Electrochemical Degradation of Pulp and Paper Mill Wastewater. Part 1. COD and Color Removal

Abstract

The electrochemical degradation of agri-based paper mill wastewater (black liquor) was investigated in a 2 dm3 electrolytic batch reactor using iron plate electrodes. Of the four-, six-, and eight-plate configurations, a current density of 55.56 A/m2 at neutral pH with a six-plate arrangement was found to be optimal, achieving a maximum chemical oxygen demand (COD) and color removal of 80% and 90% (175 platinum−cobalt units (PCU)), respectively. The chemical dissolution of iron was strongly influenced by pH0. Electrochemical treatment at higher pH0 (pH0 ≥ 9) increases the dissolution of iron electrodes by an order of magnitude. At the optimal current density, the iron electrode consumed is 31.27 g/m2·h, achieving maximum COD removal. An increase in salinity reduces the treatment time significantly, and the sludge settling characteristics also improve. The addition of polyacrylamide (10 mg/dm3) to the electrochemical reactor enhances the COD removal rate with a very short treatment time with excellent slud...