Abstract: The invention relates to a sedimentation plant comprising a sedimentation basin (12), a cleaner beam (18) and an ultrasonic sludge level probe (30) which is suspended in the sedimentation basin (12). The cleaner beam (18) collides with the sludge level probe (30) in a regular manner ensuring that the sludge level probe (30) is displaced from the vertical spatial position and that the distance measuring values supplied thereby are no longer required for evaluating the height (h) of the sludge level (40). A positional sensor (34) is associated with the ultrasonic measuring head (32), which determines the spatial position of the ultrasonic measuring head (32). As a result, an error position of the ultrasonic measuring head (32) can be determined and the distance measuring values supplied by the ultrasonic measuring head (32) when in the error position are suppressed when the height (h) of the sludge level (40) is determined.

Abstract: Gas-selective electrodes in liquid analyzing devices have a characteristic K with a linear portion L and a non-linear portion NL. In the non-linear portion NL, the characteristic can only be estimated so that these determinations of the concentration are rather inexact. According to the present method, the electrode is rinsed with an acid and the zero point voltage at the electrode is determined during the rinsing. Using the zero point voltage UN thus quickly obtained, the non-linear portion NL of the characteristic K can be determined with high precision so that even low concentrations c can be determined with great accuracy.