Applying solar distillation for the sustainable management of olive mill wastewater

Olive mill wastewater (OMWW) is a major by-product of olive oil production industry. Its chemical characteristics (high concentrations of COD and TSS, low pH value, existence of total phenols at the range of some ppm) does not allow its efficient treatment using conventional physiochemical or biological wastewater treatment methods. On the other hand, an important number of compounds with bioactive properties have been detected in OMWW increasing the scientific and economical interest for their recovery. In the current study, lab experiments were initially conducted using conventional distillation to study the role of temperature and initial OMWW characteristics to the composition of the distillate. Chromatographic analysis revealed the presence of different bioactive compounds in the distillates as well as the positive role of temperature’s increase on their recovery. A pilot-scale solar still system was afterwards constructed to investigate the simultaneous solar drying of OMWW and the recovery of bioactive compounds with antioxidant properties in the distillate. The system operated in different experimental cycles and the produced distillates and solid residues were analyzed for the presence of bioactive compounds and the energy content, respectively.