Oxygen-Nitrogen Relationships in Autotrophic Nitrification

Abstract

Oxygen utilization by the autotrophic nitrifiers Nitrosomonas and Nitrobacter was studied. Experimental evidence is presented which reflects the effect of carbon dioxide fixation on overall oxygen utilization in autotrophic nitrification. Measurement of dissolved oxygen and inorganic nitrogen changes indicates that oxygen-nitrogen ratios in inorganic nitrogen oxidation are equal to 3.22 parts (expressed in milligrams per liter) of oxygen per part of ammonia nitrogen oxidized to nitrite nitrogen and 1.11 parts of oxygen per part of nitrite nitrogen oxidized to nitrate nitrogen. These values rather than the stoichiometric ratios should be used in nitrogenous oxygen demand calculations.

In Vivo Evaluation of Oxygenic Photogranules’ Photosynthetic Capacity by Pulse Amplitude Modulation and Phototrophic–Irradiance Curves

“…Wastewater was added to suppress dissolved oxygen (DO) saturation in the reactor bulk fluid and to prevent gas loss into the headspace. Net POE was determined as the sum of differential changes in DO concentration, gross nitrification, and COD removal. An oxygen consumption rate of 4.57 mgO 2 /mgNH 3 –N for the oxidation of ammonia − and a ratio of 1 mgO 2 /mgCOD was used for biological oxidation of dissolved organics.…”

A low-cost graphitized sand filter to deliver MC-LR-free potable water: Water treatment plants and household perspective

“…Also, ammonia-N removal in FM1 (4.1 ± 0.3 to 1.1 ± 0.1) is comparatively higher than FM2 (4.1 ± 0.3 to 3.3 ± 0.4) and could be due to presence of more nitrifying bacteria attached over the GS1 adsorbent as compared to sand. Nitrification proceeds with a decrease in pH and consumption of oxygen (4.47 mg O2 per 1 mg of ammonia-N) and hence the presence of carbon utilizing bacteria and more active nitrifiers present in GS1 filter might be the reason for pH and DO relationship as discussed (Wezernak and Gannon, 1967). However, a long-term evaluation and genomic analysis of the formed biofilm could lead to a more definite conclusion on the relative abundance and identification of high carbon utilizing bacterial species.…”

Estimation of nitrifying and heterotrophic bacterial activity in biofilm formed on RAS biofilter carriers by respirometry

“…The deviation between the predicted and observed values for biofilter performance for PF carriers may be the result of different factors, such as that i) respirometric tests and nitrification batch kinetic tests were performed separately, ii) differences in hydraulic conditions in reactors (closed respirometric chamber vs. open beaker) might have an influence on oxygen and substrate diffusion, iii) a part of ammonia, as well as small amount of electrons from TAN oxidation and nitrite oxidation processes are used for cell synthesis, which has a lower oxygen demand than predicted by the theoretical oxygen demand (ThOD) (Liu and Wang, 2012). Furthermore, the oxygen consumed in the endogenous decay of nitrifiers was not considered in stoichiometric relationships, resulting in a slight overestimation of the ThOD for nitrification (Wezernak and Gannon, 1967). Hence, an empirical value of 4.18 g O 2 for 1 g of TAN converted to non-toxic nitrate for autotrophic nitrification process has been recommended when designing biofilters in RAS (Eq.…”