Effects of raw and treated olive mill wastewater (OMW) by coagulation-flocculation, on the germination and the growth of three plant species (wheat, white beans, lettuce)

Olive mill wastewater (OMW) constitutes a grand environmental issue for olive oil producing countries. It produces a large amount of organic matter, which is difficult to degrade, in particular phenolic compounds which are responsible for the phytotoxic effect. The aim of this research is to determine the potential COD and phenolic compounds removal of OMW treated by coagulation-flocculation with lime as coagulant and to evaluate the effects of raw and treated OMW on the germination and the growth of three plant species (wheat (Triticum turgidum L. var Durum), lettuce (Lactuca sativa varcrispa) and White bean (Phaseolus vulgaris L.). This treatment induced a high removal at a dose of 30g/L of lime by 40% and 97% respectively. The raw OMW showed an inhibitory effect on the germination and the growth of the three species. However, the three OMW dilutions (50%, 25% and 12.5%) stimulated the germination and the growth of wheat and white bean. The germination tests with OMW treated with lime and diluted at different concentrations present the best medium for growth of the three plants and the germination rate can reach 100%.