MODELING AND SIMULATION OF ION-EXCHANGE PROCESS FOR REMOVAL OF AMMONIUM FROM TREATED WASTEWATER USING ZEOLITE

Abstract

Ammonium removal by ion exchange using natural zeolite has gained much attention within last 20 years. It has various advantages over the conventional biological nitrification-denitrification and air stripping techniques. Ion exchange is stable process, suits automation and quality control, and is easy to maintain. Land requirement with the ion-exchange process is relatively low, making the process, generally a much cheaper option. The ion exchange kinetics shows a complex behavior. The possible rate controlling mechanisms could be film-diffusion control, particle-diffusion control, and chemical reaction control. When ion exchange is considered for use as an ammonium removal process extensive studies for the process kinetics, evaluation of the variables such as loading rate, contact time, etc. are required. This thesis work is an effort to determine the reaction kinetics of the ion exchange process using clinoptilolite, a naturally occurring zeolite used for removal of ammonium from waste water and then to extend these results to pilot plant studies for forming a simple model. Evaluation of process is undertaken for ammonium removal ammonium chloride solution. Equilibrium relationship for ammonium distribution has been determined in batch systems. Freundlich Isotherm is found to be more appropriate for the system giving the equilibrium relation as Q = 1.3477C, 0.3867 . Experiments showed that the process is very rapid and a contact time of 60 min is sufficient for quantitative removal of ammoniacal nitrogen. Also, by increasing the initial concentration of ammoniacal nitrogen, the removal efficiency quickly decreases.