Effect of oil mill wastewater processed by infiltration-percolation on the germination and growth of four plant species
The interest for environmental protection through an ecological management of olive waste has become currently a preoccupying element. The purpose of this study was to determine the feasibility of the use of oil mill wastewater treated with the infiltration - percolation technique through five different filters based on sea sand, agricultural soil and fly ash. The behavior of four plant species: radish (Raphanus sativus R.), turnip (Brassica rapa L.), tomato (Solanum lycopercium C.) and alfalfa (Medicago sativa L.) during germination (rate and average speed of seed germination) and growth (length of roots and stems, fresh weight and dry weight), have been highlighted in this paper. The effluents used have an acidic pH (5.9), an electrical conductivity of 26.6 (mS∙cm-1) and a suspended solids content of about 32.1 g∙L-1. They are heavily charged with organic material with a chemical oxygen demand (COD) content of 268 g∙L-1, the biological oxygen demand (BOD5) of 1.34 g∙L-1 and total phenols of the order of 2.66 g∙L-1. Adsorption tests have confirmed the effectiveness of these natural minerals in the reduction of phenolic compounds, COD and BOD5 contained in oil mill wastewater. However, we achieved complete inhibition of germination tested with raw oil mill wastewater for all species. We have noticed an increase of the germination process according to the dilution of the vegetable water. The results of the effect of vegetable treated on germination and emergence of the vegetative species studied has shown that filtrates whose percolation infiltration column is composed of a combination of ash and agricultural soils, presented the best results.