Abstract
Simulated wastewater containing 20ppm of Zn++, 20ppm of Ni++ was treated using an electrochemical technique. This synthetic wastewater was used to simulate the wastewater from metal finishing industries. A rectangular bath integrated with an electrochemical cell consisting of flat plate electrodes (the stainless steel anode and aluminum cathode) was used in the treatment. Potassium sulfate was used as a supporting electrolyte to enhance the removal of Zn++ and Ni++. The effects of volumetric liquid flux, pH and electrode surface area on Zn++ and Ni++ removal were investigated. All experiments were performed at 25ºC and at an applied voltage of 4V. When volumetric flux was raised from 0.0092 to 0.0277m³.m-².s-¹, an increasing trend of the Zn++ and Ni++ removal was observed. The maximum metal removal was observed at a volumeteric liquid flux of 0.0231m³.m-².s-¹. Zn++ and Ni++ were removed by 80% and 34%, respectively, after 48 hours of electrochemical treatment. Moreover, an increase in the removal of Zn++ and Ni++ was observed when the pH was varied from 3.5 to 6.5. The maximum removal of Zn++ and Ni++, 97% and 62%, respectively, occurred at a volumetric liquid flux of 0.0231m³.m-².s-¹ and a pH of 6.5. The experimental values showed a similar increasing trend in the removal of Zn++ and Ni++, when the electrode surface area was increased from 0.024m² to 0.048m²; the removal of Zn++ and Ni++ improved by 14% and 12%, respectively. However, there was no major change in the removal of Zn++ and Ni++ between flat plate and corrugated plate electrodes.
Highlights
To examine the effect of the volumetric liquid flux on the removal of zinc and nickel ions, electrochemical treatment was done at different volumetric liquid fluxes, ranging from 0,0092-0.0277m\m‘^.s'' in the laminar regime, corresponding to Reynolds number 717 to 2159
It can be noted that the percent removal of zinc increased with a corresponding increase in the volumetric liquid flux
The percent removal of zinc increased from 70% at 0.0092m^.m" ^.s‘* to 80% at 0.023 Im^.m'^.s'V The removal of zinc ions started decreasing at a volumetric liquid flux of 0.0277m^.m'^.s'^
Summary
1 IntroductionThe water management is one o f the most critical issues in the coming decade. Water resources may even suffer drastic variations on a global level because o f the foreseen population growth and climate changes. This fact, in combination with the water pollution caused by mankind activity, makes water re-use of utmost importance. One should keep in mind from global prospect that recycling of water is not environmentally benign if highenergy input technologies are used for this purpose [2], the development o f efficient wastewater treatment technologies with low energetic and operational costs is essential for all types o f wastewater. Industrial wastewater contributes 42.4% o f the total volume of wastewater in the world [3]
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