Phytoremediation of organics and metals from Olive Mill Wastewater

The cultivation and processing of olives for olive oil production are among the most important industries in Palestine. The olive oil extraction process produces huge amounts of liquid waste called Olive Mill Wastewater (OMWW). Disposal of OMWW is a major environmental issue. In Palestine OMWW is being disposed of into the wadies. The present work aimed at studying the possibility of using the phytoremediation to remove polyphenol and heavy metals ( Fe, Cu, Zn, and Ni) from OMWW. Four groups of pots were cultivated by barley (Hordeum vulgare L) seeds in similar way like seeding in fields (approximately one seed per cm) and watered by OMWW (Zebar 100%), diluted OMWW (Zebar 50%), fresh water (FW) and prepared solution (SL) that has the same concentration of polyphenol and heavy metals ( Fe, Cu, Zn, and Ni) in OMWW. The concentration of polyphenol and heavy metals in OMWW and the soil before planting was measured. A week after germination, one pot from each group were taken, the soil were separated from the roots of barley and mixed to take a sample for analysis to measure the concentration of polyphenol and metals, these analyses were repeated for the rest of the pots weekly. Flame atomic absorption was used for metals analysis. Total phenol content of each OMWW samples was analyzed according to Folin-Ciocalteau colorimetry method. Eight days after planting, the seeds were germinated in three groups of pots (Zebar 100%, Zebar 50%, FW), while the fourth (SL) was not germinated at all. In the first group (Zebar 100%), the barely plants were shorter than those irrigated with diluted OMWW and fresh water, and the number of plants was less. It is noticed that the concentration of polyphenol, Fe and Zn decreased during the experiment, while there were no significant reduction in concentrations of Cu and Ni. The mass of polyphenol and Fe absorbed by barley plants were the most significant. Uptake ratio of polyphenol was 0.19 in the pots which were irrigated with Zebar 100% at the end of experiment. While it was 0.31 and 0.26 in the samples which were irrigated with Zebar 50% and fresh water respectively. It is noticed that the absorption ratio of Fe was the most significant among the other metals, it was 0.27, 0.42 and 0.49 in samples which were irrigated with Zebar 100%, Zebar 50% and fresh water respectively. The uptake of polyphenol and metals (Fe and Zn) follow first order reaction with k value (day-1) 0.006, 0.012 and 0.003 for polyphenol, Fe and Zn respectively, and high R2 value (nearly 0.98) in the pots which were irrigated with diluted OMWW (Zebar 50%).