained because of the low oil prices and high cost of the feed stock and catalysts (sodium and carbon monoxide). The TCC process, however, could be applied to livestock manure - a cost-less feed stock. In fact, manure is a much more desirable feed stock compared with liquidated coal and wood sludge because it is a uniform material, rich in energy and nutrient contents and contains adequate catalysts such as sodium and carbon monoxide generated at the early stage of the process. In this preliminary study, a 500-gram swine manure sample with 20% solid and 80% of water content was processed in a cylinder-shape reactor. The pressure varied between 13.6 and 34 bars and the temperature varied between 250 and 490 degrees C. As results, 19.1% of raw manure was converted into low-sulfur oils and 7.2% into methane. Since the TCC is a closed-loop process, odor can be potentially eliminated and waste can be better managed. Research is being conducted to optimize the temperature and pressure and to evaluate the economic viability of the TCC applied to livestock waste.