Maturing process of city refuse compost during piling

Abstract

The maturing process of city refuse compost produced in a composting factory was characterized. During the piling of city refuse compost, the temperature in a windrow rose rapidly to 70–80°C, and then dropped, but rose again within a few hours by turning. This pattern was repeated even after the organic composition of the compost had become almost constant. The total carbon content, the C/N ratio, the contents of cellulose and hemicellulose, and the ratio of the carbon in reducing sugar to the total carbon decreased. The contents of total nitrogen, ash, and lignin increased relatively. The content of hot-water soluble organic matter did not show any clear tendencies. The contents of all the constituents in the city refuse compost, which was piled with turning and aeration, became almost constant after about 5 weeks, and thereafter changed little. The cation-exchange capacity (CEC) of the city refuse compost increased up to 70–80 meq/100 g during 5 to 8 weeks, and thereafter showed an almost constant value. The organic composition and the CEC of the compost piled without turning for 12 weeks were comparable to those of the compost piled with turning and aeration for 2 to 3 weeks. It was confirmed that the total nitrogen content, the C/N ratio, the ratio of the carbon in reducing sugar to the total carbon, and the CEC represent useful parameters for estimating the degree of maturity of city refuse compost.