[Oxidization characteristic of chlorine on the biofilm in simulated drinking water distribution system]

In the article, the inactivation effect of chlorine on E. coli biofilm and the influence of chlorine oxidization on the contents of assimilable organic carbon (AOC), microbially available phosphorus (MAP) and bacterial regrowth potential (BRP) was investigated in the simulated drinking water distribution system. Results showed that chlorine resulted in more efficient reduction on suspended E. coli than did in biofilm. The inactivation effect of E. coli was influenced by chlorine concentration. Likewise, higher chlorine concentration resulted in more E. coli inactivation rate at the same CT (chlorine concentration multiply by time) value, when biofilm was oxidized by chlorine. Concentrations of AOC and MAP in bulk water increased owing to organic substance dissolved from biofilm. The AOC concentration increased from 20.78 microg/L to 120.17 microg/L, and the MAP was increased from 0.11 microg/L to 0.17 pg/L, and the Chlorine oxidization enhanced BRP concentration in the bulk water. BRP reached maximum at 1.10 x 10(7) CFU/mL when chlorine concentration was 1.0 mg/L, CT value was 100 mg x min/L.