Batch Electrocoagulation Process for Removal of Chromium from Tannery Wastewater

Abstract

This study was aimed to investigate the chromium removal from the tannery wastewater through electrocoagulation. The zinc and copper plates were used as electrodes for the electrocoagulation process. The effectiveness of the electrocoagulation for chromium removal efficiency was examined investigating various parameters: applied voltage, time, and current density. In batch experiment, 500 mL chromium-containing wastewater was used for electrocoagulation. Chromium content in the raw wastewater and after treatment at optimized conditions was 340.1 and 6.9 mg/L, respectively. The efficiency of chromium removal and reduction of biochemical oxygen demand (BOD) was at 98.0 and 64.6%, accordingly. Although total dissolved solids (TDS) was slightly increased. The increment of current density enhances forming zinc hydroxide which causes the damage of electrodes. Electrocoagulation is an effective technique to remove chromium from the wastewater especially from the tannery wastewater.
 Journal of Engineering Science 12(1), 2021, 29-34

Electrocoagulation Process for Chromium Removal in Leather Tanning Effluents

“…Prolonging the electrocoagulation process further amplified the separation of metal ions (Zaied et al, 2020). As depicted in Figures 4-6, an increase in process time correlated with a decrease in the Cr content, attributed to the accelerated oxidation of Cr 3+ and the formation of Cr(OH) 3 , generating small particles that formed settleable flocs (Hasan et al, 2021). The reduction in the Cr content was also influenced by the concentration of Al 3+ cations in the wastewater, where a higher concentration led to increased cation absorption into the solution.…”

“…Specific energy, denoted in kilowatt-hours (kWh), represents the energy required to eliminate 1 kg of total Cr mass. A lower specific energy value indicates greater efficiency in the electrocoagulation process, thereby reducing the overall cost associated with the Cr removal from wastewater (Hasan et al, 2021). When examining the results it was found that the lowest specific energy of 5.67 kWh/kg Cr was achieved under conditions of pH 4, an electric current of 0.5 A, and a duration of 1 hour.…”

Optimization Through Box-Behnken Design for Cr(VI) Degradation from Real Tannery Wastewater Using Graphite Electrode by Electrocoagulation

“…Statistical estimates indicate, ~90% of tanneries employ the usage of chrome sulfate to carry out tanning operations where effluents of tanning contain ~4000 mg/L chromium, which is substantially higher than the WHO maximum acceptable level. The unregulated and improper discharge of effluent from tanneries degrades the water quality [5]. Cr (VI) occurs as a CrO-24 in water.…”

“…Chromium is non-recyclable and if present in trace quantities in human body, it may accumulate leading to health issues such as hemorrhage, itching, chest discomfort, and skin irritation. Although such effects can be reduced by treatment of tannery effluent prior to their release into the environment [5]. The Government of India has set an upper limit for effluent discharge from leather companies and is providing technical assistance for the re-installation, modification and upgradation of wastewater treatment (WWT) plant facilities to treat wastewater before it is dumped into the local water bodies.…”