Effect of copper and iron pollution on efficiency of activated sludge system to remove nitrogen from wastewater

Abstract

The pollution of waste water with heavy metals can result in the inefficiency of wastewater treatment systems. The effect of heavy metals pollution on nitrite, nitrate and organic nitrogen removal efficiency of activated sludge system was evaluated using iron and copper. Blackwater was collected from a residential disposal point. Experiments were conducted using two activated sludge systems with 300 mL of wastewater. One served as control while the other other treatment  received 20 mL of 5 mg/L of iron and copper solutions. The concentration of nitrite, nitrate and nitrogen was analyzed after 24 hrs and 48 hrs detention time and removal efficiency was calculated. Physicochemical parameters were measured. The removal efficiency of nitrite was 5.9% and 80% after 24 hrs and 48 hrs respectively while the treatment system with added iron and copper had higher removal efficiency of 89.9% and 99.5% after 24 and 48 hours respectively. The nitrate removal efficiency from  Blackwater was 70% and 73.3% after 24 and 48 hours respectively while  Blackwater with iron and copper added  had low nitrate removal efficiency of -28% and 40.3% after 24 hrs and 48 hrs respectively. The organic nitrogen removal efficiency of the Blackwater was 34.2% and 37.9% after 24 hrs and 48 hrs respectively while that of Blackwater with iron and copper added had removal efficiency of 13.3% and 19.6% after 24 hrs and 48 hrs respectively. This study demonstrates that copper and iron pollution in wastewater negatively impacts nitrogen removal efficiency in activated sludge systems.