THE REMOVAL OF CHROMIUM FROM SYNTHETIC TANNERY WASTEWATER USING ACTIVATED CARBON

Wastewater released in to environment from industrial sector without proper treatment cause impacts on environment and humans. One of the industry sectors that can produce a large quantity of wastewater is leather tanning industry. The wastewater from this industry has heavy metals and must be treated before released to the environment. Chromium is one of the popular chemical widely used in leather tanning industry. So, the wastewater from this industry has high amount of chromium, which is very toxic and carcinogenic. In other ways, treating wastewaters cost the industries large amount of money. Therefore, the aim of this research is to remove chromium from tannery wastewater by adsorption using activated carbon prepared from locally available and low-cost plants known as parthenium under factorial study design of 24 (16 runs, the combinations of four independent variables). Factorial study design is known for its simplicity, cost-effectiveness, less time consuming, and to interaction among variables. In this factorial study, four independent variables such as, pH, time, initial concentration, and adsorbent dosage, and one dependent variable, removal efficiency were considered. For optimization purpose, the synthetic tannery wastewater was prepared in the laboratory. The characterization of activated carbon developed from parthenium stem such as; Proximate analysis, scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and surface area determination were performed. The results of adsorption tests done on synthetic wastewater showed that the prepared activated carbon was able to remove 90.54 % of chromium from wastewater at pH 2, Contact time of 90 minutes, adsorbent dosage of 10 g/110ml solution, and initial chromium concentration of 100mg/L. After optimization the test was repeated on the actual tannery wastewater and the removal efficiency of the adsorbent was 89% which proved activated carbon prepared from parthenium stem can be used to treat the wastewater of the leather tanning industrial sector. Finally, the treatment system was tested by two well know isothermal models in water and wastewater treatment system, Langmuir Freundlich isotherms. And the Freundlich isotherm was best fitted with the experimental data