Nitrogen removal from wastewater by a catalytic oxidation method

The ammonia-containing waste produced in industries is usually characterize d by high concentration and high temperature, and is not treatable by biolo gical methods directly. In this study, a hydrophobic Pt/SDB catalyst was fi rst used in a trickle-bed reactor to remove ammonia from wastewater. In the reactor, both stripping and catalytic oxidation occur simultaneously. It w as found that higher temperature and higher oxygen partial pressure enhance d the ammonia removal. A reaction pathway, which involves oxidizing ammonia to nitric oxide, which then further reacts with ammonia to produce nitroge n and water, was confirmed. Small amounts of by-products, nitrites and nitr ates were also detected in the resultant reaction solution. These compounds came from the absorption of nitrogen oxides. Both the minimum NO2- selecti vity and maximum ammonia removal were achieved when the resultant pH of tre ated water was near 7.5 for a feed of unbuffered ammonia solution. (C) 2001 Elsevier Science Ltd. All rights reserved.