Adaptability of Teff husk activated carbon for removal of hexavalent chromium from tannery wastewater at optimized process condition

Tsegaye Adane,Awrajaw Dessie

doi:10.1007/s13201-020-01269-1

Abstract

Tanneries are the major contributors to chromium pollution of the environment. Exposure to chromium (VI) can cause cancer, brain damage, central nervous dysfunction, blood composition damage; damage of lungs, kidneys, liver, and other vital organs. Although various studies have been done on the removal of Cr (VI) from synthetic wastewater, there is a lack of study in the adaptability of these methods in the treatment of real wastewater and expanding to the industrial application level. Therefore, the present study was aimed to examine the effectiveness of Teff husk activated carbon for the removal of Cr (VI) from tannery wastewater at optimized process conditions. The laboratory-based study was conducted to determine the Cr (VI) removal efficiency of Teff husk activated carbon from tannery wastewater. Data were entered and analyzed using SPSS version 20 statistical software. A paired sample t test was also used to test the presence of a significant difference in the mean concentration of Cr (VI) before and after treatment of the wastewater with Teff husk activated carbon. Then p value < 0.05 was considered as a cutoff point for the presence of a mean significant difference. The removal efficiency was found to be 89.5%. There was a significant difference in the mean concentration of Cr (VI) before and after treatment with Teff husk activated carbon with a = 956.899 and p value < 0.001. This implies the Teff husk activated carbon was an efficient adsorbent for removal of hexavalent chromium from real wastewater. Column adsorption needs to be studied in the future.

Highlights

Human activities that use water produce wastewater
The conventional chrome tanning may lead to 1500–3000 parts per million of chromium in wastewater, whereas the recent chrome tanning method may lead to the release of wastewater containing 500–1000 ppm of chromium (Dargo and Ayalew 2014)
The hexavalent chromium removal efficiency of Teff husk activated carbon (THAC) from synthetic wastewater was determined in the previous study (Adane et al 2020)

Summary

Introduction

Human activities that use water produce wastewater. Industrial wastes are generated from different processes and the amount and toxicity of waste released vary with its specific industrial processes (Belay 2010). Most tanneries in the world (about 90%) use chromium salts to produce leather through the chrome tanning method, because these salts provide better leather flexibility, better water resistance, and a high shrinkage temperature. The conventional chrome tanning may lead to 1500–3000 parts per million (ppm) of chromium in wastewater, whereas the recent chrome tanning method may lead to the release of wastewater containing 500–1000 ppm of chromium (Dargo and Ayalew 2014). This is beyond the WHO tolerance limit for Cr (VI) to be discharged into inland surface water (0.1 ppm) (Kebede and Gashaw 2017). In India, about 2000–3000 tone of chromium discharges into the environment annually from tannery industries (Belay 2010)

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