Combined anaerobic and aerobic biological co-treatment of olive mill wastewater and municipal wastewater

This project investigated the efficiency of the combined anaerobic - aerobic biological cotreatment of olive mill wastewater and primary municipal wastewater. A lab-scale (6,5L) Upflow Anaerobic Sludge Bed (UASB) reactor received a mixture of two-phase centrifugal olive mill wastewater and primary municipal wastewater at a loading rate ranging between 3 and 7 KgCOD/m(3)d. The input COD concentration ranged between 1800 and 4400 mg/L. The anaerobic reactor operated at mesophilic conditions (35 degrees C). The effluent organic load was between 400 and 600 mgCOD/L, while at the same time SS removal efficiency varied between 75 - 95%. Biogas production ranged between 5L/d and 12L/d, corresponding to around 3 to 6 L/gCOD removed. The anaerobic reactor effluent was further treated in a labscale activated sludge treatment plant. Aerobic treatment resulted in an effluent that reduced the organic load even further to 85mgCOD/L - 175mgCOD/L. This treatment method showed that it is possible to treat olive mill wastewater in a municipal wastewater treatment plant by a high-rate anaerobic reactor located between the primary clarifier and the aeration tank.