The gas-permeable membrane process can recover ammonia from manure, reducing pollution whilst converting ammonia into an ammonium salt fertilizer. The process involves manure pH control to increase ammonium (NH4(+)) recovery rate that is normally carried out using an alkali. In this study a new strategy to avoid the use of alkali was tested applying low-rate aeration and nitrification inhibitio...

Ammonia is a major environmental factor influencing biomethanation in full-scale anaerobic digesters. In this study, the effect of different ammonia levels on methanogenic pathways and methanogenic community composition of full-scale biogas plants was investigated. Eight full-scale digesters operating under different ammonia levels were sampled, and the residual biogas production was followed i...

We describe a new kinetic assay for determining urea in serum or urine with use of urease (EC 3.5.1.5) and leucine dehydrogenase (EC 1.4.1.9). The latter enzyme is suitable for the kinetic assay of NH4+ because its Km value for NH4+ at pH 8.75 is large (approximately 500 mmol/L). Interference from endogenous NH4+ in serum or urine is obviated by subtraction of the assayed endogenous NH4+ value ...

The G2, G3, CBS-QB3, and CBS-APNO model chemistry methods and the B3LYP, B3P86, mPW1PW, and PBE1PBE density functional theory (DFT) methods have been used to calculate deltaH(o) and deltaG(o) values for ionic clusters of the ammonium ion complexed with water and ammonia. Results for the clusters NH4(+) (NH3)n and NH4(+) (H2O)n, where n = 1-4, are reported in this paper and compared against expe...

Using new data for the concentrations and δN of the main nitrogen species of NO3 , NH4 , PON (particulate organic nitrogen) and N2 in the Black Sea, we studied the distributions of concentrations and δ N using a coupled physical–biogeochemical model including known biogeochemical processes and nitrogen isotopic fractionation. In the deep anoxic water N2 is supersaturated. This supersaturation r...

Organic products generated from waste activated sludge hydrolysis and fermentation process could be used as supplementary carbon source for enhanced biological nutrient removal. However, accompanied with organics production, large amount of ammonia nitrogen (NH4+-N) and soluble orthophosphorus (SOP) released, which would be negative to the reutilization of sludge carbon source. In this study, b...

Plant and microbial use of nitrogen (N) can be simultaneously mutualistic and competitive, particularly in ecosystems dominated by mycorrhizal fungi. Our goal was to quantify plant uptake of organic and inorganic N across a broad latitudinal gradient of forest ecosystems that varied with respect to overstory taxon, edaphic characteristics, and dominant mycorrhizal association. Using C and N, we...

Drainage ditches are a key conduit of nitrogen (N) from agricultural fields to surface water. The effect of ditch dredging, a common practice to improve drainage, on the fate of N in ditch effluent is not well understood. This study evaluated the effect of dredging on N transport in drainage ditches of the Delmarva Peninsula. Sediments from two ditches draining a single field were collected (0-...