Abstract
This study compared a control UASB reactor (R1) with an optimized reactor (R2) receiving mineral and organic additives for the treatment of hospital wastewater from the University Clinics of Kinshasa. Granules were characterized by Fourier-transform infrared (FTIR) spectroscopy, and relationships between spectral features and treatment indicators were explored using Pearson correlations, multiple linear regression, and one-way ANOVA. Compared with R1, R2 granules showed higher relative intensities in bands assigned to O–H/N–H, C–H, Amide I, Amide II, COO⁻, C–O–C, carbonate, and Fe–O/silicate groups. The descriptive data also showed lower residual COD (42 ± 4 vs 210 ± 15 mg/L), BOD₅ (31 ± 3 vs 120 ± 10 mg/L), and TSS (15 ± 2 vs 95 ± 8 mg/L) in R2, together with higher Fe (91 ± 3% vs 60 ± 6%) and Cu retention (96 ± 2% vs 55 ± 5%). FTIR intensities were strongly associated with residual organic-pollution indicators and metal retention, and the reported regression model identified amide-and carbonate-related bands as predictors of COD. The reported ANOVA results indicated differences between R1 and R2 (p < 0.001). These findings support an association between enhanced bio-mineral granule structuring and improved reactor performance. However, the manuscript does not report the number of independent replicates, exact additive doses, ANOVA degrees of freedom, or regression diagnostics; these elements should be provided before the inferential results are considered fully reproducible.
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