Changes of the Physico-Chemical and Microbiological Properties during Composting for Composting of Sewage Sludge

하수슬러지의 퇴비화과정 중 이화학성 및 미생물상 변동

To study the possibility of agricultural utilization of sewage sludge, the changes of the substances physico-chemical and microbiological properties composting periods such as inorganic matter, the form of organic matter and nitrogen and the kinds and the population number of microorganisms were investigated. The results were summarized as follows ; Temperature and $CO_2$ generation, they were the highest in the second day of composting periods and then were gradually fallen. pH value was not changed in first day during composting periods, but in second day was rapidly increased and then it was constant of the range of 8.4∼8.6. The contents of $P_2O,\;K_2O$, CaO and Fe were a little increased during composting periods, while that of ${SO_4}^{2-}$and Mn were big increased with 253${\sim}$331% and 191${\sim}$208% in late composting periods in comparing with early composting periods, respectively. The contents of ether extracted materials, water soluble polysaccharides, hemicellulose and cellulose were decreased but that of resins and lignin were not changed during composting periods. The contents of total and organic nitrogen during composting periods were decreased with 15${\sim}$20% and 22${\sim}$35%, respectively, while that of inorganic nitrogen was decreased with 75${\sim}$116%. The population numbers of microorganism during composting periods was much too changed according to the kinds of microorganism and composting periods.

하수슬러지를 퇴비화하여 농지이용가능성을 조사하기 위하여 하수슬러지에 수분조절제로 톱밥 또는 왕겨를 처리하여 퇴비화과정중 무기성분변화, 유기물 및 질소의 형태변화, 미생물종 및 개체수의 변화 등의 물질변화를 조사하였으며, 그 결과는 다음과 같다. 퇴비화과정중 온도 및 $CO_2$발생량은 퇴비화 2일에 최고에 달하였으며 그후 감소하였다. C/N율은 퇴비화가 진행됨에 따라 약간 증가하는 경향이었고, pH는 퇴비화 1일까지는 큰 변화가 없었으나, 그후 2일까지 급격히 증가하였으며 그후부터는 pH 약 8.4${\sim}$8.6 범위를 유지하였다. 퇴비화과정중 $P_2O,\;K_2O$, CaO, MgO 및 Fe함량 약간 증가하였으나,$SO_4$ 및 Mn은 퇴비화 초기에 비하여 후기에 각각 약 253${\sim}$331% 및 191${\sim}$208% 큰 폭으로 증가되었다. 퇴비화과정중 ether추출물질, 수용성 polysaccharides, hemicellulose 및 cellulose는 감소하였고, resins 및 lignin은 큰 변화가 없었다. 퇴비화과정중 총질소 및 유기태질소는 각각 약 15${\sim}$20% 및 22${\sim}$35% 감소하였으며, 무기태질소는 약 75${\sim}$166% 증가하였다. 퇴비화과정중 미생물 수는 미생물종 및 퇴비화기간에 따라 변화가 심하였다.