Optimization of trommel screen performance in municipal solid waste landfill mining and legacy waste characterization

Abstract

The disposal of solid waste in dumpsites is getting increased in developing countries due to rapid urbanization. Biomining is an innovative idea to recover valuable resources from legacy waste and usable land from old dumpsites. Various mechanical equipments are employed in the biomining process, out of which the trommel screen plays a major role in sieving the legacy waste into different fractions. Optimization of trommel screen performance in the biomining process is carried out in this project. Feasible operating parameters such as the feed rate of the trommel screen 1 (100 mm) and trommel screen 2 (4 mm) and moisture content of legacy waste were optimized in the Rajapalayam biomining site, Tamil Nadu, India. The characteristics of legacy waste in three different biomining sites, namely, Rajapalayam, Srivilliputhur, and Sivakasi, were analyzed. Results indicate that 9 and 2 m³ h^–1 feed rates show more separation efficiency for trommel 1 and 2, respectively. Changing the feed rates to the optimized values is also suggested to get better separating efficiency without compromising the purity and recovery of fractions. The recovery of the underflow fraction is maximum at a moisture content of 1.5% and 5.3% for trommel 1 and trommel 2, respectively. The trommel screen gets clogged for higher and lower values of moisture content so that the recovery of the underflow fraction gets affected. The refuse-derived fuel (RDF) characteristics meet the standard for reuse in cement kilns, and the bioearth characteristics are not suitable to be used as a soil amendment in its original form due to the unavailability of nutrients such as NPK and elevated C/N ratio.