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

There are increasing trends toward closure of white water recirculation loops in papermaking often leading to needs of system modification. A pilot-scale study was conducted using pulsed electrocoagulation technology to treat the wastewater of an OCC (old corrugated container board)-based paper mill, with the purpose of evaluating its treatment performance. The operating variables were a current density of 0~240 A/m2, a hydraulic retention time (HRT) of 8~16 min, and a coagulant (anionic polyacrylamide) dosage of 0~30 mg/L. Water quality indicators investigated were electrical conductivity, suspended solids (SS), and chemical oxygen demand (COD). The results obtained during pilot-scale studies were encouraging. 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 removals achieved for the three water quality indicators were 54.5%, 99.6% and 92.7%, respectively. Such water qualities are adequate to allow reuse of at least a part of the treated wastewater as process water makeup in papermaking.