Ammonia

About: Ammonia is a research topic. Over the lifetime, 16217 publications have been published within this topic receiving 271940 citations. The topic is also known as: NH3 & azane.

Growth inhibition by ammonia and use of a pH-controlled feeding strategy for the effective cultivation of Mycobacterium chlorophenolicum.

Abstract: The inhibitory effect of ammonia on the growth of the polychlorinated xenobiotic-degrading bacterium Mycobacterium chlorophenolicum was examined. The strain is inhibited by both the ionized and nonionized forms of ammonia. At pH 6.9 50% reduction of the growth rate was observed at 6.8 g l−1 total ammonium. For 23 experiments performed in shake-flask culture at different pH values and ammonium concentrations a growth model based on the extended Monod kinetic fits the data with a deviation of 5.3%. To overcome growth inhibition in bioreactors a pH-controlled feeding strategy was developed for effective cultivation of M. chlorophenolicum at an ammonium level below 0.3 g l−1. The ammonium addition was controlled on-line by the stoichiometric interdependence of ammonium consumption and pH decline. With this on-line control strategy a biomass concentration as high as 26.2 g l−1 can be achieved within less than 1 week of cultivation, compared to a biomass concentration of 15.5 g l−1 in normal batch culture after 2 weeks of cultivation. The yield is also increased from 0.32 g to 0.43 g biomass (g glucose)−1. The strategy developed provides an effective method for the production of biomass of M. chlorophenolicum serving as the inoculum in remediation technologies.

Rate and mode of application of the urease inhibitor N-(n-butyl) thiophosphoric triamide on ammonia volatilization from surface-applied urea

Abstract: A laboratory study evaluated the effect of rate (0, 100, 250, 500, 750 or 1000 mg/kg) and mode of application of the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) (coating the urea granule, adding to the urea melt or adding to urea ammonium nitrate (UAN) solutions) on NH 3 volatilization from urea, at three temperatures (5, 15 and 25 °C), with four contrasting soil types. Daily ammonia loss was measured for up to 21 days after surface N application, using ventilated soil enclosures. Ammonia loss from unamended urea varied with soil type and temperature and ranged from 8.2 to 31.9% of the N applied. nBTPT was highly effective in lowering NH 3 volatilization from urea and in delaying the time of maximum rate of loss. The average % inhibition over all soils, temperatures and formulations was 61.2, 69.9, 74.2, 79.2 and 79.8% for the 100, 250, 500, 750 or 1000 mg/kg nBTPT concentration, respectively. The % inhibition with nBTPT was lower at 15 °C compared with at 5 or 25 °C and was lower in UAN solutions than in granular products. There was little difference between the melted and coated granular products in lowering NH 3 loss or in soil N transformations. The stability of nBTPT in urea products was dependent on its mode of application and on the storage temperature. Incorporating nBTPT in the urea melt produced a more homogeneous product with superior stability than coating the urea granule.