High-rate humic acid removal from cellulose and paper industry wastewater by combining electrocoagulation process with adsorption onto granular activated carbon

Abstract

The cellulose and paper industry produces large volumes of wastewater which are difficult to treat due to large concentrations of Humic acid (HA). In subsurface water, HA can react with active chlorine to produce carcinogenic compounds causing different ecological problem and danger to human health. The main objective of the present study is to investigate the influence of electrocoagulation (EC) process parameters using aluminum (Al) electrodes to remove HA from synthetic solution, and then studies the efficiency of the coupling of electrocoagulation and the adsorption on active carbon (GAC). It has been observed from the experimental results that the best removal of HA by EC was obtained with the following optimum conditions: initial pH of 4, current density of 1.388 mA cm−2, Na2SO4 concentration of 150 mg L-1 and EC time of 10 min. These operating conditions allow a removal percentage up to 93% with 0.033 KWh m-3 of power consumption by EC and the same removal ratio was achieved for a treatment time of only 2 min by combining adsorption onto GAC with EC with a decrease of power consumption (0.007 kW h m-3). Accordingly, our results displayed prominently that combination of electrocoagulation with adsorption on GAC notably reduces the treatment duration without inducing a strong increase of cost. The current study extends our investigation of these promising processes to wastewater applications, employing samples of cellulose and paper industrial wastewater. The results suggest that combining adsorption onto GAC with EC could greatly improve the economics of treatment of wastewaters generated in cellulose and paper industry by extending efficiency through reduced treatment time and cost. HA was completely removed from Tunisian industrial wastewater with a very low energy consumption (0.0183 KW h m-3) and treatment cost of 0.233 TND.