Determining mean water content in e.g. biofiltration bed, measures differential air pressure using sensors, using result to determine mean water content

The pressure differential across the bed (12) is measured using pressure sensor(s) (17), the value obtained being used to determine mean water content. An Independent claim is included for corresponding equipment. Preferred features: A first relationship is determined between pressure drop and mean water content. In addition, the spatial water distribution in the bed is measured using two or more water content sensors (16). From the results a second relationship is established between water content at reference locations (20) of the bed and the pressure drop through it. Reference locations are fewer in number than the water content sensors. Reference location(s) coincide with water content sensor positions. The gas is air, saturated with water vapor. First and/or second relationships are determined using soft computing methods, especially using fuzzy logic or neural networks, with fuzzy processing algorithms. The first and/or second relationship is converted into an apparatus-independent run-time code. Water content of the medium is controlled through a supply valve in a surface-wetting unit as a function of the mean water content determined. The second functional relationship is used to dived up the operating medium states into groups with respect to water content distribution. Groups identified are at least: too dry, too wet, desired state, locally dry bed, locally excessively-wet bed. Die Erfindung betrifft ein Verfahren zur Bestimmung des durchschnittlichen Wassergehaltes eines von einem Fluid durchströmten heterogenen Mediums (12), insbesondere des Filterbettes (12) eines Biofilters (10). Erfindungsgemäß wird der Wassergehalt bestimmt, indem neben einem Wassergehaltssensor an einer Referenzstelle zusätzlich der Druckabfall über das Medium (12) mit mindestens einem Drucksensor (17) gemessen und der Druckabfall zur genaueren Bestimmung des durchschnittlichen Wassergehaltes des Mediums (12) und zur Einteilung in Betriebsmerkmalsgruppen (zu hoch, Fehler, Sollzustand, zu feucht) verwendet wird. Dadurch ist eine kostengünstige Bestimmung des durchschnittlichen Wassergehaltes möglich.