Reduction of ammonia inhibition of organic matter degradation by turning during a laboratory-scale swine manure composting

Abstract

Inhibitory effect of ammonia on the organic matter degradation at the outer region was simulated using a composting system consisted of two miniature-scale reactors with different constant temperature connected in series. The lower and upper reactors were incubated at 70 and 40 oC, respectively. Composting runs were conducted with or without turning. The ammonia inhibition of organic matter degradation in the upper reactor was more severe during the earlier stages of composting without turning, i.e., 24─60 h, when the ammonia concentration supplied from the lower reactor exceeded 500 ppm, than that in composting with daily turning. Furthermore, the different degradation rate of organic matter between composting with and without turning corresponded to the difference in the growth of mesophilic bacteria that was considered to be affected by the ammonia. It was elucidated that turning reduced the ammonia inhibition of degradation of organic material during composting.