BIOFILM FORMATION ON SURFACES OF GLASS AND TEFLON EXPOSED TO TREATED WATER

Biofilm formation on glass and Teflon cylinders, situated on top of ea ch other in vertical glass columns exposed to different types of treat ed water at a Row rate of 0.2 m/s, was determined using ATP analysis a nd heterotrophic plate counts. Biofilm formation rates (BFR) of these water types, as calculated from the linear relationship between exposu re time and biomass accumulated on the cylinder (glass) surface, were 11.1+/-0.7 pg ATP/cm(2) . d (r=0.96) for treated ground water (TGW), 3 8.2+/-4.7 pg ATP/cm(2) . d (r=0.90) for treated river water (TRW) and 382+/-30 pg ATP/cm(2) . d (r=0.94) for TGW supplemented with 100 mu g of acetate-C/l, respectively. Maximum levels of accumulated biomass we re 1300 pg ATP/cm(2) after 114 d of exposure for TGW, 3200 pg ATP/cm(2 ) after 78 d of exposure for TRW and 26,000 pg ATP/cm(2) after 65 d of exposure for TGW with acetate, respectively. Material and position of the cylinder in the columns either had no significant or a small effe ct on biofilm formation, depending on the water type. The effect of ac etate addition on the BFR of TGW clearly demonstrated that biofilm for mation was energy-source limited in this water type. These observation s show that the experimental setup is suited for assessing BFRs of tre ated water.