Pilot Treatment of OCC-based Paper Mill Wastewater Using Pulsed Electrocoagulation

There is an increasing trend towards the closure of white water recirculation loops in papermaking, often leading to need for system modification A pilot-scale study was conducted using pulsed electrocoagulation technology to treat the wastewater of an old corrugated containerboard (OCC)-based paper mill, to evaluate its treatment performance The operating variables were a current density of 0 to 240 A/m(2), a hydraulic retention time of 8 to 16 mm and a coagulant (anionic polyacrylamide) dosage of 0 to 30 mg/L The water quality indicators investigated were electrical conductivity, suspended solids (SS) and chemical oxygen demand (COD) The results obtained during the pilot-scale studies were favourable Under the operating conditions without coagulant addition, the highest removals for conductivity, SS and COD were 47 7%, 99 3% and 75%, respectively The use of coagulant remarkably enhanced the removal of both conductivity and COD Using a coagulant dosage of 30 mg/L, the highest removal rates achieved for the three water quality indicators were 54 5%, 99 6% and 92 7%, respectively These water quality levels are adequate to allow for the reuse of at least a part of the treated wastewater as makeup process water in papermaking