Anaerobic Treatability of Olive Oil Mill Wastewater

Abstract

A study was undertaken to evaluate the anaerobic treatability of different types of olive oil mill wastewater, including raw waste (concentrated or diluted) and pretreated waste containing soluble organics only. Anaerobic treatment of concentrated raw waste in draw and fill digesters operating at organic loading levels up to 4 kg COD/m1·d effected 68-74% mean BOD5 and 78-81% mean COD removals, while treatment of diluted raw waste in the same type digesters fed at a hydraulic detention time of 8 d and organic loading levels up to 3.7 kg COD/m3·d resulted in 83-84% mean BOD5 and 75-77% mean COD removals. Anaerobic treatment of the soluble organics contained in mill wastewater in draw and fill digesters operating under simulated steady state conditions at hydraulic detention times 8-20 d and an organic loading level of 0.8 kg COD/m3·d achieved 72-88% mean BOD5 and 56-70% mean COD removals. The maximum attainable soluble organics removal was found in the range 77-79% for soluble COD and 92-95% for soluble BOD5.