Performance Evaluation of Hybrid Septic Tank and Aerated Lagoon Process Efficiency for Landfill Leachate Treatment

In this research, landfill leachate treatment in Karaj city was investigated by a linked septic tank and aerated lagoon. At first, characteristics of the leachate were determined. Then a pilot plant with anaerobic-aerobic (Septic tank and Aerated lagoon) parts was installed and started. Results showed that Chemical Oxygen Demand (COD) removal efficiency for septic tank and subsequently to lagoon for influent COD of 19537 mg/L, were 8401 and 432 mg/L, respectively. The septic tank and aerated lagoon also operated with different flow rates and the best results for septic tank and aerated lagoon obtained in 23.6 L/day and 9.3 L/day respectively with maximum COD removal efficiency of 91.2%. According to the obtained results, the hybrid system had 90% COD removal efficiency. Therefore, leachate COD loading could be effectively removed in this system.