MONITORING OF MICROBIAL PHOSPHORUS RELEASE IN BATCH EXPERIMENTS USINGELECTRIC-CONDUCTIVITY

The ionic conductivity of an enhanced biological phosphorus removing ( EBPR) sludge shows a clear behavior during the non-aerated phase. It d ecreases during denitrification and increases under anaerobic conditio ns proportionally to the phosphate concentration. The absolute value o f this increase related to the release of phosphorus was determined be tween 1.66 x 10(-4) to 1.99 x 10(-4) S m(2)g(p)(-1) (at 293 K and an i onic strength of about 650 x 10(-4) S m(-1)). Theoretical calculations are in good agreement with these results. Potassium, magnesium, calci um and phosphate show a positive, whereas acetate and pH show a negati ve correlation to the ionic conductivity. This method is an easy and i nexpensive in-line method providing more information about phosphorus release. Under some circumstances (low salinity, sequencing batch reac tor) it may be used to estimate the anaerobic increase of phosphorus c oncentration.