The determination of biological stability of composts using the Dynamic Respiration Index: The results of experience after two years

Biological stability was ascertained by using the Dynamic Respiration Index (DRI) on 144 samples of compost during the years 2003 and 2004, as a routine service for private subjects. Data obtained were collected and are critically discussed in this paper by using other parameters registered during tests, i.e., biomass temperature ( T ), specific airflow rate ( Q s ) and biomass analytical data (pH). Good linear correlations were obtained for DRI vs. T , DRI vs. Q s and DRI vs. pH, confirming expected results based on the theoretical discussion. Consequently, using the analytical method proposed in this paper means both T and Q can be used as additional parameters for measurement of the biological stability of compost. As a result, T values of 25.8 and 30.5 °C, and specific airflow rate of 8.6 and 13.4 m 3 Mg −1 VS h −1 were found corresponding to 500 and 1000 mg O 2 kgVS −1 h −1 , which, respectively, indicate a high and a medium degree of biological stability.