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S. Krner 《洁净——土壤、空气、水》1999,27(1):27-31
A quantification of nitrifying and denitrifying bacteria present in different compartments (water, sediments, submerged macrophytes) of a treated sewage channel was made to estimate their influence on the nitrogen balance and to assess the significance of macrophytes for nitrification and nitrogen conversions in general. Considerable numbers of autotrophic and heterotrophic nitrifying and denitrifiying bacteria were found to be present in the epiphytic communities of different species of submerged macrophytes of a treated sewage channel. Comparing the influence of the different compartments on total stream nitrification and denitrification it could be concluded that dense beds of submerged macrophytes particularly positively influence nitrification. Epiphytic nitrifiers were estimated to be as important for the total nitrification as nitrifiers in the sediment. Denitrification was mainly taking place in the sediment. The influence of the suspended nitrifiers and denitrifiers on the nitrogen balance was assumed to be negligible. 相似文献
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Groundwater denitrification was carried out in a fluidized bed reactor. This type of reactor is suited well to conditions of low substrate concentrations and high flow rates which are typical in groundwater denitrification processes. The reactor is characterized by the efficient contact between biomass and substrate, a high biomass concentration, and the absence of clogging or channeling. These characteristics provide for high treatment capacities (10.8 g/(L·d) NO3?N) and short retention times (less than 3 minutes) resulting in small reactor volume. Start-up procedure, biomass and nitrate profiles, and biofilm characteristics are presented in this article. 相似文献
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Nitrification – Fundamentals of the Metabolism and Problems at the Use of Ammonia Oxidizers From an ecological point of view, a great problem results from the release of increasing amounts of inorganic and organic nitrogen compounds. Apart from gaseous nitrogen compounds, such as the greenhouse gas N2O, soluble nitrogen compounds such as ammonium cause difficulties. In recent years, great progress has been made regarding the reduction of the emission of sulfur and phosphorus compounds. Since there are no effective strategies for the decrease of nitrogen releases, the emission of such compounds has even been increasing. Therefore, great efforts are being made to eliminate the soluble nitrogen compounds in particular, for example in wastewater treatment plants. A decisive meaning befits the chemolithoautotrophic ammonia oxidizers. This review focuses on the ecological consequences of the release of ammonia in particular, the metabolism of the ammonia oxidizing microorganisms under consideration of the latest research results, and the problems that arise in the context of using these bacteria for the removal of ammonia. 相似文献
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A demonstration plant for biological heterotrophic water treatment of nitrate polluted groundwater has been operated in Coswig near Dresden since 1989. In this NEBIO tube reactor process the denitrification is achieved in a downstream fluidized bed with continuous regeneration of sintered polystyrene particles as inert carrier material. A nutrient consisting of ethanol and phosphate is dosed in the reactor influent. In the subsequent treatment stages the denitrified water is aerated, filtered through a multilayer and GAC filter, and is finally disinfected with chlorine gas. The influence of changing raw water quality (oxygen content, pH value) on the process performance was examined. Increasing oxygen concentration lowers the nitrate reduction potential and rises the consumptive ratio ΔC/ΔNO3. The technology shows a high removal performance of 270 g NO3 m?3 h?1 in the range of pH 6.2 to pH 7.3 which is typical for natural groundwaters. The degradation of nitrate is increasingly inhibited for pH values beyond 7.6. Nitrite production occurs significantly in high pH ranges. The results lead to further insight in the stoichiometry of heterotrophic denitrification. By expressing the stoichiometric equations for nitrate and oxygen respiration as functions of oxygen and pH value it could be shown that the influent water quality has strong effects on the consumption of ethanol. A kinetic model was developed to predict the reactor performance under changing raw water conditions. A two stage kinetic model was designed, regarding two main effects: biochemical degradation of oxygen, nitrate and ethanol and distribution of active biomass due to hydraulic properties of the tube reactor. This model may be helpful for reactor design for sites of various ground water qualities. 相似文献
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