Reproducible Multicriteria Reanalysis of a Four-Criterion UASB-Oriented Source Matrix for WWTP Biogas-Recovery Prioritization

This study performs a computationally reproducible multicriteria reanalysis of a four-criterion, UASB-oriented source matrix reported in a 2015 MSc dissertation. Two author-generated numerical scenarios, each containing six WWTP alternatives, are treated as constructed cases rather than verified operating-plant data. The retained criteria are UASB presence, a source-defined flow variable with an unresolved physical unit, CH4 concentration, and H2S concentration. Source-rule coding was rechecked, continuous values were ranked with TOPSIS and a weighted sum model (WSM), and sensitivity was examined through threshold perturbation, criterion-weight variation, and an explicit flow-variable test. Four coding inconsistencies were corrected. Under equal weights, WWTP6 ranked first in Case 1 and WWTP1 in Case 2, with 93.3% TOPSIS–WSM pairwise agreement in both cases. Multiplying or dividing the complete flow column by 24 left TOPSIS and WSM scores and ranks unchanged to numerical precision; removing flow preserved the first-ranked alternative in both scenarios but changed some intermediate positions. The results characterize only the documented four-criterion, UASB-oriented matrix and do not estimate absolute gas production, energy output, or economic feasibility.