Esparto paper industry wastewater treatment by adsorption onto powdered activated carbon

Abstract

ABSTRACT The discharge of Esparto paper industrial wastewater (EPIW) of SNCPA Company of Kasserine – Tunisia in nature without any treatment can cause harmful effects to the environment. To reduce this danger, several treatment processes have been implemented, in particular, the adsorption technique. The present original study consists of using powdered activated carbon (PAC) to treat EPIW. The tests were carried out on different chemical oxygen demand (COD) concentration of EPIW ranging from 2 to 20 g/L. The influence of initial COD concentration, adsorbent dose, pH and contact time were investigated at temperature of 25 ± 2°C. The equilibrium results were modelled and assessed via Freundlich, Langmuir, Temkin and Dubunin–Radushkevich isotherms models. The error analysis was evaluated by three error functions: the average relative error deviation, the Marquardt’s percent standard error deviation and the Sum of the squares of the errors. The results showed that COD removal efficiency, maximum adsorption capacity and colour removal rate were 94%, 190 mg/g and 90%, respectively, for pH = 6, an adsorbent dose of 75 g/L, initial COD concentration of 9.3 g/L and contact time of 60 min. Besides, the main characteristics values of treated EPIW (BOD, TCOD, pH and Salinity) at natural conditions were 200 ± 30 mg O2/L, 1300 ± 50 mg O2/L, 7.2 ± 0.1 and 1.7 g/L ± 0.1, respectively, which were below the ISO-14,000 standards conditions for release in public sewerage system. Furthermore, both the higher value of correlation coefficients (R2) and the lower value of SSE have shown that Freundlich model provided the best fits to adsorption experimental results.