Effect of controlled and uncontrolled pH on tannery wastewater treatment by the electrocoagulation process

In this study, the effects of the pH of tannery wastewater obtained from a local leather processing factory on the removal of COD and turbidity, and cost of theelectrocoagulation process was investigated. Studies were carried out under two different operatingconditions. The highest COD removal efficiency was obtained as 83.5% when the initial pH was set to 3, while the energy consumption at this pH was found to be 3.88 kwh m(-3). In studies where pH was kept constant, the highest removal efficiency obtained was 83.33% at pH = 5. In this case, the energy consumption was determined as 2.44 kWh m(-3). The total cost of the system was calculated as 1.0899 $ m(-3) under controlled pH conditions and 0.8761 $ m(-3)with uncontrolled pH. Studies show that the COD removal kinetics are more suited to 2nd degree kinetics. The highest removal rate for uncontrolled pH was k(2) = 0.0791 L g(-1) min(-1) at pH = 3. The highest rate for controlled pH was k(2) = 0.0397 L g(-1) min(-1) at pH = 5.