THE ROLE OF BACTERIA IN WELL CLOGGING

The effect of ochreous sludge from blocked irrigation bores on the oxi dation rate of soluble Fe(II) was studied. Solutions of Fe(II) at an i nitial concentrations of 12-15 ppm were held at 19 degrees C under an oxygen partial pressure of ca 1.4% and the decline in Fe(lI) concentra tion observed. Solutions were buffered with 2-(N-morpholino) ethanesul fonic acid (MES) at pH values of 5.8, 6.0, 6.3 and 6.5. Sterile flasks showed agreement with the expected 1st order behaviour (with respect to [Fe(II)]) while flasks inoculated with ochreous sludge deviated sig nificantly from this pattern. Rates of Fe(II) oxidation were significa ntly enhanced in the inoculated flasks with the greatest increase obse rved at pH 5.8.