Treatment of Wastewaters Olive Mill by Electrocoagulation and Biological Process

Abstract

Olive mill wastewaters (OMWW) cause a recurrent environmental pollution problem. Treatment and reuse of olive mill wastewater (OMWW) presents significant challenges both due to the nature of olive oil production (seasonal and small scale) and due to the characteristics of the wastewater (high chemical oxygen demand (COD) and high phenolic content in the organic fraction of OMWW principally responsible for the phytotoxicity and microbial growth inhibitory effects of the effluent). In the present work the combined pretreatment of actual olive mill wastewaters by electrocoagulation and coagulation with natural organic coagulant, such as TNN and Kim 2212, and the biological purification, was investigated. Tests were conducted with raw OMWW and diluted with tap water at pH neuter adjusted by adding lime coagulant with chemical oxygen demand (COD) contents of 178 g d'O2.l-1, total suspended solids (TSS) of 6,4 g/L, Conductivity (mS.cm-1) of 29, pH of 4,8 and turbidity of 50 NTK. The optimum removal of COD, turbidity and total polyphenolic was respectively 38,39 % , 74,45 % and 60%. This results was obtained with TNN coagulation at pH (7) and 20 mg/l of the coagulant . The maximum organic matter removals by electrocoagulation (56.76%) processes was achieved after 90 min, by using 15V/m² voltage kept constant for each run at initial pH of the OMWW (4,4). Olive mill wastewater (OMWW) was then treated aerobically with fungi. The results show that the fungus is capable of reducing chemical oxygen demand 68% and 75% for the diluted OMWW at 50 % treated by lime and lime/KIM 2120 respectively, after only 5 days of growth. Neutral pH seems supported aerobic treatment.