과열증기를 이용한 음식물류폐기물 탄화물의 물리화학적 특성

Abstract

A carbonization of food wastes produces less moisture, less volatile compounds and more fixed carbon than a hot air drying process. This is due to relative higher efficiencies of water removal mechanism and volatilization phenomena. The removed water includes surface water, interstitial water and water bounded inside food wastes. The moisture contents were reduced by 4.28%, the volatile compounds were decreased by 15.3% and the fixed carbon contents were increased by 6.56%. The carbides produced from the carbonization of food wastes at 50oC were proved to be effective as fuel aids with heat capacity of 2,781 kcal/kg. The carbides showed pH range of 8~9.5 and the salt contents were about 1% that is a little higher than that of the original material. This is because the organic salts, which were converted into tar and re-adsorbed in the carbonization process, contributed to a higher salt contents of carbides. This slightly increased salt contents in carbides exhibit no potential harm to functional aspects as fuel aids. The carbides contain 178 ppm lead, 97.3 ppm chromium and 3.3 ppm cadmium that are by far below the standard limits suggested for the heavy metal contents of compost.