Analyzing the stability level of organic waste by the static respiration index and dynamic respiration index

Stability is a parameter that reveals the extent of decomposition of biodegradable organic matter. Various methods are employed to measure the stability level of organic materials, including the static respiration index (SRI) and dynamic respiration index (DRI). In this study, the characteristics and stability of food waste, garden waste, municipal organic waste, fruit waste, tofu factory waste, and cow dung samples used in the study were identified and analyzed on the basis of the water content, volatile solids, C/N ratio, lignin content, and SRI and DRI values. In addition, an appropriate method for the further processing of unstable organic waste samples was determined. Organic waste samples were collected from nine places. Results revealed that the tofu factory waste samples exhibit the highest SRI and DRI values of 13.3995 mgO₂g^-1OM^-1h^-1 and 148.3747 mgO₂g^-1OM^-1h^-1 respectively. The composting results for tofu factory waste samples and cow dung with coconut shells as the bulking agent for 14 days revealed that the highest percentage of SRI decrease for tofu factory waste was 99.94% on the 3rd day of composting. On the other hand, the highest percentage of SRI decrease for the cow dung samples is 99.17% on the 7th day of composting.