Tertiary treatment of pulp and paper industrial wastewater by electro-Fenton process.

The feasibility of decolourisation/degradation of secondary treated pulp and paper industrial wastewater was investigated by Electro-Fenton process. The wastewater was dark brown in colour, toxic odorous, having high COD (34,800 mg/L), BOD3 (4900 mg/L) and non-biodegradable (0.14--BOD3/COD ratio). The study was carried out to evaluate the effects of the operating variables, viz. pH, dosage of Fe2+, concentration of hydrogen peroxide, current efficiency and contact time. The kinetic results show pseudo-first order degradation, with a rate constant of reaction between CODt/COD0. The maximum colour removal up to 95% and COD removal upto 90% were obtained at pH 3, Fe2+ dosage 125 mg/L, concentration of H2O2, 1500 mg/L, applied current 2.2 A for 120 minutes of contact time. This feasibility study has proved that Electro-Fenton process could be an appropriate tertiary treatment for secondary treated pulp and paper industrial wastewater.