In Journal of environmental management
Averting nutrient volatilisation in thermal treatment of organic waste is a challenging task. The dynamics of ammonia volatilisation and the role of additives in preventing the losses of nutrients in thermal digestion of food waste (FW) were explored. The experimental trials were performed in a convective dehydrator at different combinations of temperatures and airflow velocities. The study dictated that ammonia volatilisation rate increased with increase in temperature and airflow velocity. The losses reached to its peak during the initial drying period and then gradually declined in the falling rate period. An artificial intelligence-based random forest model was explored to precisely predict the ammonia losses during the drying process. The SEM-EDX images confirmed enhanced N (2.25%) in the alum treated end product compared to blank (N - 1.8%) and thus reveals alum induced mineralization of nutrients. Higher intensities of the N containing compounds peaks observed in FTIR spectra also supported the mineralization of nitrogen. XRD analysis indicated formation of stable ammonium compounds in the sample digested with alum. Cost benefit analysis of the alum aided digestion revealed that it enhances the nutrient retention and overall cost of N in the end product by ₹626/tonne. The study revealed high potential of alum in reducing the ammonia volatilisation and enhancing the agronomical value of nutrients in the thermal digestion process.
Kumar Nitin, Gedam Pratik, Gupta Sunil Kumar
Additives, Ammonia volatilisation, Food waste, Nutrient retention, Random forest, Thermal digestion