Optimized Microwave-Assisted Fenton Oxidation for Simultaneous Reduction of COD, BOD, and Emerging Organic Pollutants in Mixed Industrial Wastewater
Year: 2026
Type: preprint
Abstract: Industrial and pharmaceutical wastewater discharged in Nigerian urban centres carries high chemical and biochemical oxygen demand alongside emerging organic pollutants, including phthalate esters and butylated-hydroxytoluene (BHT) oxidation products, that conventional biological treatment cannot reliably remove. This study evaluated a microwave-assisted Fenton (MW-Fenton) oxidation process for the simultaneous reduction of chemical oxygen demand (COD), biochemical oxygen demand (BOD) and five identified emerging organic pollutants in real mixed wastewater collected from multiple point sources across pharmaceutical manufacturing and clinical facilities in Kaduna State, Nigeria. Wastewater was acidified to pH 2.5–3.5, treated with 1.70 x 10 − 4 M FeSO4 and 5% v/v H 2 O 2 , irradiated at 700 W for 10–30 min, and neutralised to pH 8-8.5 to precipitate iron as Fe(OH) 3 flocs before filtration and GC-MS profiling. Across five representative samples, COD fell by 40–74% and BOD by up to 85%, with the greatest reductions recorded in the RO/EDI/softener and Simulated 1 effluents. GC-MS profiling of five identified pollutants (a BHT oxidation marker, two BHT-derived phenolic degradation products, bis(2-ethylhexyl) phthalate (DEHP), and a branched phthalic acid ester) showed no detectable residual concentration, i.e. below the GC-MS detection threshold, in the great majority of sample-pollutant combinations, with only two exceptions: the BHT oxidation marker was reduced by 79.11% rather than to non-detect in the Metro Suspension sample, and DEHP showed a small net increase (-4.54%) in the RO/EDI/softener sample, plausibly attributable to leaching from residual treatment-train plastic components rather than treatment failure. These results indicate that MW-Fenton oxidation, optimised for a strongly acidic reaction pH and combined microwave/hydrogen-peroxide dosing, can simultaneously reduce bulk organic loading (COD/BOD) and target-specific endocrine-disrupting pollutants in real, compositionally heterogeneous industrial wastewater, offering a candidate pre-treatment option for resource-limited settings where pharmaceutical and mixed-industrial effluent is discharged with minimal prior treatment.
Source: Research Square
Author: Mathew Gideon
Language: English
Subfield: Water Science and Technology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7204552104