Simulations of Arctic denitrification using a 3D chemistry-microphysics transport model are compared with observations for the winters 1994/95, 1996/97 and 1999/2000. The model of Denitrification by Lagrangian Particle Sedimentation (DLAPSE) couples the full chemical scheme of the 3-D chemical transport model, SLIMCAT, with a nitric acid trihydrate (NAT) growth and sedimentation scheme. We use ...

Simultaneous nitrification and denitrification (SND) under low dissolved oxygen (DO) and anaerobic/aerobic(anoxic) enhanced phosphorus removal (EBPR) are two processes that can significantly reduce the energy and carbon required for nutrient removal. The combination of the two processes is expected to achieve biological nutrient removal with minimal requirement of oxygen and carbon. In this stu...

In this research, an experimental study to evaluate nutrient removal from synthetic wastewater by a lab-scale moving bed biofilm process was investigated. Also, kinetic analysis of the process with regard to phosphorus and nitrogen removal was studied with different mathematical models. For nutrient removal, the moving bed biofilm process was applied in series with anaerobic, anoxic and aerobic...

Denitrification and nitrification in sediments of Tama Estuary and Odawa Bay, Japan, were investigated by the combined use of a continuous-flow sediment-water system and a N tracer technique. At Odawa Bay, the nitrification rate was comparable to the nitrate reduction rate, and 70% of the N(2) evolved originated from nitrogenous oxides (nitrate and nitrite) which were produced by the action of ...

This paper presents a biological method for controlling odor problems caused by H2S originating from sewer networks under anaerobic conditions. The proposed method is based on the continuous addition of nitrate which oxidizes dissolved sulphide according to an autotrophic biological procedure and inhibits further sulphide production by sulphate reducing bacteria, until complete denitrification....

globally, increasing nitrate concentrations have become a significant environmental problem and a potential risk to public health. the world health organization (who) has set a limit of (10 (mg.l -1 )) no 3 - for human consumption and (100 mg.l -1 )) no 3 - for animals. water above these limits requires denitrification. nitrates causes cancer, blue-bay syndrome, hypertension and thyroid hypertr...

Denitrification of the Arctic winter stratosphere has been calculated using a 3-D micro-tion is assumed to occur through the sedimentation of low number concentrations of large nitric acid trihydrate (NAT) particles, as observed extensively in 1999/2000. We 5 examine whether the meteorological conditions that allowed NAT particles to grow to the very large sizes observed in 1999/2000 also occur...

A major impediment to understanding long-term changes in the marine nitrogen (N) cycle is the persistent uncertainty about the rates, distribution, and sensitivity of its largest fluxes in the modern ocean. We use a global ocean circulation model to obtain the first 3-D estimate of marine denitrification rates that is maximally consistent with available observations of nitrate deficits and the ...

Direct measurements of dinitrogen efflux from continental shelf sediments ~ndicated that denltnflcation (mean 3.2 mm01 N m-2 d-l) was very important ~n nitrogen cycling. Most dinitrogen came from sediment-nitrate. All ammonium produced in these sediments was probably nitrified and then denitrified. In a closed incubation, the linear production of dinitrogen, a s oxygen decreased, was unexpected...

The influence of burrow spacing on sedimentary nitrification and denitrification was simulated experimentally using sediment plugs of different thicknesses immersed in aerated seawater reservoirs. Different plug thicknesses mimic different distances between oxygenated burrow centers and produce similar changes in aerobic–anaerobic reaction balances as a function of diffusive transport scaling. ...