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ABSTRACT
The influence of heavy metal contamination by iron and copper on the efficiency of activated sludge systems in removing nitrite, nitrate, and organic nitrogen was investigated. Wastewater was collected from a household disposal point. Experiments were conducted using two activated sludge systems, each containing 300 mL of wastewater. One system served as a control, while the other was treated with 20 mL of both 5 mg/L copper and iron solutions. Concentrations of nitrite, nitrate, and nitrogen were measured after 24 and 48 hours of detention, and removal efficiency was calculated. Physicochemical parameters including temperature (T), pH, total dissolved solids (TDS), electrical conductivity (EC), and oxidation-reduction potential (ORP) were also recorded. The removal efficiency of nitrite in wastewater was 5.9% and 80% after 24 and 48 hours, respectively, while wastewater treated with iron and copper exhibited higher removal efficiencies of 89.9% and 99.5% at 24 and 48 hours, respectively. Nitrate removal efficiency in wastewater was 70% and 73.3% after 24 and 48 hours, while the presence of iron and copper resulted in reduced nitrate removal efficiencies of -28% and 40.3% at 24 and 48 hours, respectively. Organic nitrogen removal efficiency in wastewater was 34.2% and 37.9% after 24 and 48 hours, while wastewater treated with iron and copper had lower organic nitrogen removal efficiencies of 13.3% and 19.6% at 24 and 48 hours, respectively. Physicochemical analysis results varied as follows: T from 28.55 °C ± 0.07 (wastewater with iron and copper at 24 hours) to 28.95 °C ± 0.07 (wastewater alone at 48 hours); pH from 5.62 ± 0.11 (wastewater with iron and copper at 48 hours) to 7.47 ± 0.08 (wastewater alone at 48 hours); EC from 571 ± 4.24 µS/cm (wastewater alone at 48 hours) to 696.5 ± 0.70 µS/cm (wastewater with iron and copper at 24 hours); TDS from 285.5 ± 2.12 ppm (wastewater alone at 48 hours) to 351 ± 4.24 ppm (wastewater with iron and copper at 24 hours); and ORP from -201 ± 21.21 mV (wastewater alone at 24 hours) to 256 ± 7.07 mV (wastewater with iron and copper at 48 hours). This study demonstrates that copper and iron pollution in wastewater negatively impacts removal efficiency in activated sludge system
