Removal of phenol from steel wastewater by combined
electrocoagulation with photo-Fenton
Mohammad Malakootian and Mohammad Reza Heidari
ABSTRACT
Phenol and its derivatives are available in various industries such as refineries, coking plants, steel
mills, drugs, pesticides, paints, plastics, explosives and herbicides industries. This substance is
carcinogenic and highly toxic to humans. The purpose of the study was to investigate the removal of
phenol from wastewater of the steel industry using the electrocoagulation–photo-Fenton (EC-PF)
process. Phenol and chemical oxygen demand (COD) removal efficiency were investigated using the
parameters pH, Fe
2þ
/H
2
O
2
, reaction time and current density. The highest removal efficiency rates of
phenol and COD were 100 and 98%, respectively, for real wastewater under optimal conditions of
pH ¼ 4, current density ¼ 1.5 mA/cm
2
, Fe
2þ
/H
2
O
2
¼ 1.5 and reaction time of 25 min. Combination of
the two effective methods for the removal of phenol and COD, photocatalytic electrocoagulation
photo-Fenton process is a suitable alternative for the removal of organic pollutants in industry
wastewater because of the low consumption of chemicals, absence of sludge and other side
products, and its high efficiency.
Mohammad Malakootian
Environmental Health Engineering Research
Center,
Kerman University of Medical Sciences,
Kerman,
Iran
and
Department of Environmental Health, School of
Public Health,
Kerman University of Medical Sciences,
Kerman,
Iran
Mohammad Reza Heidari (corresponding author)
Environmental Health Engineering, Department of
Environmental Health, School of Public Health,
Bam University of Medical Sciences,
Bam,
Iran
E-mail: moheidari86@gmail.com
Key words | electrocoagulation, phenol, photo-Fenton, steel plant
INTRODUCTION
One widespread form of organic chemical pollutant is
phenol and its compounds, which are found in industrial
wastewater (Malakootian et al. ). These compounds
are very dangerous because of their high toxicity and harm-
ful impact on the environment. High concentrations of
phenol and its compounds are commonly found in effluent
from oil refineries and industries such as petrochemicals,
ceramics, coke and steel, coal conversion processes, resin
manufacturing, drugs, pesticides, plastics, explosives and
herbicides industries (Alizadeh et al. ). The presence
of phenol in drinking and irrigation water is a serious
threat to the health of humans, animals, plants and microor-
ganisms (Fajardo et al. ). Phenol is highly carcinogenic
to humans and causes significant health concerns even at
low concentrations (Farhadi et al. ). Its toxic effects
include permeating cell membranes and cytoplasmic
coagulation. The standard amount of phenol in drinking
water is 0.5 mg, while the limit for effluent from industrial
waste output is 1 mg/L. There are many methods for
phenol removal, which include adsorption (Liu et al. ),
chemical oxidation (Hernández-Francisco et al. ),
biological methods (Priyadharshini & Bakthavatsalam
), distillation, extraction, ion exchange, membrane pro-
cess, reverse osmosis and electrochemical techniques
(Víctor-Ortega et al. ). Physical methods for removal
of phenol are expensive and inefficient.
Presently, chemical methods are not used due to their
disadvantages such as high maintenance costs, sludge
issues and disposal problems. Electrooxidation methods
are a good alternative for the treatment of organic pollutants
(Farhadi et al. ). The conventional biological processes
cannot be used for the complete treatment of industrial
wastewater due to high toxicity and carcinogenicity, high
chemical and physical resistance of the pollutants, and
also, bacteria or fungi are sensitive to changes in the
environmental parameters.
Electrocoagulation (EC) has been used in the treatment
of urban wastewater (Yavuz & Ögutveren ), effluents of
oil (Gobbi et al. ), dyes (Khemila et al. ), antibiotics
(Baran et al. ), sulfate (Mamelkina et al. ) and cad-
mium (Malakootian et al. ). The EC process involves
the formation of metallic hydroxides in the effluent by dis-
solving the electrodes (anodes), usually formed by iron or
aluminum. A coagulant with no impurities or extra metal
1260 © IWA Publishing 2018 Water Science & Technology | 78.6 | 2018
doi: 10.2166/wst.2018.376
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