Electrochemical Treatment Of Textile Dye Wastewater By Aluminium And Stainless-Steel Electrodes

ABSTRACT

Pollution of water resources due to the increasing growth in industrialization

continues to pose a great challenge to the rapidly growing population. Textile

industries are among the principal polluters of surface water. The development of

these textile industries has resulted in severe water pollution due to discharge of dye

wastewaters to natural water courses. This laboratory scale study was aimed at

establishing an eco-friendly wastewater treatment method dubbed electrocoagulation

(EC) method. The main objective of the study was to establish an

electrochemical and efficient method that would effectively remove COD and colour

from azo dye wastewater using aluminium (Al) and stainless steel (SS) electrodes.

Increasing current density and contact time significantly increased the removal of

colour and COD. Increase in current density increased both COD and colour

removal. When current density was increased from 15 to 47 A/m2 the colour

removal increased from71 to 99 % for the case of disperse blue with SS electrode.

Increase in contact time 5- 20min. caused increase in colour and COD removal from

below 50 to 98 and 78 % respectively for disperse blue with SS. When interelectrode

distance (IED) and dye concentration was increased the colour and COD

removal declined significantly. As the IED increased from 1-3cm the percentage

removal of colour decreased from 99 to 45 % for the case of disperse blue with SS.

Addition of sodium chloride enhanced the electrocoagulation process. Addition of

NaCl from 0 - 0.4g enhanced colour removal from 15 to 80% for disperses black

with SS. Under optimum operating conditions (current density 47.2 A/m2, Interelectrode

distance 1cm, SE 0.2 g/L, 0.1 g/L dye concentration and 25 minutes

contact time) the performance of stainless steel on removal of colour recorded the

highest removal at 97% compared to that of aluminium of 90%.the physio-chemical

parameters where reduced to NEMA disposable levels making it possible for treated

water fit for re-use. COD reduced by 81%, conductivity by 89% and turbidity by

88%. Operating cost was evaluated by adding cost of electrode per Kg at the market

price and the cost of electricity per (kWh/m3) for SS= 50.56 KES/m3 and Al =50.55

KES/m3. This confirms the viability and a cost-effectiveness of the process.