Evaluation of industrial sludge produced from textile and leather industrial wastewater in energy and environmental applications

In this study, catalytic (y-zeolite and activated alumina) and non-catalytic pyrolysis properties of sludge obtained from the biological treatment of leather and textile industrial wastewater plants were investigated by different methods. Iso-conversional model-free methods, such as Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and Friedman were utilized to evaluate the kinetic and thermodynamic parameters. The calculated average E_a (activation energy) values of catalytic and non-catalytic pyrolysis with y-zeolite and activated alumina (Al2O3) were determined to be in the range of 170.63-182.77, 117.78-123.1 and 129.32-135.92 kJ/mol, respectively. GC/MS analyses showed that the oil obtained from the non-catalytic procedure was rich in fatty acids, steroidal compounds, and N-compounds. Activated alumina was very effective in removing nitrogen containing compounds from the oil. On the contrary, y-zeolite promoted de-oxygenation and de-acidification reactions and, as a result, the oil became rich in alkanes and alkenes which improved its quality as a fuel. As a result, y-zeolite can be used as an effective catalyst to improve the decomposition rate of sludge, and to upgrade the pyrolytic oil. of the experimental studies, activated carbon was produced at different carbonization temperatures and saturation rate to evaluate the solid product obtained by the pyrolysis of the sludge. For this purpose, a two-factor experimental design method, 4-level carbonization temperature and 2-level saturation ratio, was carried out. In the second stage, to evaluate the solid residue of sludge an activated carbon were produced at different carbonization temperature and different impregnation rate, for this reason a full factorial experiment was designed with two factors which are carbonization temperature with 4 levels and impregnation ratio with 2 levels. As a result, Carbonization temperature (℃) was the most effected factors on surface area by 69.07 % contribution. Therefore, surface area increased with the increase of the temperature until achieved the maximum at 550 ˚C then decreased with the increasing of the temperature.