International Journal of Environmental Science and Technology
Treatment of oil renery wastewater
by electrocoagulation–occulation (Case Study: Shazand Oil Renery
· A. R. Karbassi
· M. Reyhani
Received: 7 March 2018 / Revised: 14 May 2018 / Accepted: 22 May 2018
© Islamic Azad University (IAU) 2018
In the present study, electrocoagulation–ﬂocculation method was used to treat the wastewater from Shazand Oil Reﬁnery
in Arak, Iran. The wastewater contained 170,000 mg/L COD and 5.3 mg/L lead (Pb). In each step of the experiment, 2 L of
the reﬁnery wastewater was poured into a pilot made up of Plexiglas, and bipolar electrode arrangement was used. Optimum
values of time, pH, and voltage parameters were determined for the aluminum electrodes. Results showed that time duration
of 90 m, pH of 6, and voltage of 30 V was suitable for the removal of lead and COD. It should be noted that 48% of COD was
removed and lead concentration decreased from 5.3 mg/L to lower than 0.05 mg/L. In addition, the COD removal eﬃciencies
were 56 and 64% for eight and ten aluminum electrodes, respectively. The eﬀect of iron electrodes on the removal of COD
and lead was investigated under the same optimum conditions. Comparison between iron and aluminum electrodes indicated
that iron electrodes demonstrate a better eﬃciency by removing 66.94% of COD from wastewater. It was also found that pH
played a signiﬁcant role in pollutants removal due to the formation of aluminum hydroxide gelatinous polymer.
Keywords Lead · COD · Environment · Pollution · Treatment plant · Oil
Increasing growth of industries worldwide has lead to exces-
sive use of water resources in diﬀerent processes. It is vital
to reduce the exploitation of these resources by adopting
new and eﬃcient techniques in industrial sector. In this
direction, wastewater treatments have to be studied so as to
facilitate the reuse of treated wastewater in diﬀerent indus-
trial processes (Dermentzis et al. 2011). Due to the extensive
application of heavy metals in various industries such as
oil reﬁning industry, the produced wastewater usually con-
tains high concentrations of heavy metals (Ibrahima and
Jaddob 2013), which directly aﬀect the treatment process.
Moreover, these metals disable microorganisms and inhibit
their biological activity in common biological treatments
due to their toxicity and ﬁnally result in improper treatment.
Therefore, the output wastewater from common treatment
procedures does not comply with the environmental stand-
ards and cause irreversible harms to the environment due
to its toxicity, non-degradability, and bioaccumulation of
heavy metals (Fu and Wang 2011; Bestawy et al. 2013).
Various techniques such as chemical precipitation, absorp-
tion, ion exchange, and reverse osmosis are used for treat-
ment of industrial wastewaters (Ahmad et al. 2005; Lu et al.
2015). These techniques are usually expensive (Khandegar
and Saroha 2013). Among these techniques, chemical pre-
cipitation is the most common one, but it has disadvantages
such as excessive amount of sludge and secondary pollution
produced by chemical coagulants (Lu et al. 2015).
Electrocoagulation–ﬂocculation is one of the new and
eﬃcient methods for treatment of industrial wastewater.
Some of the advantages of this method are: high-speed
treatment, eco-friendliness (Bouamra et al. 2012; Demir-
bas and Kobya 2017; Gong et al. 2017; Vandana et al.
2017; Kausley et al. 2017; Liu et al. 2016), lack of chemi-
cal compounds, considerable decrease in output sludge
(Tak et al. 2015), and transparency of treated wastewater
Editorial responsibility: M. Abbaspour.
* T. Shahriari
Faculty of Environment, University of Tehran, Tehran, Iran
Present Address: No. 25, Azin Ave., Qods Street., Enghelab
Street, Tehran, Iran