Category: Water, Wastewater & Storm water
Tannery wastewater is usually highly colored due to use of basic chromium salt, different syntans, dyes, pigments, retanning agents etc. in the tanning process and successful removal of color is not always possible after primary and secondary treatment. Since advanced tertiary treatment is expensive, there is a general interest in looking for less-expensive methods and using locally available materials for removing color from wastewater. We used Powdered Activated Carbon (PAC) generated from rice husk, an abundant agricultural waste in Bangladesh, as an adsorbent for the removal of color from tannery wastewater. Batch adsorption experiments were performed over a range of contact periods and wastewater pollutant (color) levels. A maximum absorbance reduction of 94.13% was observed when methylene blue is used as a proxy for colored dyes while experiments with tannery wastewater yielded a 77% reduction in color. Both Langmuir and Freundlich isotherm models represented the adsorption process relatively well with the Langmuir model having a slightly better fit (R2 = 0.98) than the Freundlich model (R2 = 0.93). The Langergen pseudo second-order kinetic model fitted better (R2 = 0.99) for initial color concentrations of 300 and 400 Pt-Co while the first-order model fitted better when initial color concentration was 500 Pt-Co indicating that chemisorption may be playing a dominant role in the adsorption process for high color concentrations. These experiments suggests that rice husk PAC is an effective adsorbent, capable of removing a reasonable amount of color from industrial wastewater if process variables can be optimized and can be used as a cheaper alternative to expensive tertiary treatment options.
Bangladesh University of Engineering & Technology
Dr. Tanvir Ahmed received his Bachelors and Masters degree in Civil Engineering from BUET in 2003 and 2005, respectively and PhD from Massachusetts Institute of Technology (MIT), USA in 2011. He has been a faculty of BUET since 2003 and currently working as an Associate Professor in the Department of Civil Engineering. His research interest broadly encompasses environmental modeling and health risk assessment of environmental contaminants and authored several papers in distinguished journals and conferences. He is involved in several national and international projects as a consultant and EIA specialist. Since 2015, he is working as an environmental specialist for the World Bank providing environmental safeguard support to various Bank-funded projects in Bangladesh.
Dr. Ahmed received a number of awards in recognition for his excellence in academic achievements and teaching. These include The Prime Minister’s Gold Medal in 1994 for securing the 1stmerit position in the national SSC exam, Malik Akram Hossain Gold Medal in 2003 and Dean’s award for academic excellence as a civil engineering student. He received the Schoettler Fellowship and Martin Fellowship for Sustainability while pursuing his PhD at MIT and was awarded the Maseeh Award for excellence in teaching from MIT in 2009. He is the author of the textbook “Environmental Sanitation, Wastewater Treatment and Disposal” published by the University Grants Commission.