1. Abdel-raouf M, Abdul-raheim A (2017) Removal of heavy metals from industrial waste water by biomass-based materials: a review. J Pollut Effects Control 5(1):1–13
2. Adane T, Haile D, Dessie A, Abebe Y, Dagne H (2020) Response surface methodology as a statistical tool for optimization of removal of chromium (VI) from aqueous solution by Teff (Eragrostis teff) husk activated carbon. Appl Water Sci 10(1):1–13
3. Alfa-sika MS-L, Liu F, Chen H (2010) Optimization of key parameters for chromium (VI) removal from aqueous solutions using activated charcoal. J Soil Sci Environ Manag 1(3):55–62
4. Amabye TG (2015) Plant, soil and water pollution due to tannery effluent a case study from Sheb Tannery PLC, Wukro Tigray, Ethiopia. Science 3(5):47–51
5. Apha (2005) Standard methods for the examination of water and wastewater. American Public Health Association (APHA), Washington, DC