1999 Volume 22 Issue 7 Pages 574-580
Characteristics of soluble organic compounds which were accumulated in the activated sludge process with ultrafiltration for solid-liquid separation were evaluated through bench-scale experiments of artificial wastewater treatment. In one experiment (Run I), a sheet of ultrafiltration membrane was used during the whole experiment. However, in the other experiment (Run II), frequent replacement of ultrafiltration membrane was performed to control the accumulation of the compounds in the second stage of the experiment after around one month.
In the both cases with and without replacement of the membrane, TOC concentration and E260 value of the filtrate increased to each maximum value. However, in Run II with frequent replacement of the membrane, TOC concentration and E260 value decreased, and oxygen uptake rate for substarate metabolism was recovered to a certain level.
In Run I without replacement of the membrane, effects of the organic compounds on the growth of E. coli was examined to evaluate the potential effects of membrane separation on the growth of enteric bacteria. Those compounds had the actions to shorten a lag time and to suppress maximum biomass. As for the actions to maximum growth rate, there were two groups of compounds which accelerate and suppress. And the membrane blocked the compounds to suppress maximum growth rate and maximum biomass, but a portion of the compounds to shorten lag time passed through the membrane.
