Evaluation of Component Changes and Maturity During Composting Municipal Garbage

A composting system using municipal garbage from Beijing was conducted to probe transforming characteristics during composting process. The results showed that water content in the municipal garbage was appropriate to be composted. Both total nitrogen and total carbon contents decreased mostly in the first 15 days of composting, indicating this period was key time to control nutrient losses. During the composting process, the content of available potassium increased sharply, from 3 947 mg·kg-1 to 5 728 mg·kg-1. Organic phosphorus also increased from 85 mg·kg-1 to 305 mg·kg-1, but the contents of organic phosphorus was not enough for high quality fertilizer. Therefore, it was suggested to add some phosphorus in the compost product from municipal garbage. The seed germinating ratio from different periods in the course of the compost had little differences, and all of them were more than 85%, revealing that there were few inhibiting substances produced through the whole compost. The ratio of C/N decreased from 23 to 15, and, at the same time, the temperature declined to surrounding temperature. By the method of paper chromatography, the fringe of filter paper showed the irregular wave. The results of seed germinating ratio, C/N and paper chromatography all showed that the compost of municipal garbage showed in maturity after 40 days composting.