Evaluation of biological landfill leachate treatment incorporating struvite precipitation and powdered activated carbon addition

Direct application of aerobic biodegradation for leachate treatment is not feasible due to high concentrations of nitrogen and chemical oxygen demand. Several potential leachate treatment schemes incorporating struvite precipitation as pretreatment and two types of activated sludge processes (conventional activated sludge and batch decant reactor (intermittent cycle extended aeration system [ICEAS process]) with and without addition of powdered activated carbon (PAC) were evaluated in this study. The hydraulic retention times (HRT) of 6 h and 12 h were applied in the biological stages of each process. Treatment schemes incorporating PAC addition showed acceptable results. In the conventional activated sludge process, total chemical oxygen demand (TCOD), soluble chemical oxygen demand (SCOD), NH3, and P removal rates were 87, 84, 98.3, and 94%, respectively, with HRT of 6 h and 95.8, 95.1, 99.1, and 98.7% with HRT of 12 h. For the ICEAS process, removal rates were 89.3, 87.9, 98.2, and 94% with HRT of 6 h and 95.8, 95, 99.2, and 98.7% with HRT of 12 h. On the basis of these results, it can be concluded that struvite precipitation, followed by activated sludge process with PAC addition, can be a strong alternative leachate treatment, achieving the standards set for effluent discharges to receiving waters.