Optimization and Cost Analysis of Electrocoagulation for Phenolic Syntan Removal from Synthetic Tannery Wastewater

Abstract

Syntans are phenol-based synthetically produced tanning agents used in tanneries for improving the filling, grain properties and dyeing property of the hide. A significant portion of syntans emanating in the tannery effluents along with other heterocyclic aromatic compounds have high pollution load and imposes severe environmental impact. Hence, the present study adopted an Electrocoagulation (EC) method with perforated aluminum electrodes for the removal of phenolic syntan (PS) from PS bearing synthetic tannery wastewater. The one-variable-at-a-time (OVAT) experimental analysis was performed to optimize the PS removal efficiency. The OVAT experiments were studied to understand the impact of operating parameters, i.e. initial pH (3 - 7), current density (5.8 - 23.6 mA/cm²), and initial phenolic syntan (PS) concentration (0.25 - 1.5 g/L). The mixing speed was maintained at 200 rpm in each experiment. The results demonstrated that the EC process could efficiently remove PS (83.43%) from synthetic wastewater at the following operating condition: initial pH= 4, current density= 17.64 mA/cm² and initial PS concentration= 0.25 g/L, and electrolysis time = 90 minutes. The cost analysis showed the economic feasibility of EC techniques with a total cost of $3.46/m³ and demonstrated the need for a balance between the EC unit effectiveness and operating costs for economically viable wastewater treatment in the tannery sector. The study provided valuable information for improved sustainable and economical effluents treatment techniques in tanneries.