Effect of operational parameters on treatment of textile wastewater by electrocoagulation process using different electrode materials
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Date
2018-07-01
Authors
Marwa Ali Elaje
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Abstract
Electrocoagulation process (EC) has been used to overcome the problems
related to the use of conventional physico-chemical process in treatment of textile
wastewater. Real textile wastewaters containing reactive dyes are often characterized
by their alkalinity. Different electrode materials such as zinc and stainless steel could
be used to tackle the low performance of aluminum electrode in alkaline medium for
treatment of a real textile wastewater. The performance of electrocoagulation process
for treatment of a synthetic textile wastewater (prepared using reactive blue 261 dye)
and a real textile wastewater was investigated. Three types of electrode material
namely aluminum, zinc and stainless steel were used in this study. The operating
parameters involved in this study were current density (2-8 mA/cm2), initial dye
concentration (20-100 mg/L) and initial pH (5-9). The preliminary study was
conducted using synthetic textile wastewater to determine the best operating
conditions that would lead to high dye removal for each electrode material. The best
conditions were current density (4 mA/cm2 for all electrodes), initial dye concentration
(50 mg/L for aluminum electrode and 100 mg/L for zinc and stainless steel electrode)
and initial pH (7 for aluminum electrode and 9 for zinc and stainless steel electrode).
A thorough investigation in terms of dye removal, COD, turbidity, energy
consumption and electrode weight loss was conducted under the best conditions
(current density and initial dye concentration) while the initial pH value was kept at 9
to represent the real textile wastewater condition as used in this study. Dye removal,
power consumption and electrode weight loss were found at 99.8%, 0.66 kWh/m3 and
0.039% for zinc electrode, 99.1%, 0.70 kWh/m3 and 0.066% for stainless steel
electrode and 75.8%, 0.50 kWh/m3 and 0.41% for aluminum electrode, respectively.
The treated real textile wastewater under the best operating conditions (current density
and initial dye concentration) and at original pH of textile wastewater demonstrated
that zinc electrode showed the highest dye removal (83.7%), lowest electrode weight
loss (0.043%) and reasonable energy consumption (0.69 kWh/m3). The estimated
operating cost of the EC process was lower for zinc electrode (MYR 3.9 per 1 m3 of
treated textile wastewater for 10 minutes) compared with aluminum and stainless steel
electrodes. Thus, zinc electrode could be an effective electrode material for treatment
of textile wastewater containing reactive dye.