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QUANTITATIVE STUDIES ON THE REACTION OF CHLORINE WITH BACTERIA IN WATER DISINFECTION
Author(s) -
Friberg Lars
Publication year - 1956
Publication title -
acta pathologica microbiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0365-5555
DOI - 10.1111/j.1699-0463.1956.tb00987.x
Subject(s) - chlorine , bacteria , chemistry , chloride , environmental chemistry , organic chemistry , biology , genetics
SUMMARY The reaction of chlorine with bacteria in water disinfection was under various conditions investigated by studying how large a portion of the free available chlorine used‐up was taken up by the bacteria. The amount of the free available chlorine used in the experiments was such that after a 5‐minute exposure none was present any more, i.e. neither free nor combined available chlorine. Great care was exercised in reducing organic impurities to a minimum. All experiments were performed with radioactive chlorine (Cl 36 ). The bacteria used were Esch. coli and Staph. aureus in concentrations of about 50 × 10 6 bacteria per ml water. The period of exposure of the bacteria to chlorine was 5 minutes. The experiments were carried out at a water temperature of about 20° C and pH‐rates of 6.5 and 8.2 respectively. In connexion with the investigations certain studies were performed as to a possible isotopic exchange reaction between free available chlorine and chloride ions. Results (1) On an average, from 10 per cent to 25 per cent of the free available chlorine used‐up was found in the bacteria after a 5‐minute exposure to 0.5 ppm free available chlorine. (After this period no chlorine was present as free available or combined available chlorine.) (2) An influence was noted of the pH‐rate, i.e. at pH 6.5 the corresponding value was 10–11 per cent, but at pH 8.2 it was 22–25 per cent. (3) On the other hand, no significant difference as regards the amount of absorbed chlorine was demonstrated between Esch. coli and Staph. aureus. (4) The more free available chlorine was added, the larger was the amount of the used‐up chlorine residual demonstrated in the bacteria. Thus, with addition of 0.25, 0.5, and 1.0 ppm respectively of free available chlorine, values of about 5 per cent, 13 per cent, and 27 per cent respectively were obtained. These experiments were carried out with Esch. coli only, and at pH 6.5. (5) No isotopic exchange reaction bearing on the results was demonstrated between free available chlorine and chloride ions.