Laboratory-Scale Physicochemical Simulation of Palm Oil Mill Final Effluent: Water Quality Analysis and Synthetic...

This study presents a systematic and reproducible methodology for developing synthetic wastewater that mimics the bulk physicochemical characteristics of palm oil mill final effluent (SWM-POME_FE) at laboratory scale. The framework was established through four sequential phases: (1) physicochemical characterization of real POME_FE (R-POME_FE), (2) dose-response analysis of selected media, (3) iterative formulation of SWM-POME_FE, and (4) stability and statistical validation. R-POME_FE was characterized across 10 sampling events to establish baseline conditions for key parameters. Dose-response analyses of glucose, lignin, surfactant, unrefined red palm oil, and NH₄Cl were conducted to reproduce COD, BOD₅, color, O&G, and NH₃-N contributions. Three progressively refined formulations were developed through iterative adjustments, demonstrating strong agreement between experimental results (Exp-R) and calibrated predictions (Cal-P), with deviations ranging from 0.3% to 6.3%. Statistical similarity analysis of the final SWM-POME_FE formulation showed that NH₃-N, O&G, color, and turbidity closely matched the distribution of the R-POME_FE dataset, with mean values falling within the 95% confidence interval, interquartile range, and ±10% tolerance band. These parameters also exhibited very small standardized deviations (|z| ≤ 0.2), indicating negligible differences relative to the natural variability of the field measurements. TSS met all criteria except the interquartile range (z = 0.76). In contrast, COD and BOD₅ fell outside the central distribution metrics but remained within the observed field range (z = 1.03 and 1.52, respectively). Although formal equivalence testing using the two one-sided tests procedure did not demonstrate strict equivalence, this was attributed to the large natural variability of the field measurements. Stability assessments further confirmed the robustness of the formulation, with < 5% variation during the 5-day short-term test and only minor reductions after 3-month storage, indicating that SWM-POME_FE provides a stable physicochemical surrogate for controlled laboratory studies.