Hydrothermal conversion of municipal organic waste into resources

Sub- and supercritical water have been focused on as an environmentally attractive reaction media where organic materials can be decomposed into smaller molecules. We applied a hydrothermal reaction in subcritical water to the treatment of rabbit food as a model municipal solid waste. The reaction was carried out in a batch reactor at the temperature range of 473-623 K or in a semi-continuous reactor with the temperature profile from 473 to 573 K. The liquid reaction products were separated into water-soluble and water-insoluble parts. The water-soluble part was analyzed in terms of glucose and organic acids. For the batch reactor, the largest amount of water-soluble component was approximately 50%. Major organic acids detected were acetic acid and lactic acid. The largest yields were 2.6% for acetic acid and 3.2% for lactic acid. The largest yield of glucose was 33% at 523 K. For the semi-continuous reactor, the glucose yields were 11.5%, 3.9% and 8.7% in each fraction obtained at 473, 523, and 573 K, respectively. (C) 2003 Elsevier Ltd. All rights reserved.