IOSR Journal Of Environmental Science, Toxicology And Food Technology (IOSR-JESTFT) e-ISSN: 2319-2402,p- ISSN: 2319-2399.Volume 6, Issue 1 (Sep. - Oct. 2013), PP 01-06 www.Iosrjournals.Org www.iosrjournals.org 1 | Page Studies on Fixed and Fluidized Bed Ion Exchange Column to Treat Wastewater Majid Farajpourlar 1 , S. Ram Mohan Rao 2 , V. V. Basava Rao 3 . 1,2,3. Department of Chemical Engineering, University College of Technology, Osmania University, Hyderabad-07, India Abstract: A continuous fixed and fluidized bed study was carried out by using strong-base anion- exchange resin for removal of nitrate from water. The effect of operating parameters, such as flow rate, initial concentration and bed high was studied. Data confirmed that the breakthrough curves were dependent on flow rate, initial concentration and bed high. Breakthrough experiments were carried out to compare breakthrough curves between packed and fluidized beds. Thomas model was applied to experimental data to predict the breakthrough curves and to determine the characteristic parameters of the packed and fluidized bed columns. Key words:nitrate removal; fixed bed; fluidized bed; ion exchange I. Introduction Increased levels of nitrate in ground water have made many wells unsuitable as sources for drinking water. Nitrate is so toxic, especially to pregnant women and infants, that the USEPA (United States Environmental Protection Agency) standard of 10 mg NO 3 - N/L or less in drinking water were established for human health(i.e.,[1],[2]). The primary health concern regarding nitrate, NO 3 - , is that it is reduced to nitrite, NO 2 - , in the body. Nitrite in turn reactswith the red blood cells to form methemoglobin, which affects the blood’s capability to transportoxygen. High intake of nitrate by infants when bottle-fed, can causes a condition known as “blue-baby” syndrome that can be fatal. It is also claimed by some researchers that there exist a correlationbetween exposure to nitrate and the risk of developing cancer (i.e.,[3]). Several processes have been described for nitrate removal from portable water among which ion exchange and biological denitrification are the only ones considered feasible and practical for full-scale treatment (i.e.,[4]). Nitrate removal from water using ion exchange is economical and convenient and provides a suitable solution for small or medium-sized water treatment plants containing comparably low nitrate level. Ion exchange is the most common process for public water supplies in the United States(i.e.,[1]). Ion exchange is a chemical treatment process used to remove unwanted ionic species from waste water. As the name implies, ion exchange works byexchanging undesirable cations or anions in solution with less harmful ones(i.e.,[4],[5]). II. Modeling of column operation Full-scale column operation can be designed on the basis of data collected in laboratory level. Many mathematical models have been proposed in the past for the evaluation of efficiency and applicability of the column models for large scale operations. To design a column sorption process it was necessary to predict the breakthrough curve or concentration time profile and sorption capacity of the sorbent for the selected sorbate under the given set of operating conditions. Many models have been developed to predict the sorption breakthrough behaviour with high degree of accuracy. The Thomas model was used in this study to analyse the behaviour of the selected adsorbent-adsorbate system. 2.1 Thomas model The Thomas model is one of the most general and widely used. The model is applicable in system with a constant flow rate and no axial dispersion, and its behavior matches the Langmuir isotherm and the second-order reversible reaction kinetics. The model hasthe following form: (i.e.,[6]).   0 = 1 1 + exp[  ℎ   0 . − 0 ] Where km is the rate constant (L/mmol h), q o is sorption capacity of the column (mg/g), Q is flow rate (L/h), m is mass of the bed (g) and V is effluent volume (L). The linearization of above equation: ln   0  − 1 = k Th .q 0 .m Q – k Th .C 0 .t From the linear dependence ofln{(Co/C)-1] versus t, the removal capacity q and rate constant k Th can be