Publications (4)8.07 Total impact
Article: Bacteria and fungi in aerosols generated by two different types of wastewater treatment plants.[show abstract] [hide abstract]
ABSTRACT: Raw wastewater is a potential carrier of pathogenic microorganisms and may pose a health risk when pathogenic microorganisms become aerosolized during aeration. Two different types of wastewater treatment plants were investigated, and the amounts of cultivable bacteria and fungi were measured in the emitted aerosols. Average concentrations of 17,000 CFU m(-3) of mesophilic, 2,100 CFU m(-3) of TSA-SB bacteria (bacteria associated with certain waterborne virulence factors), 1700 CFU m(-3) of mesophilic and 45 CFU m(-3) of thermotolerant fungi, were found in the aerosol emitted by the aeration tank of the activated sludge plant. In the aerosol of the fixed-film reactor 3000 CFU m(-3) mesophilic and 730CFUm(-3) TSA-SB bacteria, and 180 CFUm(-3) mesophilic and 14 CFU m(-3) thermotolerant fungi were measured. The specific emissions per population equivalent between the two types of treatment plants differed by two orders of magnitude. The microbial flux based on the open water surface area of the two treatment plants was similar. The aerosolization ratios of cultivable bacteria (expressed as CFU m(-3) aerosol/m(-3) wastewater) ranged between 8.4 x 10(-11) and 4.9 x 10(-9). The aerosolization ratio of fungi was one to three orders of magnitude higher and a significant difference between the two types of treatment plants could be observed.Water Research 10/2002; 36(16):3965-70. · 4.86 Impact Factor
Article: Relationship between release of nitric oxide and CO2 and their dependence on oxidation reduction potential in wastewater treatment.[show abstract] [hide abstract]
ABSTRACT: Nitric oxide (NO) is an intermediate of denitrification process and can be produced by denitrifiers, nitrifiers and other bacteria. In our experiments we measured the dynamic flow of NO depending on oxidation reduction potential (ORP). Different ORP-ranges were related to various carbon loading stages in the wastewater treatment pilot plant. Nitrification and denitrification were achieved by a sequence of aeration and non-aeration periods. Our measurements show that different carbon loading conditions (low feed, balanced and overloaded conditions) did not change the range of the mixing ratio of NO emissions when the aeration conditions like air-flow and temperature were kept constant. Minimum and maximum NO mixing ratios were 34.7 and 91.8 ppbv; 52.3 and 91.3 ppbv; 57.6 and 109 ppbv for low feed, balanced and overloaded conditions, respectively. The curve of the NO graph relied on nitrification/denitrification dynamics. The dependence of NO release on different ORP and CO2-release during the various conditions are shown. Longer aeration times resulted in an increased release of gaseous NO. The net-release of NO g(-1) nitrogen removed was between 0.014% and 0.028%. The NO fluxes to the air were observed between 8.3 and 14.9 mg m(-2) d(-1) NO. The major release occurred during high aeration periods whereas the concentration of dissolved [NOaq] in the wastewater was less than 0.05% of the gaseous release due to very low solubility of the NO.Chemosphere 09/2001; 44(5):1213-21. · 3.21 Impact Factor
Article: The contribution of bacteria and fungal spores to the organic carbon content of cloud water, precipitation and aerosols[show abstract] [hide abstract]
ABSTRACT: To estimate the contribution of bacterial and fungal carbon to the carbon content of atmospheric samples, the number concentrations of bacteria and fungal spores in cloud water, snow, rain and aerosol samples collected at a continental background site in the Austrian Alps were determined. Based on these number concentrations, bacterial and fungal carbon was calculated and related to the total carbon (TC) and organic carbon (OC) contents of the samples. In cloud water samples, an average of 4.5×103 spores ml−1 was found, which corresponds to 1.5% of OC. The average bacterial abundance was 2.0×104 cells ml−1 corresponding to 0.01% of OC. In snow samples, the average concentrations of bacteria and fungi were 3.1×103 cells ml−1 corresponding to 0.015% of TC and 6.2×102 spores ml−1 corresponding to 1.8% of TC, respectively. In aerosol samples, average concentration of bacteria amounted to 1.2×104 cells m−3, which corresponds to 0.03% of OC, while fungal concentrations averaged to 7.3×102 spores m−3 or 0.9% of OC. As fungal spores occur predominantly in the size range >2.1 μm aerodynamic equivalent diameter (a.e.d.), their contribution to the coarse size fraction (2.1–10 μm) was investigated and amounted up to 9.9% of OC.Atmospheric Research.
Article: Approach for a novel control strategy for simultaneous nitrification/denitrification in activated sludge reactors[show abstract] [hide abstract]
ABSTRACT: Biological nitrogen removal in activated sludge processes is conventionally obtained by a sequence of aerobic and anoxic processes. Kinetic mechanisms aecting the oxygen balance could trigger the production of total volatile organic carbon (TVOC) and nitric oxides (NO) under anoxic and anaerobic conditions. Measurements at a wastewater treatment pilot plant of capacity 1.6 m 3 wastewater show that the amount of TVOC and NO produced during the treatment process depends on carbon loading (low feed, balanced and overloaded) and aeration conditions. To con®rm the results ORP, pH and dissolved oxygen (DO) are measured on-line and chemical parameters such as nitrate (NO 3 -N), ammonium (NH 4 -N) and TOC are measured in the wastewater. The ORP observed is in the range of À60 and +198 mV includes optimal setpoints for simultaneous nitri®cation and denitri®cation. From the pattern of NO emission plot, it can be assumed that a part of the produced NO 3 -N is denitri®ed during the aeration period. NO emissions are especially high during denitri®cation conditions at low oxygen rates. The results suggest that both NO and TVOC emission concentrations in combination with ORP can be valuable parameters to control operation of a wastewater treatment plant. Continuous measurements of ORP and NO concentrations for estimation of NO emissions gauging the extent of nitri®cation or denitri®cation in the plant becomes possible.