Exploring the feasibility of thermal digestion process: A novel technique, for the rapid treatment and reuse of solid organic waste as organic fertilizer

Abstract The study developed a holistic approach based on the thermal digestion (TD) technique for the rapid conversion of solid organic waste (SOW) into nutrient-rich organic fertilizer. The effect of digestion temperatures (110oC–170 °C) on the weight reduction from the SOW and the availability of the nutrients were thoroughly investigated. The potential weight reduction of 75.2% was achieved at a temperature of 150 °C for 135 min, as illustrated by response surface methodology (RSM). Scanning electron microscope (SEM) study was carried out to analyze the changes into surface morphology of the sample before and after the digestion. Fourier transform infrared (FTIR) analysis was conducted to study the mineralization process. Thermogravimetric-Differential thermal analysis (TG-DTA) was conducted to study the thermal decomposition behavior of the untreated and digested SOW. The digested SOW resulted high nutrient-rich end product (N-2.08 ± 0.01%, P-0.42 ± 0.00%, & K-1.65 ± 0.06%), which have potential to be used as organic fertilizer. Fertilizing potential of the digested SOW complied with the delineated norms of the organic fertilizer given by the Fertilizer Association of India (2019). Maturity and phytotoxicity of the digested SOW were explored on the basis of C:N ratio (18.07 ± 0.17), humification index (3.43 ± 0.02), heavy metals content, as well as through seed germination index (>90%). The proposed technology may lead to the paradigm shift in waste management and provides an efficient alternative for the recycling of nutrients.