Kinetics of denitritification and denitratification in anoxic filters

Abstract

Denitritification and denitratification in anoxic filters were performed to generate experimental data. Also, a kinetic model of denitratification that accounts for intrinsic biokinetics and hydrodynamic behavior of the biofilter is proposed. In denitritification, the simulated results are in good agreement with the experimental data; and a higher nitrite influent concentration gives a higher nitrite reduction efficiency if the denitrifying loading is kept the same. In denitratification, the intermediate nitrite tends to accumulate, and a higher denitrifying loading results in a higher nitrite effluent concentration. By inserting biological and physical parameter values into the kinetic model, the variations in distributed fractions of nitrate‐reductase (f) and nitrite‐reductase (1‐f) with different denitrifying loadings can be estimated by fitting in experimental data. The estimated f increased with an increase in denitrifying loading, implying that a higher denitrifying loading results in a higher nitrite effluent concentration. From parametric sensitivity analyses, the parameter f is more sensitive than other biological and physical parameters. Accordingly, the proposed kinetic model of denitratification can be used to predict the treatment performance of anoxic filters appropriately. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:52–61, 1998.

Model of simultaneous denitrification and methanogenesis in an Upflow Packed‐Bed Biofilm Reactor: Nitrogen compounds' inhibition and pseudo two‐dimensional biofilm model

“…8). The values of the biofilm thickness were very close to those presented by Huang et al ,2 who indicated that the biofilm thickness can be varied between 1244 and 614 µm. The profile of the biofilm thickness throughout the reactor agrees with those found by several authors 24, 30–32.…”

“…These results indicate that the DM process in biofilm tubular reactors is affected principally by mass transfer in the biofilm and not by nitrogen compound inhibition of methanogenesis. The mass transfer in the biofilm has been indicated as a limiting factor by several authors,2, 30, 36 and this depends on hydraulic conditions and biofilm thickness 37. Huang et al 2 indicates that the denitrification process in a biofilter can be considered as having a deep‐biofilm kinetics for biofilm thickness as high as 540 µm, and therefore, the mass transfer resistance in the biofilm should not be neglected.…”

“…Thus, dividing Equation (2.8) by ρ b yields: boundary conditions: There are differences in the maximum growth rates and in the saturation coefficients for nitrate reduction and nitrite reduction, but normally the same bacteria use NO 2 − or NO 3 − . Some researchers have found two fractions of bacterial enzymes responsible for the denitrification system: nitrate‐reductase and nitrite‐reductase enzymes 2. Therefore, two different kinetic expressions were used to define the denitrification kinetics of each step.…”

“…Many industrial processes, such as fertilizer production, explosive manufacturing, refinery processes, and food and organic compound processing, produce significant quantities of nitrogen compounds including nitrate 1. The biological denitrification process is considered a feasible and practical way to remove this compound by first transforming it into NO 2 − − N and then into N 2 , where the second step (NO 2 − − N → N 2 ) is essential in nitrogen removal 1, 2. In the case of heterotrophic denitrification, an external carbon source is required to assure an adequate quantity of electron donors for industrial waste with low organic content 3.…”

Effect of free nitrous acid as inhibitors on nitrate reduction by a biological nutrient removal sludge

“…nitrite reduction to gaseous N 2 ). Furthermore, nitrate and nitrite have been found to inhibit denitrification systems [1,[7][8][9][10][11][12]. Although detailed information is provided in the literature for the inhibition on each individual denitrification step, little attention has been paid to the possible inhibitory effect of sound inhibitor-nitrite with pH considered as a very important factor on denitrification.…”