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Comparative study of the effect of temperature on two different
Ion Exchange operating modes for the removal of the major
contaminants in simulated pretreated olive mill wastewater
M. D. Víctor-Ortega1*, J. M. Ochando-Pulido1, S. Rodríguez-Vives and A. MartínezFérez1
1
Department of Chemical Engineering. University of Granada, Campus Fuentenueva,
s/N. 18071, Granada, Spain
*Presenting author contact: [email protected]
The control of liquid wastes from the olive oil industry is of major importance nowadays,
especially in the Mediterranean countries. Spain is the biggest olive oil producer
worldwide, followed by Italy, Greece and Turkey. Olive mill wastewater (OMW) is a
highly pollutant industrial effluent, which consists of olive-fruit extract water and water
added to the process. This effluent has very high chemical oxygen demand (COD) and
high concentration of organic compounds, such as phenolic compounds and tannins. In
addition, inorganic compounds such as chloride, sulfate and phosphoric salts of
potassium, calcium, iron, magnesium, sodium, copper are common traits of OMW.
In our previous studies, OMW was pretreated by means of chemical oxidation based
on Fenton's reagent, coagulation–flocculation and filtration through olive stones. In this
research work, ion exchange (IE) process is presented as an efficient alternative for
purification of pretreated OMW. Selective resins can reduce the residual concentration
of sodium, iron, chloride and phenol, which are major pollutants in this pretreated
wastewater. A benchscale study was undertaken to assess the performance of a
combination of two ion exchange columns, which worked in serial connection for the
purification of pretreated OMW. The target of this study was to achieve the parametric
requirements for drinking water production, which are established by the Drinking
Water Directive (DWD). In this sense, Council Directive 98/83/EC sets the maximum
concentration in drinking water at 200 mg L-1 for sodium, 200 µg L-1 for iron and 250 mg
L-1 for chloride. Phenol concentration is not established by any directive, but it is
important to avoid it as much as possible, since phenol is a toxic compound.
Temperature is one of the most important parameters affecting the adsorption of the
mentioned pollutants. Simultaneous removal of sodium, iron, chloride and phenol ions
from synthetic water simulating pretreated OMW using a Dowex Marathon C cation
exchange resin and an Amberlite IRA-67 anion exchange resin was examined by
changing operating temperature on two different IE operating modes: batch and
continuous process. The disposition of both resins in the mentioned system was
previously investigated. The results confirmed that using the cation exchange resin
followed by the anion exchange one gave the best results. It was found that
concentrations of all the mentioned pollutants were lower than the maximum
acceptable levels established by the legislation under optimal operating temperature.
Also the IE resins investigated in this study showed reversible uptake of all the studied
ions. Thus, both IE resins have good application potential for the removal these
polllutants from pretreated OMW.