Anaerobic ammonium oxidation (anammox) is a recently discovered microbial pathway and a cost-effective way to remove ammonium from wastewater. Anammox bacteria have been described as obligate chemolithoautotrophs. However, many chemolithoautotrophs (i.e., nitrifiers) can use organic compounds as a supplementary carbon source. In this study, the effect of organic compounds on anammox bacteria was investigated. It was shown that alcohols inhibited anammox bacteria, while organic acids were converted by them. Methanol was the most potent inhibitor, leading to complete and irreversible loss of activity at concentrations as low as 0.5 mM. Of the organic acids acetate and propionate, propionate was consumed at a higher rate (0.8 nmol min ؊1 mg of protein ؊1 ) by Percoll-purified anammox cells. Glucose, formate, and alanine had no effect on the anammox process. It was shown that propionate was oxidized mainly to CO 2 , with nitrate and/or nitrite as the electron acceptor. The anammox bacteria carried out propionate oxidation simultaneously with anaerobic ammonium oxidation. In an anammox enrichment culture fed with propionate for 150 days, the relative amounts of anammox cells and denitrifiers did not change significantly over time, indicating that anammox bacteria could compete successfully with heterotrophic denitrifiers for propionate. In conclusion, this study shows that anammox bacteria have a more versatile metabolism than previously assumed.Anaerobic ammonium oxidation (anammox) is a recently discovered microbial pathway in the biological nitrogen cycle (9, 27) and a new cost-effective way to remove ammonia from wastewater (3, 6, 15, 16, 21, 22 34, 35). Anammox is carried out by the planctomycetes Candidatus "Brocadia anammoxidans" and Candidatus "Kuenenia stuttgartiensis" and several species of the genus Candidatus "Scalindua" (2,7,8,19,20). Nitrite is the electron acceptor for the anaerobic oxidation of ammonia to dinitrogen gas, and hydrazine is an important intermediate (32). Anammox bacteria have been described as strictly autotrophic, fixing CO 2 with nitrite as the electron donor, leading to the anaerobic production of nitrate (25, 33). The overall nitrogen balance showed a ratio of 1:1.32:0.26 for the conversion of ammonium and nitrite and the production of nitrate (26). The overall anammox reaction is presented in equation 1. Many other chemolithoautotrophs (i.e., nitrifiers) can grow mixotrophically; they can use organic compounds as a supplementory carbon source. This property is advantageous because mixotrophic growth can increase the growth rate and/or yield. In the case of anammox, this is especially advantageous, because both the growth rate (doubling time of 10 to 20 days) and yield (0.066 CO 2 fixed per mol of NH 4 ϩ ) are very low. Previously, it was found that some organic compounds inhibit anammox (32). In this study, the effects of organic compounds on the anammox bacteria and the potential for mixotrophic growth were investigated in detail. In experiments with anammox enrichment cultures an...

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APE1 Asp148Glu and hOGG1 Ser326Cys polymorphisms might be associated with increasing risk of CRC in a Turkish population. Future studies with larger-sized samples, as well as detecting the association of DNA repair genes with other confounding factors will help elucidate the exact roles of DNA repair genes polymorphisms in development and progression of CRC.

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This paper summarizes experimental evaluations on Istanbul domestic wastewaters with respect to their potential of biological nitrogen removal. Characterization studies involve together with relevant carbonaceous and nitrogenous wastewater components, significant rate coefficients affecting aerobic and anoxic processes. Experimental results indicate a low biodegradable carbon to nitrogen ratio and a relatively small readily biodegradable COD fraction. A new method is introduced to determine maximum specific growth rate for autotrophic biomass. Correction factors for biological growth and hydrolysis under anoxic conditions are also assessed. The latter is found to be significantly higher than values proposed in the literature.

For single-sludge denitrification systems, modelling of anoxic reactors currently uses the kinetics of aerobic heterotrophic growth together with a correction factor for anoxic conditions. This coefficient is computed on the basis of respirometric measurements with the assumption that the heterotrophic yield remains the same under aerobic and anoxic coditions. The paper provides the conceptual proof that the yield coefficient is significantly lower for the anoxic growth on the basis of the energetics of the related metabolic processes. This is used for the interpretation of the very high values for the correction factor experimentally determined for a number of industrial wastewaters. A default value for the anoxic heterotrophic yield coefficient is calculated for domestic sewage and compatible wastewaters and proposed for similar evaluations.

BACKGROUND The study rationale was to explore the potential of particle size distribution (PSD) to support COD fractionation of sewage. Accordingly, the main aim focused on establishing the experimental relation between COD fractionation and PSD on two samples of a selected source, one representing the average character of the sewage and the other a weaker sample. PSD analyses were also conducted on effluent samples. RESULTS PSD profiles of COD yielded the typical bimodal distribution, one major peak representing 65% of COD, higher than 1600 nm and the second peak of 10% lower than 2 nm. Results were evaluated to underline the potential of PSD in complementing COD fractionation as related to biodegradation. PSD exhibited a close relationship with COD fractions with different biodegradation characteristics and defined all major COD fractions except the initial soluble and particulate inert COD fractions. CONCLUSION Selection of appropriate values for inert COD fractions together with default kinetic information available for sewage would enable modelling and designing of various biological treatment alternatives without the need for time consuming experiments on COD fractionation. Furthermore, PSD of biological treatment effluent provided concrete evidence for the generation of soluble residual products, which should be part of all modelling evaluations. © 2017 Society of Chemical Industry