Abstract:
Skins/ hides are transformed into leather through many complex stages, consuming high quantities of water and using large amounts of chemicals. The leather tanning industry has been identified as one of the main causes of environmental pollution in Ethiopia. In general, tannery wastewaters have a dark brown and have a high content of organic substances that vary according to the chemicals used. Soaking wastewater have more of high organic and NaCl.
Tanneries in Ethiopia generate large amount of soak wastewater and discharge to the surrounding environment with partial treatment sometimes without any treatment and cause environmental pollution and public health problem.
Soak liquor, a primary effluent from the tannery industry has contain high organic load (flesh, skin, blood, humic substances and other suspended particles) and sodium chloride (salt), making a challenge for the conventional treatment technologies.
An electro oxidation wastewater treatment method was investigated to treat tannery waste liquor for the effective discharge of the final effluent. A series of batch electro oxidation experiments for a wide range of contact time (30 – 120 minutes), different salt concentration (13.5g/L – 15 g/L) and at a current density of 0.012A/cm2 were performed for the effective removal of the liquor waste. Optimal removal efficiency of 85.86%, and 84.31% and 12.51% of COD, BOD and TDS respectively were recorded over the factors level of a contact time of 120 minutes, and at pH of 8 and 9. Highest reduction in COD and BOD were observed as 84.4 % and 84.06 % at salt concentration of 15 g/L.
The present study claims that the process of EO gives better performance on reduction of COD and BOD while comparing previous studies.