Synergy of Charcoal-Cellulose Fibers for Enhanced COD and TSS Removal From Oily Industrial Wastewater: Experimental Assessment and Statistical Modeling.

This study evaluates a low-cost fiber medium composed of animal charcoal and tissue paper (AC-TP) as a bench-scale polishing approach for treating oily industrial wastewater from Makkah Power Plant. Thirty-six samples were collected over 6 months from three operational areas: the fuel unloading area (FUA), the fuel tank area (FTA), and the turbine unit area (TUA). The samples were analyzed for chemical oxygen demand (COD), total suspended solids (TSS), total dissolved solids (TDS), turbidity, and oil and grease. COD reduction was the primary indicator, while AC-TP-corrected filter-retained solids mass and filtration time were supporting indicators. Dose screening on FUA samples with AC:TP ratio of 1.0:0.5 was identified as the preliminary best-performing dosage based on COD reduction, with corrected filter-retained solids behavior and available filtration-time data used as supporting indicators. Applying this dosage to FUA, FTA, and TUA wastewater yielded COD removals of about 75%-82%, 79%, and 79.5%, respectively. Retained solids mass increased by 20%-55%, and filtration time decreased by up to ~60%. Statistical analyses using analysis of variance (ANOVA), paired t-tests, and COD-TSS/COD-filtration-time regressions confirmed the significance of these improvements. Scanning electron microscope (SEM) and X-ray diffraction (XRD) observations supported a tentative interpretation of coupled carbon-assisted organic removal and fiber-assisted physical retention.