Abstract
The characteristics of organic compounds accumulated in bioreactors were examined by using experimental benchscale plants of the activated sludge processs with dead end or cross flow ultrafiltration system.
Use of ultrafiltration system brought easily highly concentrated activated sludge suspension in the bioreactors, compared with use of sedimentation system. At the sam time, organic compounds with wide range of molecular weight were accumulated in the bioreactors by introducing ultrafiltration system.
Accumulated organic compounds were fractionalized by the gel permeation chromatography using high performance liquid clromatograph(HPLC). A large molecular weight group was composed of organic compounds with a relatively low ratio of E260/TOC, and accumulated predominantly according to treatment performance. A medium molecular weight group was composed of organic compounds with a large ratio of E260/TOC, and molecular weight of the peak was estimated to he about 1,300 on the basis of polyethyleneglycol. A small molecular weight group was also composed of organic compounds with a large ratio of E260/TOC, which might be derived from activated sludge destroyed by the feeding pump to the ultrafiltration membrane module. The small and medium molecular weight groups permeable the membrane in nature was accumulated possibly by dynamic membrane developed on the membrane.
Oxygen uptake rate for substrate metabolism of activated sludge decreased largely according to treatment performance in the process with ultrafiltration system. One possible reason for this phenomenon is assumed to be inhibitory effects of the accumulated organic compounds.
