Application of Self-Heating Test for Indirect Estimation of Respirometric Activity of Compost: Theory and Practice

The self-heating test is widely adopted at solid waste composting plants as a simple and inexpensive test to determine the biological stability of the produced compost. Among other stability measures, the popularity of the respirometric activity determined by oxygen uptake rate is also increasing. However, the determination of respirometric activity by the respirometer is comparatively complicated and expensive. Therefore, in this study an attempt was made to determine indirectly the respirometric activity, using easily available data from the self-heating test. Experimental and theoretical analysis show that (i) the self-heating test could serve two purposes namely, (a) determination of the stability index of the compost; and (b) indirect estimation of respirometric activity; and (ii) the estimated respirometric activity based on the heat energy balance of the self-heating test compares well with the conventional method and could be used as a stability index for compost.