Die Einleitung von gereinigtem Abwasser in Seen

Abstract

Discharge o] Treated Wastewater in LakesTreated wastewater discharged into a lake should be introduced below the trophogenic layer. Tracing the marked wastewater by echosounding revealed that the usual discharge method is unsuitable. The wastewater flows more or less to the depth of its own density, which is usually in the trophogenic layer. If there is no movement, that is, current in the water body, the wastewater accumulates at the pipe's mouth. A continuous current is therefore an indispensable prerequisite for a wastewater discharge site. It is only when wastewater is mixed with at least five parts of lake water that it does not rise more than two meters. INHALTSVERZEICHNIS

A practical approach to lake water density from electrical conductivity and temperature

“…The deviation from the reference was lower than 5 % in the range 10 to 27 • C. Among the other compared approaches, TEOS-10 showed the best results, with relative error ranging from −15.7 to 0.1 %. The Bührer and Ambühl (1975) approach resulted in a relative error ranging from −4.0 to 99.3 % and strongly rising with temperatures increasing above 20 • C. Results according to Chen and Millero (1986) ranged between −37.8 and −25.3 %. Lake Geneva.…”

“…To judge the accuracy of our approach, we also inserted results from other formulas in common use for transferring CTD data into density: we included UNESCO (Fofonoff and Millard, 1983), TEOS-10 (IOC et al, 2010), Chen and Millero (1986) and Bührer and Ambühl (1975) (Fig. 1) as far as possible according to the defined range of applicability of the single formula.…”

“…Jellison et al, 1999;Vollmer et al, 2002;Karakas et al, 2003). If the composition is constant and the main constituents are ions, electrical conductivity or salinity may be used as an easy-to-measure proxy for concentrations (Bührer and Ambühl, 1975;Chen and Millero, 1986;Pawlowicz and Feistel, 2012). Imboden and Wüest (1995) discussed the influence of dissolved substances on (potential) density because both the concentration and chemical composition of the total dissolved solids change considerably from lake to lake (see e.g.…”

“…Pawlowicz and Feistel (2012) have considered the application of TEOS-10 (IOC et al, 2010) in several cases different from seawater, correcting the salinity values depending on the composition before applying TEOS-10 (IOC et al, 2010). Bührer and Ambühl (1975) developed an equation to calculate density based on temperature and specific conductance at 20 • C for alpine lakes. In addition, a popular approach was formulated by Chen and Millero (1986) for tuning ocean approaches to freshwater conditions (salinity < 0.6 psu).…”

The main features of seasonal variability in the external forcing and dynamics of a deep mountain lake (Redó, Pyrenees)

“…The annual mean air pressure at the lake (± one standard deviation) was estimated to be 779.5 ±7.0 hPa. Applying the empirical formula of Bührer and Ambühl (1975), this implies an O 2 saturation concentration of 10.1 ±0.1 mg O 2 ·l -1 at 4°C (i.e., during overturn).…”