DECOLOURIZATION AND REMOVAL OF PHENOL COMPOUNDS FROM OLIVE MILL WASTEWATER BY O-3/UV/NaBO3 AND PRE-TREATMENT

Abstract

Olive mill wastewater (OMW) generated by the olive oil extracting industry is a major pollutant, because of its high organic load and phytotoxic and antibacterial phenolic compounds which resist biological degradation. The aim of this study was to evaluate the feasibility of decolourization and removal of phenol and lignin in OMW by O-3/UV/NaBO3 and pre-treatment. In pre-treatment experiments, chemical coagulation experiments with lime and alum have been carried out. In the photolytic degradation experiments, the effect of NaBO3 dosage, times, pH, O-3, temperature and OMW concentration were determined to find suitable operating conditions for the best removal. At the end of this procedure, decreasing colour change intensity from 10.41 to 1.71 has been observed. The phenol concentration decreased from 300 mgL(-1) to 111 mgL(-1), the lignine concentration from 10.60 gL(-1) to 1.61 gL(-1) and the value of COD from 61000gL(-1) to 9.76gL(-1). From the experimental results, optimum values for the degradation of phenol and lignin were favorable at pH 9.0, colour degradation was observed in acidic conditions (pH<5.0 and pH>3.0). The optimum time and temperature for removal of colour, phenol and lignin were found to be 10h and 308K, respectively. In addition, the pseudo-first order model was applied and r(2) values were noted from 0.90 to 0.99. From these results, it can be said that this study proves the effectiveness of photolytic removal for highly concentrated organic pollutants present in OMW. Moreover, there is no study in the literature related to the use of O-3/UV/NaBO3 in OMW treatment and O-3/UV/NaBO3 may constitute an important step for further purification processes such as adsorption, membrane processes, etc.