Electrochemical treatment of alkali decrement wastewater containing terephthalic acid using iron electrodes

• Electrochemical treatment of alkali decrement wastewater containing terephthalic acid.
• Optimization of parameters like pH, current density, time and electrode distance.
• Studies on slurry and residues.
• Study of settling characteristics of treated effluent.
• Thermal decomposition of residues investigated.

In this study, treatment of simulated alkali decrement wastewater containing terephthalic acid (TPA) has been investigated by electrochemical treatment using stainless steel as electrode material. Five operational parameters, namely current density: 31.25–156.25 A/m2; electrode gap: 1–2 cm; NaCl concentration: 0–2 g/l; pH: 7–12 and TPA concentration: 400–1000 mg/l were investigated for their effect removal efficiency. For a solution having 400 mg/l TPA and 560 mg/l chemical oxygen demand (COD), 72% COD removal and ≈77% TPA removal efficiency was obtained at optimal conditions of current density ≈ 118 A/m2, electrode gap = 1 cm and pH ≈ 7. Presence of ethylene glycol in the wastewater was found to decrease the treatment efficiency. Settling characteristics of the slurry obtained at optimum condition have been studied. Thermal decomposition of residues has also been investigated.