Table 1.

Incubation conditions used for experimentsa

ExptSampleConcn of suspend-ed solids (g/liter)Nonradioactive substrate(s)Radioactive tracerIncubation conditionsIncubation time (h)
CompoundConcn (μCi/mg of suspended solids)
1Pure cultures of E. coli and H. aurantiacus 1Glucose (1 mM)b d-[6-3H]glucose20Aerobic3–24
2Activated sludge (Kraftisried)1Ammonia (3 mM)Sodium [14]bicarbonate20Aerobic8
3Activated sludge (Kraftisried)1Ammonia (3 mM)Sodium [14C]bicarbonate20Aerobic8
4Activated sludge (Malmö)c 2Monobasic phosphate (0.3 mM) + sodium acetate (1 mM) 33Pi 10Anaerobic2
5Activated sludge (Kraftisried)1Ammonia (3 mM) + sodium acetate (1 mM)Sodium [2-14C]acetate10Aerobic2
6Activated sludge (Kraftisried)1Ammonia (3 mM) + sodium acetate (1 mM) + potassium nitrate (2 mM)Sodium [2-14C]acetate10Anaerobic with nitrate2
7Activated sludge (Kraftisried)1Ammonia (3 mM) + sodium acetate (1 mM)Sodium [2-14C]acetate10Anaerobic2
8Activated sludge (Kraftisried)1Ammonia (3 mM) + sodium butyrate (1 mM)Sodium [2-14C]butyrate10Aerobic2
9Activated sludge (Kraftisried)1Ammonia (3 mM) + sodium butyrate (1 mM) + potassium nitrate (2 mM)Sodium [2-14C]butyrate10Anaerobic with nitrate2
10Activated sludge (Kraftisried)1Ammonia (3 mM) + sodium butyrate (1 mM)Sodium [2-14C]butyrate10Anaerobic2
  • a All experiments were performed at room temperature at pH 7 to 7.5 when substrates were added.

  • b The concentrations in parentheses are the absolute amounts added.

  • c Two parallel incubations were performed in order to differentiate between chemically and biologically induced P removal by using different washing procedures (see Materials and Methods).