FUNGAL BIOTREATMENT OF OLIVE MILL WASTE WATER

Abstract

The current study was aim to remediate olive mill waste water (OMWW) to reduce its phenol content and Chemical Oxygen Demand (COD) using fungal isolates. OMWW samples were drawn from the outlet of olive presser at Agriculture Research center, Egypt and characterized. Inoculating 25% diluted waste sample on Potato dextrose agar plates, incubated for 2 weeks at 25oC, resulted in 8 fungal isolates, of which isolate 5 was selected based on its capabilities to degrade phenol and reduce COD, compared to the rest of the obtained isolates. Comparison was conducted between the selected isolate and the fungus Pleurotus columbinus as a reference to test their potencies to degrade phenol and reduce COD in OMWW at concentrations from 100 to 10% over 4 weeks and results showed low degradability and weak tolerance of the two organisms at concentrations from 50 to 100%, while at 40, 30, 20 and 10%, phenol degradation and COD reduction over the 4 weeks treatment were more obvious. At all concentrations P. columbinus showed better competency for phenol degradation and COD reduction than isolate 5. Decolorization and growth of the two organisms were investigated in OMWW at 40 to 10% concentrations. P. columbinus, again, showed better competency over isolate 5 where it 79 and 49% of the color were removed after 4 weeks by P. columbinus and isolate 5, respectively. Total carbohydrate was also determined in the treated OMWW over 4 weeks and results showed it decreased from 6.05 to 5.2g/L in 40% OMWW and from 4.27 to 3.6 g/L in 30% OMWW, while it increased from 3.1 to 4.37g/L in 20% OMWW and from 1.46 to 3.9 g/L in 10% OMWW. Finally, the presence of indol acetic acid and gibberellins in 20 and 10% OMWW was tested as affect by the treatment with P. columbinus over the period of 4 weeks.Results showed that, after 4 weeks, IAA content decreased from 29.4 to 23.25 µg/ml in 20% OMWW, and slightly from 15.6 to 13,15 µg/ml in 10% OMWW. For gibberellins, the change after 4 weeks in 20% OMWW was not significant, that it decreased from 1.36 to 1.25mg, while it increased from 0.667 to 1.58 mg/ml in 10% waste in the same period. It can be concluded that remediating OMWW with P. columbinus can achieve a better results and the treated waste may be suitable for irrigation of crops.