A study on olive oil mill wastewater management in Turkey: A questionnaire and experimental approach

The purpose of this study is to provide profound information about olive oil mill wastewater production in Turkey and to evaluate and optimize the treatment of olive oil mill wastewater (OOMW) by using slow rate land treatment system. Within the scope of the study, about 150 olive oil industries located in the west and south of Turkey were examined by means of a questionnaire survey. The results showed that high percentage of producers in Turkey use three-phase centrifugation generating high amount of wastewater. The use of large evaporation ponds is the common treatment technology for the "reduction" of the wastewater. For the experimental part of the study, nine 65-liter PVC reactors were constructed and operated outside the laboratory. Reactors containing 55 kg of sandy-loam soil were planted by Reed (phragmites) and Alfalfa (alphalpha sp.) species and irrigated with olive oil mill wastewater having the same organic loading but different hydraulic loading rate. BOD5 loading rate was 500 kg BOD5/ha day and hydraulic loading rates were 2, 4, 8 and 12.5 m/year. Hydraulic loading is later fixed to 4 m/year and organic loading is changed to 125,250 and 500 kg BOD5/ha day during the second year. The results of the experiments indicated that COD removal rates were initially high in reactors with plants compared to control reactor without plant. However, the rates decreased in time due to the inhibition observed in the treatment capacity of the combined system. (C) 2011 Elsevier B.V. All rights reserved.