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Removal the pollutants of oil mill wastewater by coagulation–flocculation in order to protect the aquatic environment: Sludge characterization

Djamel Temim, Saadia Guergazi, Sarah Goudjil, and Leila Youcef

Research Laboratory in Subterranean and Surface Hydraulics, Biskra University, Biskra, Algeria



Received: 19 January 2022  Accepted: 6 June 2022


The industrial sector of olive oil production generates large quantities of liquid effluents called oil mill wastewaters (OMW). These acidic OMW are very loaded with organic matter and polyphenols in the form of humic acid, which is released into the natural environment without any prior treatment. This will seriously harm the quality of the water and pose a major ecological problem. Therefore, the objective of our work is to test the performance of the coagulation–flocculation process by aluminium sulphate (AS) in the elimination of certain parameter characteristics of OMW. These are humic acid (HA), chemical oxygen demand (COD) and turbidity. Different parameters were taken into consideration, such as the effect of AS doses, pH and the variation of powdered activated carbon (PAC) used as an aid coagulant. The X-ray diffraction (XRD), Fourier transform infrared (FTIR) and the scanning electron microscopy (SEM) characterized the solid phase of OMW before treatment and the sludge of the optimal dose of the coagulant. After dilution of the OMW to 1/100, our results clearly showed that treatment reduced the polluting load of water by 67.31 and 71.15%, respectively, for HA and COD, and the turbidity is 82.45%. The pH of the optimal treatment is in acidic medium less than or equal to 5. The use of PAC has led to a remarkable improvement in the removal yields, which exceeds 80% for both HA and COD.

Keywords: OMW; Sludge characterization; Coagulation/flocculation; Humic acid; COD and turbidity removal; Coagulation/adsorption

Full paper is available at

DOI: 10.1007/s11696-022-02324-8


Chemical Papers 76 (11) 6891–6902 (2022)

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