Heavy Metal Contents of Compost from Household Food Waste

음식쓰레기 퇴비화과정 중 중금속함량 변화

The heavy metal concentration in mixed and separately collected household food waste, and their compost during the composting period was analysed. The mixed and separately collected food waste had Cd content of 8 mg/kg in spring and its content of 13 mg/kg in winter respectively. Its content was higher than by-product compost limit value(5 mg Cd/kg). Cd concentration in separately collected food waste in a house was higher in January, February, April and May than by-product compost limit value (5 mg Cd/kg). When Cd concentration in the initial composting material was higher than 5 mg/kg, its concentration in the compost of household food waste during the composting period was higher than by-product compost limit value, but it was not accumulated in the compost during the composting period. Fly ash was added to separately collected household food waste to adjust its moisture content for composting. Its addition had moisture conditioning and Cd concentration reducing effect in the compost. The average one month composted fresh compost from the mixed collected household food waste was matured in a pile out of doors for 7 months with turning the pile once a month and its heavy metal concentration was examined. Accumulation of the heavy metals in the compost did not occur during the composting period, because they were washed out during the rainfall.

가정에서 분리수거한 쓰레기와 혼합쓰레기 및 퇴비화 과정중에 있는 쓰레기의 중금속 농도를 측정하였다. 카드뮴의 농도는 봄철에 8 mg/kg 쓰레기, 겨울철에 13 mg/kg 쓰레기였다. 중금속의 농도는 월별로 큰 차이를 보였으며 1월과 2월, 4월, 5월에는 카드뮴의 함량이 부산물 퇴비의 기준인 5 mg/kg 쓰레기의 농도를 초과하였다. 가정쓰레기가 혼합되기 전 분리수거된 음식쓰레기의 퇴비화 과정중에 카드뮴의 함량을 측정한 바, 봄철과 겨울철에 부산물 퇴비화의 기준치를 초과하였다. 분리수거된 가정쓰레기에 수분조절제로 첨가된 석탄회는 퇴비중의 중금속 함량을 낮추는 효과가 있었다. 소형 퇴비화 용기에서 1개월 퇴비화한 음식쓰레기를 야외에서 야적하여 숙성시켰는데, 이 기간동안에 중금속의 축적은 일어나지 않았다.