Document Type : Research Paper
Authors
1
Department of Water Engineering and Environment, the Caspian Sea Basin Research Center, University of Guilan, Rasht, Iran
2
Department of Water Engineering and Environment, the Caspian Sea Basin Research Center, University of Guilan, Rasht, Iran; & Department of Chemical Engineering, Faculty of Engineering, University of Guilan, Rasht, Iran
10.22124/cjes.2026.9878
Abstract
This study aims to optimize the Fenton treatment of real citrus-processing wastewater (CPWW) using response surface methodology (RSM) and to develop a techno-economic assessment for a treatment capacity of 200 m³ day-1. The experimental design, analysis of variance, and response-surface plots were performed using Design-Expert v.12 software. Under the optimal conditions—2,500 mg L-1 H₂O₂, 750 mg L-1 FeSO₄, pH 3, and a reaction time of 90 min—a maximum chemical oxygen demand (COD) removal of 38.2% was achieved. The relatively moderate COD removal obtained in the present study should be interpreted in the context of the real wastewater matrix, considering the possible presence of recalcitrant citrus-derived compounds, radical scavengers, and constituents capable of complexing iron. For a full-scale plant with a capacity of 66,000 m³ year-1, the estimated treatment cost was $7.563 m-³, equivalent to $5.04 per kilogram of COD removed. Overall, the estimated cost lies between the higher reported costs of photo-Fenton treatment and the lower reported costs of biological-treatment technologies. Operational expenditures (OPEX) accounted for 98% of total costs, with hydrogen peroxide alone contributing 89.9% of annual OPEX. Sensitivity analysis revealed reagent costs as the most influential parameter, where a ±20% fluctuation led to a ±18.82% variation in total costs, highlighting the vulnerability of Fenton economics to chemical supply markets. Interest rate variations similarly impacted annualized capital expenditures (CAPEX), with ±20% fluctuations resulting in ±19.6% changes. This study provides a transparent cost model, identifies reagent consumption as the primary economic bottleneck, and highlights opportunities to integrate Fenton oxidation with pre- and/or post-treatment processes to reduce oxidant demand and improve COD removal beyond that achievable by stand-alone Fenton treatment. This study establishes a scalable techno-economic framework for Fenton oxidation of CPWW; it highlights limitations in pollutant removal efficiency and identifies hydrogen peroxide as the primary cost driver, which significantly increases sensitivity to market fluctuations.
Keywords
)