Spectral Characterization and Indexing Methods for the Quality Assessment of Municipal Solid Waste Compost Prepared Using Novel Bacterial Consortia

Composting is one of the integral components of the global circular bio-economy platform. However, traditional composting contains major limitations, including its longer time requirement and the formation of odour. Therefore, the inoculation of efficient novel bacterial consortia for compost process modification is a global concern. Furthermore, the assessment of compost quality is crucial because immature compost can cause phytotoxicity, disrupt soil structure, and damage the natural ecological balance when used in agriculture. Conversely, there is no universally applicable procedure to determine compost quality, maturity, and stability. This study focuses on assessing the quality of compost produced by five novel microbial consortia using indexing and spectroscopic methods. Clean Index (CI), Fertilizing Index (FI), Germination Index (GI) and Vigor Index (VI) were used as indexing methods to assess the phytotoxicity and compost quality. Scanning Electron Microscopy (SEM), X Ray Diffraction spectroscopy (XRD) and Energy Dispersive X-ray Spectroscopy (EDS) techniques were used for spectroscopic analysis of compost microstructure. The results revealed that out of all compost samples (including the control), the compost made by Consortium 5 (C5) recorded a significantly greater (p<0.05) GI, VI, FI and CI compared to the control and other treatments. Further, the GI value of C5 was recorded as 110.2 ± 2.2 %, demonstrating the possible usage of C5 compost as a phytonutrient soil amendment. Importantly, SEM, XRD and EDS spectrograms also confirmed the rapid waste degradation pattern and elemental composition alteration by the C5 consortium. Consequently, the compost by the C5 consortium was categorized into the compost quality “A” category, whereas the control compost belonged to the compost quality “D” category. In contrast, the findings of the present study confirm that the potential applicability of a prepared novel bacetrail consortium as a rapid, greener waste management approach in the circular bio-economy.