Material Recovery Trade-Offs Under Inverter-Controlled Operation of a Full-Scale Municipal Solid Waste Mechanical Treatment Line

Mechanical treatment recovers combustible and recyclable fractions from mixed municipal solid waste (MSW), but full-scale performance is sensitive to front-end operation, line loading, and feedstock heterogeneity. This study examined material recovery trade-offs at a municipal mechanical treatment facility in Satun, Thailand. Four inverter-controlled regimes were assessed by adjusting the bag opener and trommel motor frequencies, giving measured line throughputs of 14.75, 13.45, 8.03, and 6.54 t·h−1. Output was classified as refuse-derived fuel (RDF), residual waste, recyclables, and bulky/loss material, with composition-based indicators of stream cleanliness and leakage. Each regime was a single short trial on waste from a different collection vehicle, without replication or input homogenization; no statistical comparison is possible, and results are reported as preliminary observations rather than isolated effects of inverter frequency. RDF yield fell from 42.06% of input at the highest throughput to 18.12% at the lowest, whereas recyclable recovery peaked at 4.95% under an intermediate regime that also returned the highest gross revenue. Residual-disposal methane generation potential was 7.78% higher under the lowest-throughput regime than under business-as-usual. Three trade-offs emerged: throughput against selectivity, RDF quantity against cleanliness, and recovery against leakage. The findings help operators select front-end settings on multi-criteria indicators rather than throughput alone.