Treatment of wastewater from pulp and paper mill industry by electrochemical methods in membrane reactor

Abstract

The treatment of wastewater from a pulp and paper mill plant using electrochemical methods was performed at a laboratory bench-scale at ambient temperature (∼30 °C). The effects of wastewater dilution (10- to 100-fold), circulating water flow rate (0–3.95 l/min), current density (1.90–3.80 mA/cm2) and sodium chloride concentration (0–3.75 g/l) were ascertained. The results demonstrated that this methods can facilitate the disappearance of the oxidative coupling unit of lignin as well as other organic and inorganic compounds, measured in terms of the removal of color, total biological- and total chemical oxygen demand (BOD and COD), and the total suspended and dissolved solids (TSS and TSD). In addition, the electrochemical method was more effective at reducing the pollutant levels, produced a smaller quantity of low-density sludge and had a low operating cost per unit quantity of COD. After optimization, the electrochemical method operating in a batch mode enhanced the removal of color, BOD and COD at around 98%, 98% and 97%, respectively, whilst in a continuous mode at the steady state condition (8 h after the start-up time) the color, BOD and COD levels were reduced by around 91%, 83% and 86%, respectively.