Using powdered activated carbon to enhance atrazine removal in an anoxic/oxic (A/O) process

Laboratory-scale experiments based on an anoxic/oxic (A/O) wastewater treatment process were conducted to investigate the effects of an spill of the emergent atrazine pollutant on the operation of wastewater treatment plant, as well as the feasibility of using powdered activated carbon (PAC) to improve the performance of the treatment system after the accident. Atrazine was added with a concentration varying from 2.5 to 20 mg/L at different experimental stages. The results showed that the performance of the A/O system, in terms of chemical oxygen demand (COD) and ammonia nitrogen (Formula presented.) removal, was negatively affected by the presence of atrazine. However, the system could recover a more than 80% of COD and 70% of (Formula presented.) -N removal within 6 d under an atrazine concentration of less than 10 mg/L. A 20 mg/L atrazine concentration showed irreversible effects on the treatment performance. PAC addition was found to be able to greatly improve the performance of the system at the atrazine concentration of 20 mg/L, as indicated by the oxygen uptake rate of microorganisms. The activity of the bacteria was proportional to the PAC dosage under experimental conditions, and a 300 mg/L of PAC dose was recommended.