Combined filter for ammonia removal - Part I: Minimal zeolite contact timeand requirements for desorption

The minimal contact time in removal of ammonia ions by ion-exchange with ze olite, Na-form, is determined using the method of differential element. The relationship between the contact time, the water velocity, the effect of r emoval and the initial ammonia concentration is investigated. The obtained data serve as a basis for mathematical modeling of the ion exchange kinetic s and give valuable information about some design parameters of ion-exchang e facilities. Some basic analyses, concerning the desorption of ammonia fro m zeolite, induced mainly from the cations naturally present in surface wat ers ate made. The influence of water velocity and water hardness on such de sorption is investigated, These experimental data and analyses are an essen tial part of a study, the purpose of which is to investigate the possibilit ies for ammonia removal and biological regeneration of zeolite in a combine d facility, using the processes: ion-exchange, desorption induced by small concentrations of cations and biological nitrification. (C) 1999 Published by Elsevier Science Ltd on behalf of the IAWQ. All rights reserved.