TITLE:
Analysis of Pollutant Loads in the Wastewater of a Hydrocarbon Industry and Evaluation of the Effectiveness of Their Treatment
AUTHORS:
Haroun Ali Adannou, Haroun Héloua, Ganon Francois, Salwa Fadoul Ahmat, Aboubakar Ali Mahamat, Hassane Souleymane Mahamat, Ahmed Mohammed Mohagir
KEYWORDS:
Industrial Wastewater, Hydrocarbons, Heavy Metals, Physicochemical Treatment, Biological Treatment, Treatment Efficiency
JOURNAL NAME:
Open Journal of Inorganic Chemistry,
Vol.16 No.1,
January
15,
2026
ABSTRACT: This study evaluates the effectiveness of the wastewater treatment system at a hydrocarbon refinery in Chad. Pollutant loads, including Chemical Oxygen Demand (COD), 5-day Biochemical Oxygen Demand (BOD5), total hydrocarbons, heavy metals (As, Cr, Pb), phenols, and sulfides, were measured before and after treatment. Samples were analyzed using standard methods at the industry laboratory and the national water laboratory. Before treatment, the wastewater exhibited extreme pollution: COD up to 3000 mg/L, BOD5 up to 1925 mg/L, and hydrocarbons up to 1000 mg/L. The combined physicochemical and biological treatment demonstrated high effectiveness, with removal rates exceeding 95% for both COD and BOD5, and a reduction of hydrocarbons to less than 10 mg/L. The pH of the treated effluent was stable (6.5 - 8.5). However, residual concentrations of arsenic and chromium occasionally exceeding local standards were detected, indicating the need for targeted tertiary treatment. The study concludes that the system is generally effective but recommends enhanced monitoring and optimization of heavy metal removal.