Treatment of wastewater using a combined biological and electrochemical technique

Abstract

Simulated wastewater containing propylene glycol methyl ether, Ni 2+ and Zn 2+ was treated using an aerated packed column. An electrochemical cell was also installed beneath the packing support in the bottom section of the column. The flowrate of water through the column was maintained at 8.94 kg m −2 s −1 . For 72 h of treatment using aeration alone, the BOD 5 was reduced by 43%, 56%, and 54% for air flowrates of 0.00094, 0.00141, and 0.00188 kg m −2 s −1 respectively. On the other hand, when the electrochemical cell was activated without aeration, the BOD 5 was reduced by 15%, 17%, and 23% at the applied voltages of 8, 16, and 25 V respectively. When both aeration of the wastewater and a voltage of 25 V were used, the percentage removal of BOD 5 , on the average, was about 65% for all air flowrates used.

Combined electrochemical and biological treatment of industrial wastewater using porous electrodes

“…Zn 2+ removal was more favourable at this pH. This was also observed by others such as Simonsson 22 and Doan et al 8 The standard reduction potential of Zn 2+ is greater than that of Ni 2+ , implying that Ni 2+ should be reduced more readily than Zn 2+ . However, the results obtained showed that Zn 2+ was actually removed to a greater extent than Ni 2+ .…”

“…A similar observation was also reported by several researchers who worked in treating dilute metallic wastewater. 8,17,18 In the electrodeposition of metal ions using insoluble anodes, the bulk pH usually decreases owing to the electrolysis of water releasing H + into the solution. 19 Under neutral and acidic conditions the electrolysis of water at the anode can be described as 20…”

Recovery of Zn(II) and Ni(II) Binary from Wastewater Using Integrated Biosorption and Electrodeposition

“…Doan et al studied the effect of the electrolyte pH on Zn(II) and Ni(II) binary electrodeposition. The data indicated that the best metal deposition occurred at an electrolyte pH of about 6.0 . Likewise, Orhan et al studied nickel deposition from an aqueous solution.…”

Recovery of Zn2+ and Ni2+ binary from wastewater using integrated biosorption and electro-deposition

“…A feed tank was filled with an electrolyte solution (the concentrated Zn-Ni metals solution from biosorbent regeneration), and 1000 ppm of potassium chloride was added, as a supporting electrolyte, to enhance the electric current flow. The electrolyte pH was maintained at 5.5 -6.0 over the experiment duration (Simonsson, 1984;Orhan et al, 2002;Doan et al, 2003).…”

“…The electrolyte pH is one of the most important factors that have a crucial effect on the metal removal. Doan et al (2003) studied the effect of the electrolyte pH on Zn 2+ and Ni 2+ binary electro-deposition. The data indicated that the best metal deposition occurred at an electrolyte pH of about 6.0.…”