Treatment of lignin enriched paper industry wastewater by electrocoagulation: Modelling approach and economic evaluation

Abstract

Present work covers the treatment of lignin enriched paper industry wastewater (LEPIW) using electrocoagulation (EC) process with stainless steel (SS) electrodes. In this study, EC operation is optimized in term of % chemical oxygen demand (COD) removal and treatment cost (USD/kg COD removed). Single parameter study has been performed to study the effect of process parameters on % COD removal and treatment cost. Central composite design (CCD) of design of expert (DOE) has been used to corelate the input (time, initial COD, solution pH and current) and output parameters (% COD removal and treatment cost). Single parameter study states that maximum % COD removal of 84.4 & 77% is achieved in 40 & 60 min for initial COD:500 &1000 mg/L while 74, 66.7 & 58% can be achieved in 100 min for initial COD of 2000, 3000 & 4000 mg/L, respectively under optimum condition (solution pH:7, current: 1 A). Cost analysis summarizes that treatment cost decreases with increase in initial organic load (2.036, 2.075, 1.554, 1.247 & 1.127 USD/kg COD removed for initial COD of 500, 1000, 2000, 3000 & 4000 mg/L, respectively) at optimum condition. The caloric study states 2.31and 3.25 J/mg can be generated from the sludge and scum produced during EC process. DOE software suggests − 6.66–6.79% & − 16.73–7.95% error between experimental and designed value for % COD removal and treatment cost.