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The paper presents research on hemoglobin (Hb)-expressing bacteria in biological wastewater treatment systems. The outcome(s) will greatly reduce the aeration needs of wastewater treatment plants (WWTPs) and provide insight into emerging biological nitrogen removal processes using low dissolved oxygen (DO) conditions. In anthropogenic terms, the bacteria that express Hb could be considered as 'bacterial sherpas' that can function under low DO conditions. Hitherto, this functionality of bacteria has not been realized due to the initial response of the aerobic treatment stage: namely, morphology change by bacteria to filamentous forms to overcome oxygen mass transfer limitations causing bulking/foaming and nitrification inhibition. There is evidence, however, of the potential expression of Hb proteins by activated sludge (AS) bacteria. First, bacteria known to possess genes coding Hb proteins have been isolated from AS systems. Secondly, there is evidence that WWTPs are able to operate their biological processes at low DO without sludge bulking or incomplete nitrification. Our research has focused on nitrifying systems and has shown that this is due to prolonged operation at low DO conditions (0.1 mg O2/L), which allows sufficient time for bacterial acclimation. Additionally, it has been shown that enhanced Hb expression is linked to acclimation to low DO conditions.

Owing to less natural snow reliability as a result of climate change on the one hand, and the demand of higher standards by winter tourists on the other hand, the production of artificial snow in ski resorts has increased substantially during the last 20 years and is likely to increase further in future. Little research has been conducted on the impact of snowmaking as a water demand stakeholder on a regional water balance. In this paper, a regional water balance (water demand-water resources) is analysed for the greater Kitzbueheler Region in the Austrian Alps, for the current situation and a future climate change scenario (28C warming). For this temperature rise a significant reduction in natural snow cover duration and snow accumulation is predicted, an effect that increases with lower altitudes and differs between the winter months. Due to the shortening of the winter season, a change in seasonality of river flows and available water resources (ground and surface water) occurs. Both increase in winter, and decrease in spring. The water demand for improvement snowmaking increases, especially in the month of March. However, December proved to be the critical month due to the large amounts of water required for base snowmaking both now and in future. These results stress the necessity of reservoir storage for base snowmaking on a regional level. Water availability during other months but winter is sufficient to fill these reservoirs. [ABSTRACT FROM AUTHOR]

The variation of concentration of the toxic substrate has a negative effect on the sludge activity. Although this loss of activity of the microorganisms under toxic starvation has been reported, this variable is not taken into account in the operation of biological wastewater treatment plants. In order to monitor and control the biological plant with a certain confidence it is necessary to consider the acclimation and deacclimation processes to avoid the reactor malfunctioning, resulting in loss of efficiency or in false data acquisition during monitoring. This paper proposes a model for the acclimation/deacclimation process. The experiments have been done in a sequencing batch reactor during the 4-chlorophenol degradation. The basic idea of the model is to consider the variation of the kinetic parameters of the Haldane law in terms of the acclimation and deacclimation state. The idea is discussed, and the results obtained are presented. [ABSTRACT FROM AUTHOR]