Reduction of nitrate and nitrite in a cyclically operated continuous biological reactor

Abstract

Biological reduction of nitrate and nitrite was studied with a continuously operated cyclic reactor. The medium was fed to the reactor during the first phase of the cycle, and the effluent was drawn from the reactor during the third phase of the cycle; reaction occurred throughout the cycle. The process was described mathematically based on kinetic expressions revealed in an independent study. The model equations were subjected to detailed analysis with numerical codes based on the bifurcation theory for forced systems. The analysis has shown that in the operating parameter space there are extensive regions where the system can reach up to three different periodic states. The results of this analysis are shown in the form of two-dimensional operating diagrams. Numerical results have also shown that under certain operating conditions nitrate can be completely eliminated, while nitrite remains practically untreated. An experimental unit was designed, constructed, and used in experiments with a strain of Pseudomonas denitrificans [American Type Culture Collection (ATCC) 13867] under different operating conditions. The experimental results confirmed the theoretical predictions both qualitatively and quantitatively. Conditions under which complete reduction of both nitrate and nitrite is achieved, were found and experimentally verified. The results of this study suggest a methodology for analysis and design of cyclically operated bioreactors employed in denitrification of wastewaters. (c) 1995 John Wiley & Sons, Inc.

Comparison of Different Carbon Sources for Ground Water Denitrification

“…While in waste water treatment the required carbon source is often present in sufficient amounts, denitrification of ground water requires an addition of a carbon source. Previous research on carbon source-supported denitrification demonstrated successful nitrate removal when using a variety of carbon sources such as acetate [1], glucose [2], ethanol [3][4][5], methanol [6,7], and sawdust [8]. While mechanisms of nitrate removal are similar when using different substrates, the various groups of microorganisms present in the aquifer will differ in substrate affinity, thus denitrification rates and carbon source requirements will be influenced by the choice of substrate.…”

Biodegradation of octylphenol polyethoxylates by denitrification

“…Analyses. NO 2 and NO 3 were quantified by denitrification by capillary electrophoresis (Millipore CIA 4000 in a melt silica column with 75 µm ID and 60 cm long at 30 mA and 20 kV (Wang et al, 1995).…”

Adapting the Self-Cycling Fermentor to Anoxic Conditions

“…The organism used in all experiments was Pseudomonas denitrificans ATCC 13867. The medium used was a modified version of that previously described (11). The base mixture consisted of 1.5 g of KH2-PO4, 5 g of K2HPO4, 5 g of NaCl, 0.06 g of CaCl2, 0.2 MgSO4‚ H2O, 2.207 g of glutamic acid, and 0.05-0.1 mL of a trace elements solution dissolved in 1 L of distilled water.…”