[Relationship between phosphorus and bacterial regrowth in drinking water]

Limitation of phosphorus on bacterial regrowth was studied in source water, water treatment process and a main distribution pipe of J waterwork in T city, by modified assimilable organic carbon (AOC) method and microbially available phosphorus (MAP) analysis. Based on the study, the result showed that: (1) Concentration of MAP was higher in source water and water treatment process, which was 5-38 microg/L (PO4(3-)-P). However in water distribution system, concentration of MAP was lower, which was less than 5 microg/L (PO4(3-)-P). It changed very little in distribution system. (2) Traditional treatment process can remove MAP efficiently 34.0%-83.7% of MAP can be removed in the process. (3) Generally in source water and water treatment process, there was no evident difference between AOC(potential), AOC(P) and AOC(native). So AOC was the most important factor of bacterial growth. In the main distribution pipe, the concentration of AOC(potential) and AOC(P) were 2-8.7 times of the concentration of AOC(native). So phosphorus limited bacterial regrowth.